v3.26.1
Shareholder Report
 6 Months Ended
May 31, 2026
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name MASSACHUSETTS INVESTORS GROWTH STOCK FUND
Entity Central Index Key 0000063090
Entity Investment Company Type N-1A
Document Period End Date May 31, 2026
C000112291 [Member]  
Shareholder Report [Line Items]  
Fund Name Massachusetts InvestorsGrowth Stock Fund
Class Name Class R6
Trading Symbol MIGNX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about Massachusetts Investors Growth Stock Fund for the period of December 1, 2025 to May 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R6 $18 0.37%
Expenses Paid, Amount $ 18
Expense Ratio, Percent 0.37%
Net Assets $ 9,167,689,749
Holdings Count | Holding 54
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 5/31/26
Net Assets ($): 9,167,689,749 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 54
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 5/31/26)
Portfolio structure
Equities 99.1%
Money Market Funds 0.9%
Equity sectors
Information Technology 40.1%
Financials 13.1%
Health Care 11.2%
Industrials 10.4%
Consumer Discretionary 9.8%
Communication Services 7.3%
Consumer Staples 4.2%
Utilities 2.0%
Materials 0.9%
Real Estate 0.1%
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
C000002025 [Member]  
Shareholder Report [Line Items]  
Fund Name Massachusetts InvestorsGrowth Stock Fund
Class Name Class R4
Trading Symbol MIGKX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about Massachusetts Investors Growth Stock Fund for the period of December 1, 2025 to May 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R4 $23 0.46%
Expenses Paid, Amount $ 23
Expense Ratio, Percent 0.46%
Net Assets $ 9,167,689,749
Holdings Count | Holding 54
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 5/31/26
Net Assets ($): 9,167,689,749 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 54
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 5/31/26)
Portfolio structure
Equities 99.1%
Money Market Funds 0.9%
Equity sectors
Information Technology 40.1%
Financials 13.1%
Health Care 11.2%
Industrials 10.4%
Consumer Discretionary 9.8%
Communication Services 7.3%
Consumer Staples 4.2%
Utilities 2.0%
Materials 0.9%
Real Estate 0.1%
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
C000002024 [Member]  
Shareholder Report [Line Items]  
Fund Name Massachusetts InvestorsGrowth Stock Fund
Class Name Class R3
Trading Symbol MIGHX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about Massachusetts Investors Growth Stock Fund for the period of December 1, 2025 to May 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R3 $35 0.71%
Expenses Paid, Amount $ 35
Expense Ratio, Percent 0.71%
Net Assets $ 9,167,689,749
Holdings Count | Holding 54
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 5/31/26
Net Assets ($): 9,167,689,749 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 54
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 5/31/26)
Portfolio structure
Equities 99.1%
Money Market Funds 0.9%
Equity sectors
Information Technology 40.1%
Financials 13.1%
Health Care 11.2%
Industrials 10.4%
Consumer Discretionary 9.8%
Communication Services 7.3%
Consumer Staples 4.2%
Utilities 2.0%
Materials 0.9%
Real Estate 0.1%
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
C000002036 [Member]  
Shareholder Report [Line Items]  
Fund Name Massachusetts InvestorsGrowth Stock Fund
Class Name Class R2
Trading Symbol MIRGX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about Massachusetts Investors Growth Stock Fund for the period of December 1, 2025 to May 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R2 $48 0.97%
Expenses Paid, Amount $ 48
Expense Ratio, Percent 0.97%
Net Assets $ 9,167,689,749
Holdings Count | Holding 54
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 5/31/26
Net Assets ($): 9,167,689,749 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 54
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 5/31/26)
Portfolio structure
Equities 99.1%
Money Market Funds 0.9%
Equity sectors
Information Technology 40.1%
Financials 13.1%
Health Care 11.2%
Industrials 10.4%
Consumer Discretionary 9.8%
Communication Services 7.3%
Consumer Staples 4.2%
Utilities 2.0%
Materials 0.9%
Real Estate 0.1%
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
C000002034 [Member]  
Shareholder Report [Line Items]  
Fund Name Massachusetts InvestorsGrowth Stock Fund
Class Name Class R1
Trading Symbol MIGMX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about Massachusetts Investors Growth Stock Fund for the period of December 1, 2025 to May 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
R1 $73 1.47%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.47%
Net Assets $ 9,167,689,749
Holdings Count | Holding 54
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 5/31/26
Net Assets ($): 9,167,689,749 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 54
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 5/31/26)
Portfolio structure
Equities 99.1%
Money Market Funds 0.9%
Equity sectors
Information Technology 40.1%
Financials 13.1%
Health Care 11.2%
Industrials 10.4%
Consumer Discretionary 9.8%
Communication Services 7.3%
Consumer Staples 4.2%
Utilities 2.0%
Materials 0.9%
Real Estate 0.1%
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
C000002031 [Member]  
Shareholder Report [Line Items]  
Fund Name Massachusetts InvestorsGrowth Stock Fund
Class Name Class I
Trading Symbol MGTIX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about Massachusetts Investors Growth Stock Fund for the period of December 1, 2025 to May 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
I $23 0.47%
Expenses Paid, Amount $ 23
Expense Ratio, Percent 0.47%
Net Assets $ 9,167,689,749
Holdings Count | Holding 54
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 5/31/26
Net Assets ($): 9,167,689,749 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 54
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 5/31/26)
Portfolio structure
Equities 99.1%
Money Market Funds 0.9%
Equity sectors
Information Technology 40.1%
Financials 13.1%
Health Care 11.2%
Industrials 10.4%
Consumer Discretionary 9.8%
Communication Services 7.3%
Consumer Staples 4.2%
Utilities 2.0%
Materials 0.9%
Real Estate 0.1%
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
C000002030 [Member]  
Shareholder Report [Line Items]  
Fund Name Massachusetts InvestorsGrowth Stock Fund
Class Name Class C
Trading Symbol MIGDX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about Massachusetts Investors Growth Stock Fund for the period of December 1, 2025 to May 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
C $73 1.47%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.47%
Net Assets $ 9,167,689,749
Holdings Count | Holding 54
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 5/31/26
Net Assets ($): 9,167,689,749 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 54
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 5/31/26)
Portfolio structure
Equities 99.1%
Money Market Funds 0.9%
Equity sectors
Information Technology 40.1%
Financials 13.1%
Health Care 11.2%
Industrials 10.4%
Consumer Discretionary 9.8%
Communication Services 7.3%
Consumer Staples 4.2%
Utilities 2.0%
Materials 0.9%
Real Estate 0.1%
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
C000002029 [Member]  
Shareholder Report [Line Items]  
Fund Name Massachusetts InvestorsGrowth Stock Fund
Class Name Class B
Trading Symbol MIGBX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about Massachusetts Investors Growth Stock Fund for the period of December 1, 2025 to May 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
B $73 1.47%
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.47%
Net Assets $ 9,167,689,749
Holdings Count | Holding 54
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 5/31/26
Net Assets ($): 9,167,689,749 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 54
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 5/31/26)
Portfolio structure
Equities 99.1%
Money Market Funds 0.9%
Equity sectors
Information Technology 40.1%
Financials 13.1%
Health Care 11.2%
Industrials 10.4%
Consumer Discretionary 9.8%
Communication Services 7.3%
Consumer Staples 4.2%
Utilities 2.0%
Materials 0.9%
Real Estate 0.1%
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
C000002023 [Member]  
Shareholder Report [Line Items]  
Fund Name Massachusetts InvestorsGrowth Stock Fund
Class Name Class A
Trading Symbol MIGFX
Annual or Semi-Annual Statement [Text Block] This semiannual shareholder report contains important information about Massachusetts Investors Growth Stock Fund for the period of December 1, 2025 to May 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the fund at funds.mfs.com. You can also request this information by contacting us at 1‑800‑225‑2606 or by sending an e-mail request to orderliterature@mfs.com.
Additional Information Phone Number 1‑800‑225‑2606
Additional Information Email orderliterature@mfs.com
Additional Information Website funds.mfs.com
Expenses [Text Block]
FUND EXPENSES
What were the fund costs for the last six months?
(based on a hypothetical $10,000 investment)
Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment (annualized)
A $35 0.71%
Expenses Paid, Amount $ 35
Expense Ratio, Percent 0.71%
Net Assets $ 9,167,689,749
Holdings Count | Holding 54
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
FUND STATISTICS AS OF 5/31/26
Net Assets ($): 9,167,689,749 Portfolio Turnover Rate (%): 16
Total Number of Holdings: 54
Where the fund holds derivatives, they are not included in the total number of portfolio holdings.
Holdings [Text Block]
PORTFOLIO COMPOSITION (BASED ON TOTAL INVESTMENTS AS OF 5/31/26)
Portfolio structure
Equities 99.1%
Money Market Funds 0.9%
Equity sectors
Information Technology 40.1%
Financials 13.1%
Health Care 11.2%
Industrials 10.4%
Consumer Discretionary 9.8%
Communication Services 7.3%
Consumer Staples 4.2%
Utilities 2.0%
Materials 0.9%
Real Estate 0.1%
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%
MFS uses the Global Industry Classification Standard (GICS®) for sector/industry reporting. MFS has applied its own internal sector/industry classification methodology for equity securities and non-equity securities that are unclassified by GICS.
Largest Holdings [Text Block]
Top ten holdings
NVIDIA Corp. 12.7%
Microsoft Corp. 9.5%
Alphabet, Inc., "A" 5.9%
Apple, Inc. 5.3%
Amazon.com, Inc. 4.8%
Taiwan Semiconductor Manufacturing Co. Ltd., ADR 4.1%
Visa, Inc., "A" 3.5%
Amphenol Corp., "A" 3.3%
Aon PLC 2.4%
Moody's Corp. 2.4%