v3.26.1
Earnings per Share ("EPS") (Tables)
 9 Months Ended
Jun. 28, 2026
Earnings Per Share [Abstract]  
Summary of number of weighted-average shares used to compute basic and diluted EPS
The following table presents the number of weighted-average shares used to compute basic and diluted EPS (in thousands, except per share data):
Three Months EndedNine Months Ended
June 28,
2026		June 29,
2025		June 28,
2026		June 29,
2025
Net income attributable to Tetra Tech$109,584 $113,844 $308,235 $119,979 
Weighted-average common shares outstanding – basic258,151 263,026 259,685 265,589 
Effect of dilutive stock options and unvested restricted stock1,628 1,829 1,774 1,900 
Shares issuable assuming conversion of convertible notes— — — 624 
Weighted-average common shares outstanding – diluted259,779 264,855 261,459 268,113 
Earnings per share attributable to Tetra Tech:
Basic$0.42 $0.43 $1.19 $0.45 
Diluted$0.42 $0.43 $1.18 $0.45