v3.26.1
Form N-1A Cover
Feb. 28, 2026
Prospectus [Line Items]  
Document Type 485BPOS
Amendment Flag false
Registrant Name MFS® SERIES TRUST XIII
Entity Central Index Key 0000356349
Entity Investment Company Type N-1A
Document Period End Date Feb. 28, 2026
Prospectus Date Jun. 26, 2026