Document and Entity Information	Total
Prospectus:
Document Type	485BPOS
Document Period End Date	Oct. 31, 2022
Entity Registrant Name	MFS® SERIES TRUST X
Entity Central Index Key	0000783740
Entity Inv Company Type	N-1A
Amendment Flag	false
Document Creation Date	Feb. 27, 2023
Document Effective Date	Feb. 28, 2023
Prospectus Date	Feb. 28, 2023
MFS Emerging Markets Debt Local Currency Fund \| B
Prospectus:
Trading Symbol	EMLBX
MFS Emerging Markets Debt Local Currency Fund \| C
Prospectus:
Trading Symbol	EMLCX
MFS Emerging Markets Debt Local Currency Fund \| I
Prospectus:
Trading Symbol	EMLIX
MFS Emerging Markets Debt Local Currency Fund \| R1
Prospectus:
Trading Symbol	EMLJX
MFS Emerging Markets Debt Local Currency Fund \| R2
Prospectus:
Trading Symbol	EMLKX
MFS Emerging Markets Debt Local Currency Fund \| R3
Prospectus:
Trading Symbol	EMLLX
MFS Emerging Markets Debt Local Currency Fund \| R4
Prospectus:
Trading Symbol	EMLMX
MFS Emerging Markets Debt Local Currency Fund \| R6
Prospectus:
Trading Symbol	EMLNX
MFS Emerging Markets Debt Local Currency Fund \| A
Prospectus:
Trading Symbol	EMLAX

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