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Claude Sonnet 5.5 vs GLM-5.3-Flash

Claude Sonnet 5.5Anthropic
GLM-5.3-FlashZ.ai
Our take

Claude Sonnet 5.5 wins 4 of 4 categories, but GLM-5.3-Flash is 16.8× cheaper for everyday text work. Pick Claude Sonnet 5.5 when quality matters most, GLM-5.3-Flash at volume.

Overall79Best55
Coding87Best69
Writing74Best64
Support69Best67
Value69Best60
Input / 1M$2.00$0.15Best
Output / 1M$10.00$0.50Best
Blended / 1M$4.00$0.24Best
Context window1M1M
Open weightsNoYes
Released28 Sept 202626 Aug 2026

Your monthly bill

50k
Claude Sonnet 5.5$800
GLM-5.3-Flash$47.50Cheapest
List prices, a quarter of the tokens as output. Scores are provisional, from Arena and Epoch AI.