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Gemini 3.7 Flash vs GLM-5.3: API Cost Comparison

Gemini 3.7 Flash is cheaper than GLM-5.3 while the promo runs ($0.75/$3.75 vs $1.40/$4.40) and keeps a deeper cache discount and a batch tier. After January 2027 GLM-5.3's flat rate wins on both rows.

Gemini 3.7 Flash's promo rate undercuts GLM-5.3 by nearly half through the end of 2026, but the sunset on January 1, 2027 flips the ranking. The right pick depends on when your workload runs and how cache-heavy it is.

By TechCompare · Updated

Input tokens
100,000
per request
Output tokens
5,000
per request
Volume
100 / monthly
Standard API

Calculator

Cost Comparison

Based on 100,000 input tokens (50% cached), 5,000 output tokens, and 100 requests.Prices are fetched live from OpenRouter and may include temporary promotional discounts not accounted for in our article and comparison figures.

Same 100,000 in / 5,000 out (50% cached) scenario, pre-loaded. Adjust tokens, caching, or swap models.
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How this is calculated

Gemini 3.7 Flash is $0.75 per million input and $3.75 per million output on promo through December 31, 2026 (standard: $1.50/$7.50), with 90% caching and 50% batch. GLM-5.3 is flat $1.40/$4.40 with ~81% caching and no batch tier. Both offer 1M context windows.

Verdict

At promo rates a 100K + 5K call is $0.094 on Flash versus $0.162 on GLM-5.3, and cache-heavy loops gap further since Flash's cached input is $0.075/M against GLM's $0.26/M. Batch jobs take 50% off on Flash, which GLM simply doesn't offer. The catch is the January 1, 2027 reset: Flash reverts to $1.50/$7.50 and GLM-5.3 becomes cheaper on output by 41%. Choose Flash now if the workload ships this year, and re-model the bill before Q1 when the promo expires.

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Frequently asked questions

Which is cheaper today, Gemini 3.7 Flash or GLM-5.3?
Gemini 3.7 Flash at promo: $0.75/$3.75 versus GLM-5.3's $1.40/$4.40, roughly 46% cheaper on both rows. Cached input is also cheaper on Flash ($0.075/M vs $0.26/M) and Flash has a 50% batch tier.
What happens to the comparison after December 2026?
Gemini 3.7 Flash reverts to $1.50/$7.50 standard pricing on January 1, 2027. GLM-5.3 stays flat at $1.40/$4.40, so GLM becomes cheaper on both rows and especially on output, where $4.40 beats $7.50 by 41%.
Which has the better prompt cache economics?
Gemini 3.7 Flash. Its 90% cache discount lands cached input at $0.075/M (plus $0.50/M-hour storage for persistent caches), while GLM-5.3's 81% discount lands at $0.26/M. For agent loops with stable prompts, Flash costs about 3.5x less on cached input.

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