API cost decision in 10 seconds

🔥Gemini 2.5 Flash vs 🔥GLM 5.1

Pick Gemini 2.5 Flash when budget and context both matter.

Pricing data updated: 2026-05-15T02:08:14Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Gemini 2.5 Flash when budget and context both matter.

On the standard 1M input plus 500K output workload, Gemini 2.5 Flash is estimated at $1.55 vs $2.52 for GLM 5.1, saving $0.97 (38.5% lower).

Cost-first pickGemini 2.5 Flash

Context-first pickGemini 2.5 Flash

Sample savings$0.9738.5%

10x traffic gap$9.7

Gemini 2.5 Flash is cheaper on the standard workload and also has the larger context window. At 10x that traffic, the same price gap is about $9.7. Use the calculator below to replace the sample workload with your own token volume.

Cheaper input Gemini 2.5 Flash $0.3 vs $0.98 / 1M

Gemini 2.5 Flash is $0.68 cheaper per 1M input tokens (69.4% lower; 3.27x difference).

Cheaper output Gemini 2.5 Flash $2.5 vs $3.08 / 1M

Gemini 2.5 Flash is $0.58 cheaper per 1M output tokens (18.8% lower; 1.23x difference).

Larger context Gemini 2.5 Flash 1.05M vs 202.75K

Gemini 2.5 Flash has 845.82K more context (5.17x larger).

Sample workload Gemini 2.5 Flash $1.55 vs $2.52

Gemini 2.5 Flash is $0.97 cheaper on the standard workload (38.5% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Gemini 2.5 Flash Calculating… Estimated API cost

GLM 5.1 Calculating… Estimated API cost

Cheaper for this workload Calculating… Difference: calculating…

This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.

Quick Decision

Verdict

Gemini 2.5 Flash has the lower input price; Gemini 2.5 Flash has the lower output price; Gemini 2.5 Flash offers the larger context window. For the 1M input plus 500K output sample, Gemini 2.5 Flash is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $1.55 for Gemini 2.5 Flash and $2.52 for GLM 5.1.

Best Fit

Choose Gemini 2.5 Flash when you care most about lower input-token price, lower output-token price, and larger context window.

Choose GLM 5.1 when its provider, model quality, latency, or availability is more important than the numeric price/context winner.

Decision Notes

On the standard 1M input plus 500K output workload, Gemini 2.5 Flash is estimated at $1.55 vs $2.52 for GLM 5.1, saving $0.97 (38.5% lower).
Gemini 2.5 Flash is $0.97 cheaper on the standard workload (38.5% lower).
Gemini 2.5 Flash is $0.68 cheaper per 1M input tokens (69.4% lower; 3.27x difference).
Gemini 2.5 Flash is $0.58 cheaper per 1M output tokens (18.8% lower; 1.23x difference).
Gemini 2.5 Flash has 845.82K more context (5.17x larger).

Head-to-Head Specs

Feature	🔥Gemini 2.5 Flash (Google)	🔥GLM 5.1 (Z.ai)
Input Price prompt tokens per 1M	$0.3	$0.98
Completion Price per 1M tokens	$2.5	$3.08
Sample Workload Cost 1M input + 500K output	$1.55	$2.52
Context Window	1.05M	202.75K
Release Date	2025-06-17	2026-04-07
Popularity Rank current rank	#15	#20

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Gemini 2.5 Flash	On the standard 1M input plus 500K output workload, Gemini 2.5 Flash is estimated at $1.55 vs $2.52 for GLM 5.1, saving $0.97 (38.5% lower).
High-volume input processing	Gemini 2.5 Flash	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Gemini 2.5 Flash	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Gemini 2.5 Flash	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

Gemma 4 26B A4B (free) can replace Gemini 2.5 Flash when lower sample workload cost matters most: $0.
Gemma 4 31B (free) can replace Gemini 2.5 Flash when lower sample workload cost matters most: $0.
Lyria 3 Pro Preview can replace Gemini 2.5 Flash when lower sample workload cost matters most: $0.
Lyria 3 Clip Preview can replace Gemini 2.5 Flash when lower sample workload cost matters most: $0.

Larger context near this budget

Grok 4.1 Fast offers 2M context with $0.45 sample workload cost.
Grok 4.20 offers 2M context with $2.5 sample workload cost.
Grok 4 Fast offers 2M context with $0.45 sample workload cost.
Owl Alpha offers 1.05M context with $0 sample workload cost.

Popular competitors

Hy3 preview · Tencent · #1
Claude Opus 4.7 · Anthropic · #2
Claude Sonnet 4.6 · Anthropic · #3
DeepSeek V4 Flash · DeepSeek · #4

Cheaper alternatives

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Larger context alternatives

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Provider catalogs

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Google catalog

Review all tracked Google models before deciding whether this matchup is the right shortlist.

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Z.ai catalog

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Gemini 2.5 Flash

Gemini 2.5 Flash is Google's state-of-the-art workhorse model, specifically designed for advanced reasoning, coding, mathematics, and scientific tasks. It includes built-in "thinking" capabilities, enabling it to provide responses with greater...

GLM 5.1

GLM-5.1 delivers a major leap in coding capability, with particularly significant gains in handling long-horizon tasks. Unlike previous models built around minute-level interactions, GLM-5.1 can work independently and continuously on...