API cost decision in 10 seconds

🔥GLM 5.1 vs 🔥Gemini 3.1 Flash Lite Preview

Pick GLM 5.1 for lower cost; pick Gemini 3.1 Flash Lite Preview only if the larger context window matters more.

Pricing data updated: 2026-05-21T06:08:05Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick GLM 5.1 for lower cost; pick Gemini 3.1 Flash Lite Preview only if the larger context window matters more.

On the standard 1M input plus 500K output workload, GLM 5.1 is estimated at $0 vs $1 for Gemini 3.1 Flash Lite Preview, saving $1 (100% lower).

Cost-first pickGLM 5.1

Context-first pickGemini 3.1 Flash Lite Preview

Sample savings$1100%

10x traffic gap$10

Gemini 3.1 Flash Lite Preview has more context, but GLM 5.1 saves $1 on the standard workload. At 10x that traffic, the same price gap is about $10. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

GLM 5.1 stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	GLM 5.1	Gemini 3.1 Flash Lite Preview
Input-heavy / RAG	5M input + 500K output	GLM 5.1	$0	$2
Balanced workload	1M input + 1M output	GLM 5.1	$0	$1.75
Output-heavy chatbot	1M input + 5M output	GLM 5.1	$0	$7.75

Cheaper input GLM 5.1 $0 vs $0.25 / 1M

GLM 5.1 is free for input tokens while Gemini 3.1 Flash Lite Preview costs $0.25 per 1M tokens.

Cheaper output GLM 5.1 $0 vs $1.5 / 1M

GLM 5.1 is free for output tokens while Gemini 3.1 Flash Lite Preview costs $1.5 per 1M tokens.

Larger context Gemini 3.1 Flash Lite Preview 202.8K vs 1.05M

Gemini 3.1 Flash Lite Preview has 845.78K more context (5.17x larger).

Sample workload GLM 5.1 $0 vs $1

GLM 5.1 is free for the standard workload while the other model is estimated at $1.

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

GLM 5.1 Calculating… Estimated API cost

Gemini 3.1 Flash Lite Preview 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

GLM 5.1 has the lower input price; GLM 5.1 has the lower output price; Gemini 3.1 Flash Lite Preview offers the larger context window. For the 1M input plus 500K output sample, GLM 5.1 is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $0 for GLM 5.1 and $1 for Gemini 3.1 Flash Lite Preview.

Best Fit

Choose GLM 5.1 when you care most about lower input-token price, and lower output-token price.

Choose Gemini 3.1 Flash Lite Preview when you care most about larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, GLM 5.1 is estimated at $0 vs $1 for Gemini 3.1 Flash Lite Preview, saving $1 (100% lower).
GLM 5.1 is free for the standard workload while the other model is estimated at $1.
GLM 5.1 is free for input tokens while Gemini 3.1 Flash Lite Preview costs $0.25 per 1M tokens.
GLM 5.1 is free for output tokens while Gemini 3.1 Flash Lite Preview costs $1.5 per 1M tokens.
Gemini 3.1 Flash Lite Preview has 845.78K more context (5.17x larger).

Head-to-Head Specs

Feature	🔥GLM 5.1 (Z.ai)	🔥Gemini 3.1 Flash Lite Preview (Google)
Input Price prompt tokens per 1M	$0	$0.25
Completion Price per 1M tokens	$0	$1.5
Sample Workload Cost 1M input + 500K output	$0	$1
Context Window	202.8K	1.05M
Release Date	2026-04-07	2026-03-03
Popularity	#19	#20

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	GLM 5.1	On the standard 1M input plus 500K output workload, GLM 5.1 is estimated at $0 vs $1 for Gemini 3.1 Flash Lite Preview, saving $1 (100% lower).
High-volume input processing	GLM 5.1	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	GLM 5.1	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Gemini 3.1 Flash Lite Preview	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 3.1 Flash Lite Preview when lower sample workload cost matters most: $0.
Gemma 4 31B (free) can replace Gemini 3.1 Flash Lite Preview when lower sample workload cost matters most: $0.
Lyria 3 Pro Preview can replace Gemini 3.1 Flash Lite Preview when lower sample workload cost matters most: $0.
Lyria 3 Clip Preview can replace Gemini 3.1 Flash Lite Preview when lower sample workload cost matters most: $0.

Larger context near this budget

Llama 4 Scout offers 10M context with $0.23 sample workload cost.
Owl Alpha offers 1.05M context with $0 sample workload cost.

Popular competitors

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

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Z.ai catalog

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Google catalog

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Gemini 3.1 Flash Lite Preview is Google's high-efficiency model optimized for high-volume use cases. It outperforms Gemini 2.5 Flash Lite on overall quality and approaches Gemini 2.5 Flash performance across...