API cost decision in 10 seconds

Nano Banana (Gemini 2.5 Flash Image) vs Gemini 3.1 Pro Preview Custom Tools

Pick Nano Banana (Gemini 2.5 Flash Image) for lower cost; pick Gemini 3.1 Pro Preview Custom Tools only if the larger context window matters more.

Page updated: 2026-05-26T15:08:08Z Data confirmed: 2026-05-26T20:08:05Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Nano Banana (Gemini 2.5 Flash Image) for lower cost; pick Gemini 3.1 Pro Preview Custom Tools only if the larger context window matters more.

On the standard 1M input plus 500K output workload, Nano Banana (Gemini 2.5 Flash Image) is estimated at $1.55 vs $8 for Gemini 3.1 Pro Preview Custom Tools, saving $6.45 (80.6% lower).

Cost-first pickNano Banana (Gemini 2.5 Flash Image)

Context-first pickGemini 3.1 Pro Preview Custom Tools

Sample savings$6.4580.6%

10x traffic gap$64.5

Gemini 3.1 Pro Preview Custom Tools has more context, but Nano Banana (Gemini 2.5 Flash Image) saves $6.45 on the standard workload. At 10x that traffic, the same price gap is about $64.5. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Nano Banana (Gemini 2.5 Flash Image) stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	Nano Banana (Gemini 2.5 Flash Image)	Gemini 3.1 Pro Preview Custom Tools
Input-heavy / RAG	5M input + 500K output	Nano Banana (Gemini 2.5 Flash Image)	$2.75	$16
Balanced workload	1M input + 1M output	Nano Banana (Gemini 2.5 Flash Image)	$2.8	$14
Output-heavy chatbot	1M input + 5M output	Nano Banana (Gemini 2.5 Flash Image)	$12.8	$62

Cheaper input Nano Banana (Gemini 2.5 Flash Image) $0.3 vs $2 / 1M

Nano Banana (Gemini 2.5 Flash Image) is $1.7 cheaper per 1M input tokens (85% lower; 6.67x difference).

Cheaper output Nano Banana (Gemini 2.5 Flash Image) $2.5 vs $12 / 1M

Nano Banana (Gemini 2.5 Flash Image) is $9.5 cheaper per 1M output tokens (79.2% lower; 4.8x difference).

Larger context Gemini 3.1 Pro Preview Custom Tools 32.77K vs 1.05M

Gemini 3.1 Pro Preview Custom Tools has 1.02M more context (32x larger).

Sample workload Nano Banana (Gemini 2.5 Flash Image) $1.55 vs $8

Nano Banana (Gemini 2.5 Flash Image) is $6.45 cheaper on the standard workload (80.6% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Nano Banana (Gemini 2.5 Flash Image) Calculating… Estimated API cost

Gemini 3.1 Pro Preview Custom Tools 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

Nano Banana (Gemini 2.5 Flash Image) has the lower input price; Nano Banana (Gemini 2.5 Flash Image) has the lower output price; Gemini 3.1 Pro Preview Custom Tools offers the larger context window. For the 1M input plus 500K output sample, Nano Banana (Gemini 2.5 Flash Image) is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $1.55 for Nano Banana (Gemini 2.5 Flash Image) and $8 for Gemini 3.1 Pro Preview Custom Tools.

Best Fit

Choose Nano Banana (Gemini 2.5 Flash Image) when you care most about lower input-token price, and lower output-token price.

Choose Gemini 3.1 Pro Preview Custom Tools when you care most about larger context window.

Decision Notes

On the standard 1M input plus 500K output workload, Nano Banana (Gemini 2.5 Flash Image) is estimated at $1.55 vs $8 for Gemini 3.1 Pro Preview Custom Tools, saving $6.45 (80.6% lower).
Nano Banana (Gemini 2.5 Flash Image) is $6.45 cheaper on the standard workload (80.6% lower).
Nano Banana (Gemini 2.5 Flash Image) is $1.7 cheaper per 1M input tokens (85% lower; 6.67x difference).
Nano Banana (Gemini 2.5 Flash Image) is $9.5 cheaper per 1M output tokens (79.2% lower; 4.8x difference).
Gemini 3.1 Pro Preview Custom Tools has 1.02M more context (32x larger).

Head-to-Head Specs

Feature	Nano Banana (Gemini 2.5 Flash Image) (Google)	Gemini 3.1 Pro Preview Custom Tools (Google)
Input Price prompt tokens per 1M	$0.3	$2
Completion Price per 1M tokens	$2.5	$12
Sample Workload Cost 1M input + 500K output	$1.55	$8
Context Window	32.77K	1.05M
Release Date	2025-10-07	2026-02-25
Popularity	#121	#132

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Nano Banana (Gemini 2.5 Flash Image)	On the standard 1M input plus 500K output workload, Nano Banana (Gemini 2.5 Flash Image) is estimated at $1.55 vs $8 for Gemini 3.1 Pro Preview Custom Tools, saving $6.45 (80.6% lower).
High-volume input processing	Nano Banana (Gemini 2.5 Flash Image)	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Nano Banana (Gemini 2.5 Flash Image)	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Gemini 3.1 Pro Preview Custom Tools	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

Gemma 4 31B (free) can replace Nano Banana (Gemini 2.5 Flash Image) when lower sample workload cost matters most: $0.
Gemma 4 26B A4B (free) can replace Nano Banana (Gemini 2.5 Flash Image) when lower sample workload cost matters most: $0.
Lyria 3 Clip Preview can replace Nano Banana (Gemini 2.5 Flash Image) when lower sample workload cost matters most: $0.
Lyria 3 Pro Preview can replace Nano Banana (Gemini 2.5 Flash Image) 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.
Grok 4.20 offers 2M context with $2.5 sample workload cost.
Grok 4.20 Multi-Agent offers 2M context with $5 sample workload cost.
GPT-5.4 offers 1.05M context with $10 sample workload cost.

Popular competitors

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

Open Google models

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