Nano Banana (Gemini 2.5 Flash Image) vs Gemini 3.1 Pro Preview Custom Tools
Nano Banana (Gemini 2.5 Flash Image) costs 4.8x less per output token than Gemini 3.1 Pro Preview Custom Tools ($2.50 vs $12.00 per million). Updated October 21, 2026; no benchmark has tested both models yet.
- Coding
- No data
- Overall
- No data
- Output $/M
- $2.50
- Coding
- No data
- Overall
- No data
- Output $/M
- $12.00
Nano Banana (Gemini 2.5 Flash Image) or Gemini 3.1 Pro Preview Custom Tools: which to pick
Neither model has a coding score yet, so the two cannot be ranked on coding.
Pick Nano Banana (Gemini 2.5 Flash Image) for output tokens 4.8x cheaper ($2.50 vs $12.00 per million).
No benchmark has tested both yet. Nano Banana (Gemini 2.5 Flash Image) has results on Design Arena: images, Design Arena: graphic design and Design Arena: logos; Gemini 3.1 Pro Preview Custom Tools on Vending-Bench 2. Compare them on price and context instead.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Neither has a coding score yet.
One side not measured
Image generation
Design Arena: images
No call
Only Nano Banana (Gemini 2.5 Flash Image) has a Design Arena: images result, 1179.
Directional only
Long documents
Listed context window
Gemini 3.1 Pro Preview Custom Tools
Gemini 3.1 Pro Preview Custom Tools takes 1.05M tokens against 33K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Nano Banana (Gemini 2.5 Flash Image)
Nano Banana (Gemini 2.5 Flash Image) $0.0015, Gemini 3.1 Pro Preview Custom Tools $0.0080 per turn.
List prices
At a glance
- Coding index
- Nano Banana (Gemini 2.5 Flash Image) not benchmarked, Gemini 3.1 Pro Preview Custom Tools not benchmarked.
- Widest category
- None yet: no category has been tested on both models.
- Widest single gap
- None yet: no benchmark has tested both models.
- Output price
- Nano Banana (Gemini 2.5 Flash Image) $2.50 against Gemini 3.1 Pro Preview Custom Tools $12.00 per million output tokens, 4.8x apart.
- Context window
- Nano Banana (Gemini 2.5 Flash Image) takes 33K tokens, Gemini 3.1 Pro Preview Custom Tools 1.05M.
Benchmark by benchmark
Every board either model has a result on, a category to a fold; bars are each result on a 0 to 100 scale. Only one model is measured on each, so no row names a leader.
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index1 board measured
| Benchmark | Nano Banana (Gemini 2.5 Flash Image) | Gemini 3.1 Pro Preview Custom Tools | Leader |
|---|---|---|---|
| Vending-Bench 2 | Not measured | $3,774 | Only Gemini 3.1 Pro Preview Custom Tools measured |
| Neither model has a result on the other 40 boards here | |||
Image generationDirectional onlyPublic boards, shown as published, kept out of the index3 boards measured
| Benchmark | Nano Banana (Gemini 2.5 Flash Image) | Gemini 3.1 Pro Preview Custom Tools | Leader |
|---|---|---|---|
| Design Arena: images | 1179 | Not measured | Only Nano Banana (Gemini 2.5 Flash Image) measured |
| Design Arena: graphic design | 1151 | Not measured | Only Nano Banana (Gemini 2.5 Flash Image) measured |
| Design Arena: logos | 1169 | Not measured | Only Nano Banana (Gemini 2.5 Flash Image) measured |
| Neither model has a result on the other 2 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Nano Banana (Gemini 2.5 Flash Image) costs less
Repository review
50K input + 3K output tokens
Nano Banana (Gemini 2.5 Flash Image) costs less
Agent loop
200K input + 10K output tokens
Nano Banana (Gemini 2.5 Flash Image) costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Google Nano Banana (Gemini 2.5 Flash Image) | Google Gemini 3.1 Pro Preview Custom Tools |
|---|---|---|
| Maker | ||
| Weights | No public weights listed | No public weights listed |
| Released | October 7, 2025 | February 25, 2026 |
| Context window | 33K | 1.05M |
| Input $/Mtok | $0.30 | $2.00 |
| Output $/Mtok | $2.50 | $12.00 |
| Coding index | Not benchmarked | Not benchmarked |
| Independent measurements behind it | 0 | 0 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Nano Banana (Gemini 2.5 Flash Image) better than Gemini 3.1 Pro Preview Custom Tools for coding?
Neither model has a coding score yet, so the two cannot be ranked on coding. Pick Nano Banana (Gemini 2.5 Flash Image) for output tokens 4.8x cheaper ($2.50 vs $12.00 per million).
Which is cheaper, Nano Banana (Gemini 2.5 Flash Image) or Gemini 3.1 Pro Preview Custom Tools?
Nano Banana (Gemini 2.5 Flash Image) costs $0.30 per million input tokens and $2.50 per million output tokens; Gemini 3.1 Pro Preview Custom Tools costs $2.00 and $12.00. Cost per solved task is known for neither of them.
Which has the bigger context window, Nano Banana (Gemini 2.5 Flash Image) or Gemini 3.1 Pro Preview Custom Tools?
Gemini 3.1 Pro Preview Custom Tools, with 1.05M tokens against 33K.
Has any benchmark tested both Nano Banana (Gemini 2.5 Flash Image) and Gemini 3.1 Pro Preview Custom Tools?
No benchmark has tested both yet. Nano Banana (Gemini 2.5 Flash Image) has results on Design Arena: images, Design Arena: graphic design and Design Arena: logos; Gemini 3.1 Pro Preview Custom Tools on Vending-Bench 2. Compare them on price and context instead. Data as of October 21, 2026.