Model comparison
Gemini 2.5 Pro vs Gemini 3.1 Pro
Two Google tiers compared on the figures that decide which one a workload actually needs.
Catalog record checked September 5, 2026Individual provider fields may changeEvidence confidence: High — see receipts below
Gemini 2.5 Pro
Balanced
Gemini 3.1 Pro
Frontier
| Specification | Gemini 2.5 Pro | Gemini 3.1 Pro |
|---|---|---|
| Provider | ||
| Tier | Balanced | Frontier |
| Context window | 1.05M | 1.05M |
| Max output | 66K | 66K |
| Input / 1M tokens | Winner: $1.25 | $2 |
| Output / 1M tokens | Winner: $10 | $12 |
| Weights | Closed | Closed |
| Parameters | Not disclosedUnverified | Not disclosedUnverified |
| Reasoning levels | low, medium, high | low, medium, high |
| Modalities | text, image, video, audio, pdf | text, image, video, audio, pdf |
| API model id | gemini-2.5-pro | gemini-3.1-pro-preview |
| Released | June 17, 2025 | February 19, 2026 |
| Artificial Analysis Intelligence Index (2026-08-14) | 47 | Winner: 60 |
| SWE-bench Verified (2026-02) | Not verifiedUnverified | 80.6 |
| GPQA Diamond (2026-02) | Not verifiedUnverified | 94.3 |
| Humanity's Last Exam (2026-02) | Not verifiedUnverified | 44.4 |
| Terminal-Bench 2.1 (2026-07) | Not verifiedUnverified | 73.8 |
Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.
Benchmark receipts
- 2026-08-14: Artificial AnalysisComposite index blending reasoning, knowledge, and coding evals into one 0–100 score. Comparability: directly comparable — AA occasionally rebaselines the index scale between snapshots — a score captured on one date is only comparable to same-snapshot scores (check measuredAt).
- 2026-07: Google DeepMind model evaluation report (vendor, Terminus-2; own Feb report separately reported TB 2.0 = 68.5 — versions preserved)Agentic terminal work: multi-step tasks executed in a sandboxed shell environment. Comparability: comparable with caveat — Scores across Terminal-Bench major versions (v1 vs v2) are NOT comparable; harness configuration (container, time limits) also shifts results.
- 2026-02: Google DeepMind model evaluation report (vendor, no tools; 51.4 with search+code)Real GitHub issue resolution: does the model's patch pass the hidden tests. Comparability: comparable with caveat — Post-audit vendor claims and pre-audit scores sit on different task trust levels; scaffolding (agent harness, compute budget) also dominates results. Never aggregate across scaffolds.
Pricing tiers: Gemini 2.5 Pro: $1.25/$10 per MTok (≤200K); $2.50/$15 (>200K). Legacy but still widely listed. · Gemini 3.1 Pro: $2/$12 per MTok (≤200K); $4/$18 (>200K). Still 'Preview' as of 2026-08-29; 3.5 Pro not yet released.
Gemini 2.5 Pro
Gemini 2.5 Pro is Google's previous-generation Pro with a 1.05M-token context and strong multimodal support.
Best for
- Long documents
- Multimodal input
- Google Workspace integration
Watch out
A generation behind Gemini 3.x; verify on your workload.
Gemini 3.1 Pro
Gemini 3.1 Pro is Google's current flagship Pro model with record benchmark scores and a 1M-token context.
Best for
- Very long documents
- Multimodal reasoning
- Frontier knowledge work
Watch out
Still in Preview; 3.5 Pro is 'coming soon' but unreleased as of 2026-08-29.
When the cheaper one wins
Gemini 2.5 Pro is cheaper on output at $10 per million tokens against $12 for Gemini 3.1 Pro — about 1.2×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.
Run the model pickerEvidence confidence: High
How strong and complete the evidence behind this comparison is — not a prediction of which model is better.
- Pricing verified on both sides — Input and output rates are verified for both models.
- 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
- 1 shared named benchmark with differing scores — Measured on: Artificial Analysis Intelligence Index.
- Verified within the last 90 days — Newest catalog check was 6 days ago.
- Both models carry source citations — Each side has at least two catalog sources on record.
Source receipts
Each catalog figure was checked against the provider or an independent second source on the date shown.
- Gemini 2.5 Pro: Google — Gemini 2.5 Pro GA (accessed 2026-08-29)
- Gemini 2.5 Pro: Google AI pricing (accessed 2026-08-29)
- Gemini 3.1 Pro: Google Cloud — Gemini 3.1 Pro (accessed 2026-08-29)
- Gemini 3.1 Pro: TechCrunch — Gemini 3.1 Pro (accessed 2026-08-29)
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- Claude Fable 5 vs Gemini 3.1 Pro
- Claude Mythos 5.1 vs Gemini 3.1 Pro
- Claude Opus 5 vs Gemini 3.1 Pro
- Claude Sonnet 5 vs Gemini 2.5 Pro
Diving deeper on one model? Gemini 2.5 Pro · Gemini 3.1 Pro
Common questions
Gemini 2.5 Pro vs Gemini 3.1 Pro
Answered from the verified figures on this page rather than general guidance.
Is Gemini 2.5 Pro or Gemini 3.1 Pro cheaper for input?
Gemini 2.5 Pro is cheaper at $1.25 per million input tokens, against $2 for Gemini 3.1 Pro — roughly 1.6× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Gemini 2.5 Pro has tiered pricing: $1.25/$10 per MTok (≤200K); $2.50/$15 (>200K). Legacy but still widely listed. Gemini 3.1 Pro has tiered pricing: $2/$12 per MTok (≤200K); $4/$18 (>200K). Still 'Preview' as of 2026-08-29; 3.5 Pro not yet released.
Is Gemini 2.5 Pro or Gemini 3.1 Pro cheaper for output?
Gemini 2.5 Pro is cheaper at $10 per million output tokens, against $12 for Gemini 3.1 Pro — roughly 1.2× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Gemini 2.5 Pro has tiered pricing: $1.25/$10 per MTok (≤200K); $2.50/$15 (>200K). Legacy but still widely listed. Gemini 3.1 Pro has tiered pricing: $2/$12 per MTok (≤200K); $4/$18 (>200K). Still 'Preview' as of 2026-08-29; 3.5 Pro not yet released.
Which has the larger context window, Gemini 2.5 Pro or Gemini 3.1 Pro?
Both accept about 1.05M tokens of context, so document length will not decide between them.
Do Gemini 2.5 Pro and Gemini 3.1 Pro support the same reasoning levels?
Yes — both accept the same effort settings: "low", "medium", "high". Higher effort costs more and takes longer, so start low and raise it only where output quality actually improves.
Should I use Gemini 2.5 Pro or Gemini 3.1 Pro?
Gemini 2.5 Pro is the balanced tier and Gemini 3.1 Pro the frontier tier. The useful question is whether your hardest task actually fails on the cheaper one — most production volume such as classification, extraction and summarisation does not.
Next step
Choosing between them
The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.
- Input price: Gemini 2.5 Pro costs $1.25 per 1M tokens versus $2 for Gemini 3.1 Pro — a 1.6x difference at the headline tier.
- Measured capability: Gemini 3.1 Pro leads Artificial Analysis Intelligence Index 60 to 47 (measured 2026-08-14).
- Positioning: Gemini 2.5 Pro sits in the balanced tier, Gemini 3.1 Pro in the frontier tier — most production volume (classification, extraction, summarisation) does not need the pricier tier.
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