Model comparison
Gemini 2.5 Flash vs GPT-5.5 Pro
GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 39.3 on the Noometry Index. Gemini 2.5 Flash costs 79× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.
Last verified . 10 shared benchmarks.
GoogleSummary
- They share 10 benchmarks with published results for both. Gemini 2.5 Flash scores higher in 0 categories and GPT-5.5 Pro in 3 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5.5 Pro leads 73.3 to 18.1.
- The biggest single-benchmark swing is ARC-AGI-2: 2.5% for Gemini 2.5 Flash and 84.6% for GPT-5.5 Pro.
- Gemini 2.5 Flash is cheaper at $0.30 / $2.50 per million input/output tokens, against $30 / $180 for GPT-5.5 Pro.
- GPT-5.5 Pro accepts more context: 1.05M tokens versus 1.05M.
Side by side
| Gemini 2.5 Flash | GPT-5.5 Pro | |
|---|---|---|
| Provider | OpenAI | |
| Noometry Index | 39.3 | 64.3 |
| Released | 2025-04-17 | 2026-04-23 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 1.05M |
| Max output | 66K | 128K |
| Input $ / M tokens | $0.30 | $30 |
| Output $ / M tokens | $2.50 | $180 |
| Results tracked | 54 | 14 |
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Category by category
Coding Not comparable
Gemini 2.5 Flash: 35.8 (#220), GPT-5.5 Pro: —
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| SWE-bench Verified (bash only) | 28.7% | — |
| Aider Polyglot | 55.1% | — |
| WeirdML | 41.9% | — |
| LMArena Coding | 1424 | — |
| ALE-Bench | 661.88 | — |
Agentic & Tool Use Not comparable
Gemini 2.5 Flash: 30.8 (#74), GPT-5.5 Pro: —
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| Terminal-Bench | 17.1% | — |
| Berkeley Function Calling Leaderboard | 56.2% | — |
| TheAgentCompany | 41.1% | — |
| BALROG | 33.5% | — |
| Vending-Bench 2 | 548.84 | — |
Reasoning GPT-5.5 Pro leads
Gemini 2.5 Flash: 18.1 (#286), GPT-5.5 Pro: 73.3 (#10)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| ARC-AGI-2 | 2.5% | 84.6% |
| SimpleBench | 41.2% | 76.9% |
| ARC-AGI-1 | 33.3% | 96.5% |
| CritPt | 1.1% | 30.6% |
| DTBench | 76.5% | 96% |
| LMCA | 27.5% | 53.9% |
| Epoch Capabilities Index | 143.03 | 162.07 |
| Kagi LLM Benchmark | 56.8% | — |
| Chess Puzzles | — | 64% |
| EnigmaEval | 2.7% | — |
| LMArena Hard Prompts | 1422 | — |
| ForecastBench | 60.6 | — |
Math GPT-5.5 Pro leads
Gemini 2.5 Flash: 39.9 (#98), GPT-5.5 Pro: 84.0 (#10)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 73.1% | 100% |
| FrontierMath (Feb 2025 set) | 4.8% | 52.4% |
| FrontierMath Tier 4 (v1) | 4.2% | 39.6% |
| FrontierMath (Tiers 1-3) | — | 87.7% |
| FrontierMath Tier 4 | — | 78% |
| Omni-MATH | 38.5% | — |
| LMArena Math | 1415 | — |
Knowledge GPT-5.5 Pro leads
Gemini 2.5 Flash: 36.4 (#168), GPT-5.5 Pro: 64.1 (#19)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| GPQA Diamond | — | 93.9% |
| Humanity's Last Exam | 12.1% | — |
| MMLU-Pro | 63.9% | — |
| Confabulations | 16.8% | — |
| Vectara Hallucination Rate | 7.8% | — |
| GPQA (HELM) | 39% | — |
| LMArena Expert | 1426 | — |
Multimodal Not comparable
Gemini 2.5 Flash: 41.8 (#32), GPT-5.5 Pro: —
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Vision | 1253 | — |
| GeoBench | 76% | — |
| VPCT | 46.2% | — |
| SpatialViz-Bench | 36.9% | — |
Multilingual Not comparable
Gemini 2.5 Flash: 52.3 (#88), GPT-5.5 Pro: —
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Non-English | 1409 | — |
| LMArena Chinese | 1450 | — |
| LMArena French | 1433 | — |
| LMArena German | 1418 | — |
| LMArena Japanese | 1405 | — |
| LMArena Korean | 1385 | — |
| LMArena Russian | 1415 | — |
| LMArena Spanish | 1421 | — |
Instruction Following Not comparable
Gemini 2.5 Flash: 75.7 (#54), GPT-5.5 Pro: —
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| IFEval | 89.8% | — |
| LMArena Instruction Following | 1405 | — |
Long Context Not comparable
Gemini 2.5 Flash: 47.5 (#17), GPT-5.5 Pro: —
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| Fiction.LiveBench | 77.8% | — |
| LMArena Longer Query | 1419 | — |
Writing & Preference Not comparable
Gemini 2.5 Flash: 53.8 (#157), GPT-5.5 Pro: —
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro |
|---|---|---|
| LMArena Text | 1417 | — |
| LMArena Creative Writing | 1400 | — |
| Short-Story Creative Writing | 76.5% | — |
| EQ-Bench Creative Writing | 1137 | — |
| WildBench | 81.7% | — |
| LMArena Multi-Turn | 1408 | — |
Frequently asked questions
Is Gemini 2.5 Flash better than GPT-5.5 Pro?
GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 39.3 on the Noometry Index. Gemini 2.5 Flash costs 79× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.
Which is cheaper, Gemini 2.5 Flash or GPT-5.5 Pro?
Gemini 2.5 Flash is cheaper. It lists at $0.30 per million input tokens and $2.50 per million output tokens; GPT-5.5 Pro lists at $30 and $180.
Which has the bigger context window?
GPT-5.5 Pro does, with 1.05M tokens against 1.05M.
How many benchmarks do Gemini 2.5 Flash and GPT-5.5 Pro share?
10 benchmarks have published results for both models. Gemini 2.5 Flash has 54 scored results on Noometry and GPT-5.5 Pro has 14.