Model comparison
Gemini 2.5 Flash vs GPT-5.5 Instant
GPT-5.5 Instant is the stronger model overall, scoring 42.5 to 39.0 on the Noometry Index.
Last verified . 21 shared benchmarks.
GoogleSummary
- They share 21 benchmarks with published results for both. Gemini 2.5 Flash scores higher in 4 categories and GPT-5.5 Instant in 5 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where GPT-5.5 Instant leads 48.9 to 36.1.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 73.1% for Gemini 2.5 Flash and 68.1% for GPT-5.5 Instant.
Side by side
| Gemini 2.5 Flash | GPT-5.5 Instant | |
|---|---|---|
| Provider | OpenAI | |
| Noometry Index | 39.0 | 42.5 |
| Released | 2025-04-17 | 2026-05-05 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | — |
| Max output | 66K | — |
| Input $ / M tokens | $0.30 | — |
| Output $ / M tokens | $2.50 | — |
| Results tracked | 54 | 27 |
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Category by category
Coding GPT-5.5 Instant leads
Gemini 2.5 Flash: 35.5 (#210), GPT-5.5 Instant: 43.7 (#73)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| LMArena Coding | 1424 | 1433 |
| SWE-bench Verified (bash only) | 28.7% | — |
| Aider Polyglot | 55.1% | — |
| SciCode | — | 48.6% |
| WeirdML | 41.9% | — |
| ALE-Bench | 661.88 | — |
Agentic & Tool Use Not comparable
Gemini 2.5 Flash: 30.6 (#67), GPT-5.5 Instant: —
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| 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 Instant leads
Gemini 2.5 Flash: 18.2 (#271), GPT-5.5 Instant: 24.2 (#149)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| CritPt | 1.1% | 0% |
| LMArena Hard Prompts | 1422 | 1426 |
| Epoch Capabilities Index | 143.04 | 142.48 |
| ARC-AGI-2 | 2.5% | — |
| SimpleBench | 41.2% | — |
| Kagi LLM Benchmark | 56.8% | — |
| ARC-AGI-1 | 33.3% | — |
| Chess Puzzles | — | 12% |
| EnigmaEval | 2.7% | — |
| DTBench | 76.5% | — |
| LMCA | 27.5% | — |
| ForecastBench | 60.6 | — |
Math Gemini 2.5 Flash leads
Gemini 2.5 Flash: 38.1 (#87), GPT-5.5 Instant: 26.1 (#241)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 73.1% | 68.1% |
| LMArena Math | 1415 | 1420 |
| FrontierMath (Tiers 1-3) | — | 26.3% |
| FrontierMath Tier 4 | — | 2.4% |
| Omni-MATH | 38.5% | — |
| FrontierMath (Feb 2025 set) | 4.8% | — |
| FrontierMath Tier 4 (v1) | 4.2% | — |
Knowledge GPT-5.5 Instant leads
Gemini 2.5 Flash: 36.1 (#162), GPT-5.5 Instant: 48.9 (#68)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| LMArena Expert | 1426 | 1409 |
| GPQA Diamond | — | 82.5% |
| Humanity's Last Exam | 12.1% | — |
| MMLU-Pro | 63.9% | — |
| Confabulations | 16.8% | — |
| Vectara Hallucination Rate | 7.8% | — |
| GPQA (HELM) | 39% | — |
Multimodal Gemini 2.5 Flash leads
Gemini 2.5 Flash: 41.2 (#31), GPT-5.5 Instant: 39.3 (#48)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| LMArena Vision | 1254 | 1250 |
| GeoBench | 76% | — |
| VPCT | 46.2% | — |
| LMArena Document | — | 1403 |
| SpatialViz-Bench | 36.9% | — |
Multilingual Too close to call
Gemini 2.5 Flash: 52.5 (#83), GPT-5.5 Instant: 53.0 (#76)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| LMArena Non-English | 1410 | 1417 |
| LMArena Chinese | 1450 | 1457 |
| LMArena French | 1433 | 1428 |
| LMArena German | 1419 | 1410 |
| LMArena Japanese | 1403 | 1408 |
| LMArena Korean | 1385 | 1393 |
| LMArena Russian | 1415 | 1430 |
| LMArena Spanish | 1421 | 1430 |
Instruction Following Gemini 2.5 Flash leads
Gemini 2.5 Flash: 75.9 (#50), GPT-5.5 Instant: 74.4 (#94)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| LMArena Instruction Following | 1405 | 1407 |
| IFEval | 89.8% | — |
Long Context Gemini 2.5 Flash leads
Gemini 2.5 Flash: 47.5 (#16), GPT-5.5 Instant: 43.4 (#92)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| LMArena Longer Query | 1419 | 1422 |
| Fiction.LiveBench | 77.8% | — |
Writing & Preference GPT-5.5 Instant leads
Gemini 2.5 Flash: 54.0 (#153), GPT-5.5 Instant: 62.0 (#81)
| Benchmark | Gemini 2.5 Flash | GPT-5.5 Instant |
|---|---|---|
| LMArena Text | 1417 | 1419 |
| LMArena Creative Writing | 1400 | 1420 |
| LMArena Multi-Turn | 1408 | 1434 |
| Short-Story Creative Writing | 76.5% | — |
| EQ-Bench Creative Writing | 1137 | — |
| WildBench | 81.7% | — |
Frequently asked questions
Is Gemini 2.5 Flash better than GPT-5.5 Instant?
GPT-5.5 Instant is the stronger model overall, scoring 42.5 to 39.0 on the Noometry Index.
Is Gemini 2.5 Flash or GPT-5.5 Instant better for coding?
GPT-5.5 Instant scores higher on coding benchmarks: 43.7 versus 35.5 in the Noometry coding category.
How many benchmarks do Gemini 2.5 Flash and GPT-5.5 Instant share?
21 benchmarks have published results for both models. Gemini 2.5 Flash has 54 scored results on Noometry and GPT-5.5 Instant has 27.