Model comparison
Gemini 2.5 Flash vs GPT-5.1
Head-to-head evidence from 15 shared benchmark results across 7 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Gemini 2.5 Flash #130 (Supported); GPT-5.1 #94 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Gemini 2.5 Flash and GPT-5.1 share 15 comparable benchmark results. 1 of 8 categories are comparable. 0 results are unique to Gemini 2.5 Flash; 6 to GPT-5.1.
Updated July 20, 2026- Shared results
- 15
- Gemini 2.5 Flash only
- 0
- GPT-5.1 only
- 6
- Comparable categories
- 1 / 8
Pick GPT-5.1 if you want the stronger benchmark profile. Gemini 2.5 Flash only becomes the better choice if you want the cheaper token bill or you need the larger 1M context window.
Confidence note. This is a partial-evidence comparison with 15 shared benchmark results across 7 evidence categories; 1 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
GPT-5.1 is clearly ahead on the BenchAlign aggregate, 53.65 to 48.09. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.1's sharpest advantage is in mathematics, where it averages 26.4 against 4.7. The single biggest benchmark swing on the page is FrontierMath v2 (Tiers 1-3), 4.844% to 31.034%.
GPT-5.1 is also the more expensive model on tokens at $1.25 input / $10.00 output per 1M tokens, versus $0.30 input / $2.50 output per 1M tokens for Gemini 2.5 Flash. That is roughly 4.0x on output cost alone. GPT-5.1 is the reasoning model in the pair, while Gemini 2.5 Flash is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. Gemini 2.5 Flash gives you the larger context window at 1M, compared with 200K for GPT-5.1.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | Gemini 2.5 Flash | Δ | GPT-5.1 |
|---|---|---|---|
| Math | Gemini 2.5 Flash4.7 | Margin→ 21.7 | GPT-5.126.4 |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
FrontierMath v2 (Tiers 1-3)
MathA 4.844%B 31.034%Winner: GPT-5.1Δ 26.2FrontierMath v2 (Tiers 1-3): Gemini 2.5 Flash scored 4.844%; GPT-5.1 scored 31.034%. GPT-5.1 wins this benchmark. - Source ↗
FrontierMath v2 (Tier 4)
MathA 4.167%B 12.500%Winner: GPT-5.1Δ 8.3FrontierMath v2 (Tier 4): Gemini 2.5 Flash scored 4.167%; GPT-5.1 scored 12.500%. GPT-5.1 wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Gemini 2.5 Flash | GPT-5.1 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Gemini 2.5 Flash$0.3 input / $2.5 output | GPT-5.1$1.25 input / $10 output | Gemini 2.5 Flash has the lower combined listed price. |
| Generation speedtokens per second | Gemini 2.5 Flash221 tok/s | GPT-5.1111 tok/s | Gemini 2.5 Flash has the higher measured throughput. |
| First-answer latencyseconds to first token | Gemini 2.5 Flash0.50 s | GPT-5.157.47 s | Gemini 2.5 Flash reaches the first token sooner. |
| Context windowmaximum listed tokens | Gemini 2.5 Flash1M | GPT-5.1200K | Gemini 2.5 Flash lists the larger context window. |
Benchmark Deep Dive
Agentic5 benchmarks
Coding3 benchmarks
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | Gemini 2.5 Flash | GPT-5.1 | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 14.1% | 36.9% | GPT-5.1 leads |
| AA-GPQA DiamondSource | 68.3% | 87.3% | GPT-5.1 leads |
| AA-HLESource | 5.1% | 26.5% | GPT-5.1 leads |
| AA-Omniscience IndexSource | -42.0% | 5.6% | GPT-5.1 leads |
| AA-Omniscience AccuracySource | 26.5% | 37.6% | GPT-5.1 leads |
| AA-Omniscience Hallucination RateSource | 93.3% | 51.3% | GPT-5.1 leads |
MathGPT-5.1 wins2 benchmarks
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | Gemini 2.5 Flash | GPT-5.1 | Result |
|---|---|---|---|
| AA-IFBenchSource | 39.0% | 72.9% | GPT-5.1 leads |
Frequently Asked Questions (2)
Which is better, Gemini 2.5 Flash or GPT-5.1?
GPT-5.1 is ahead on BenchLM's BenchAlign leaderboard, 53.65 to 48.09. The biggest single separator in this matchup is FrontierMath v2 (Tiers 1-3), where the scores are 4.844% and 31.034%.
Which is better for math, Gemini 2.5 Flash or GPT-5.1?
GPT-5.1 has the edge for math in this comparison, averaging 26.4 versus 4.7. Inside this category, FrontierMath v2 (Tiers 1-3) is the benchmark that creates the most daylight between them.
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