Model comparison
GPT-4o vs GPT-5.1
Head-to-head evidence from 13 shared benchmark results across 7 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-4o #165 (Supported); GPT-5.1 #94 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-4o and GPT-5.1 share 13 comparable benchmark results. 1 of 8 categories are comparable. 0 results are unique to GPT-4o; 8 to GPT-5.1.
Updated July 20, 2026- Shared results
- 13
- GPT-4o only
- 0
- GPT-5.1 only
- 8
- Comparable categories
- 1 / 8
Pick GPT-5.1 if you want the stronger benchmark profile. GPT-4o only becomes the better choice if you would rather avoid the extra latency and token burn of a reasoning model.
Confidence note. This is a partial-evidence comparison with 13 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 41.49. 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 0.3. The single biggest benchmark swing on the page is FrontierMath v2 (Tiers 1-3), 0.345% to 31.034%.
GPT-5.1 is the reasoning model in the pair, while GPT-4o 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. GPT-5.1 gives you the larger context window at 200K, compared with 128K for GPT-4o.
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 | GPT-4o | Δ | GPT-5.1 |
|---|---|---|---|
| Math | GPT-4o0.3 | Margin→ 26.1 | 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 0.345%B 31.034%Winner: GPT-5.1Δ 30.7FrontierMath v2 (Tiers 1-3): GPT-4o scored 0.345%; GPT-5.1 scored 31.034%. GPT-5.1 wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-4o | GPT-5.1 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-4o$2.5 input / $10 output | GPT-5.1$1.25 input / $10 output | GPT-5.1 has the lower combined listed price. |
| Generation speedtokens per second | GPT-4o131 tok/s | GPT-5.1111 tok/s | GPT-4o has the higher measured throughput. |
| First-answer latencyseconds to first token | GPT-4o0.81 s | GPT-5.157.47 s | GPT-4o reaches the first token sooner. |
| Context windowmaximum listed tokens | GPT-4o128K | GPT-5.1200K | GPT-5.1 lists the larger context window. |
Benchmark Deep Dive
Agentic5 benchmarks
Coding3 benchmarks
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | GPT-4o | GPT-5.1 | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 11.2% | 36.9% | GPT-5.1 leads |
| AA-GPQA DiamondSource | 54.3% | 87.3% | GPT-5.1 leads |
| AA-HLESource | 3.3% | 26.5% | GPT-5.1 leads |
| AA-Omniscience IndexSource | -10.7% | 5.6% | GPT-5.1 leads |
| AA-Omniscience AccuracySource | 19.7% | 37.6% | GPT-5.1 leads |
| AA-Omniscience Hallucination RateSource | 37.9% | 51.3% | GPT-4o leads |
MathGPT-5.1 wins2 benchmarks
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | GPT-4o | GPT-5.1 | Result |
|---|---|---|---|
| AA-IFBenchSource | 34.3% | 72.9% | GPT-5.1 leads |
Frequently Asked Questions (2)
Which is better, GPT-4o or GPT-5.1?
GPT-5.1 is ahead on BenchLM's BenchAlign leaderboard, 53.65 to 41.49. The biggest single separator in this matchup is FrontierMath v2 (Tiers 1-3), where the scores are 0.345% and 31.034%.
Which is better for math, GPT-4o or GPT-5.1?
GPT-5.1 has the edge for math in this comparison, averaging 26.4 versus 0.3. Inside this category, FrontierMath v2 (Tiers 1-3) is the benchmark that creates the most daylight between them.
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