Model comparison
GPT-4.1 nano vs GPT-5.1
Head-to-head evidence from 18 shared benchmark results across 7 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-4.1 nano #161 (Estimated); GPT-5.1 #94 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-4.1 nano and GPT-5.1 share 18 comparable benchmark results. 1 of 8 categories are comparable. 3 results are unique to GPT-4.1 nano; 3 to GPT-5.1.
Updated July 24, 2026- Shared results
- 18
- GPT-4.1 nano only
- 3
- GPT-5.1 only
- 3
- Comparable categories
- 1 / 8
Pick GPT-5.1 if you want the stronger benchmark profile. GPT-4.1 nano 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 18 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 42.06. 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 1. The single biggest benchmark swing on the page is FrontierMath v2 (Tiers 1-3), 1.034% 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 $0.10 input / $0.40 output per 1M tokens for GPT-4.1 nano. That is roughly 25.0x on output cost alone. GPT-5.1 is the reasoning model in the pair, while GPT-4.1 nano 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-4.1 nano 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 | GPT-4.1 nano | Δ | GPT-5.1 |
|---|---|---|---|
| Math | GPT-4.1 nano1.0 | Margin→ 25.4 | GPT-5.126.4 |
| Knowledge | GPT-4.1 nano50.3 | MarginNo overlap | GPT-5.1Not measured |
| Inst. Following | GPT-4.1 nano83.2 | MarginNo overlap | GPT-5.1Not measured |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
FrontierMath v2 (Tiers 1-3)
MathA 1.034%B 31.034%Winner: GPT-5.1Δ 30FrontierMath v2 (Tiers 1-3): GPT-4.1 nano scored 1.034%; 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-4.1 nano | GPT-5.1 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-4.1 nano$0.1 input / $0.4 output | GPT-5.1$1.25 input / $10 output | GPT-4.1 nano has the lower combined listed price. |
| Generation speedtokens per second | GPT-4.1 nano181 tok/s | GPT-5.1111 tok/s | GPT-4.1 nano has the higher measured throughput. |
| First-answer latencyseconds to first token | GPT-4.1 nano0.63 s | GPT-5.157.47 s | GPT-4.1 nano reaches the first token sooner. |
| Context windowmaximum listed tokens | GPT-4.1 nano1M | GPT-5.1200K | GPT-4.1 nano lists the larger context window. |
Benchmark Deep Dive
Agentic5 benchmarks
Coding3 benchmarks
Reasoning2 benchmarks
Knowledge8 benchmarks
| Benchmark | GPT-4.1 nano | GPT-5.1 | Result |
|---|---|---|---|
| MMLUSource | 80.1% | — | Not comparable |
| GPQASource | 50.3% | — | Not comparable |
| Artificial Analysis Intelligence IndexSource | 9.6% | 36.9% | GPT-5.1 leads |
| AA-GPQA DiamondSource | 51.2% | 87.3% | GPT-5.1 leads |
| AA-HLESource | 3.9% | 26.5% | GPT-5.1 leads |
| AA-Omniscience IndexSource | -56.4% | 5.6% | GPT-5.1 leads |
| AA-Omniscience AccuracySource | 13.3% | 37.6% | GPT-5.1 leads |
| AA-Omniscience Hallucination RateSource | 80.4% | 51.3% | GPT-5.1 leads |
MathGPT-5.1 wins2 benchmarks
Multimodal2 benchmarks
Frequently Asked Questions (2)
Which is better, GPT-4.1 nano or GPT-5.1?
GPT-5.1 is ahead on BenchLM's BenchAlign leaderboard, 53.65 to 42.06. The biggest single separator in this matchup is FrontierMath v2 (Tiers 1-3), where the scores are 1.034% and 31.034%.
Which is better for math, GPT-4.1 nano or GPT-5.1?
GPT-5.1 has the edge for math in this comparison, averaging 26.4 versus 1. Inside this category, FrontierMath v2 (Tiers 1-3) is the benchmark that creates the most daylight between them.
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