Model comparison
GPT-5 Nano vs Mercury
Mercury is the stronger model overall, scoring 37.6 to 33.5 on the Noometry Index.
Last verified . 9 shared benchmarks.
Summary
- They share 9 benchmarks with published results for both. GPT-5 Nano scores higher in 2 categories and Mercury in 4 categories; 6 gaps are clear of the uncertainty.
- The widest gap is in instruction following, where GPT-5 Nano leads 75.0 to 65.2.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 62.2% for GPT-5 Nano and 21.6% for Mercury.
Side by side
| GPT-5 Nano | Mercury | |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 33.5 | 37.6 |
| Released | 2025-08-07 | — |
| Weights | Proprietary | Proprietary |
| Context window | 400K | — |
| Max output | 128K | — |
| Input $ / M tokens | $0.05 | — |
| Output $ / M tokens | $0.40 | — |
| Results tracked | 49 | 9 |
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Category by category
Coding Mercury leads
GPT-5 Nano: 33.6 (#254), Mercury: 38.7 (#170)
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| LMArena Coding | 1351 | 1322 |
| SWE-bench Verified (bash only) | 34.8% | — |
| WeirdML | 38.1% | — |
| ALE-Bench | 718.67 | — |
Agentic & Tool Use Not comparable
GPT-5 Nano: 25.8 (#106), Mercury: —
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| Terminal-Bench | 21.8% | — |
| Berkeley Function Calling Leaderboard | 51.5% | — |
Reasoning Mercury leads
GPT-5 Nano: 16.3 (#306), Mercury: 17.5 (#293)
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| Kagi LLM Benchmark | 62.2% | 21.6% |
| LMArena Hard Prompts | 1328 | 1285 |
| ARC-AGI-2 | 2.6% | — |
| ARC-AGI-1 | 20.7% | — |
| Chess Puzzles | 27% | — |
| Mystery Game Puzzles | 9% | — |
| DTBench | 62.7% | — |
| LMCA | 7.9% | — |
| Epoch Capabilities Index | 139.38 | — |
| ForecastBench | 59.1 | — |
Math Not comparable
GPT-5 Nano: 29.4 (#241), Mercury: —
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| FrontierMath (Tiers 1-3) | 20% | — |
| FrontierMath Tier 4 | 2.4% | — |
| OTIS Mock AIME 2024-2025 | 81.1% | — |
| ProofBench | 12% | — |
| Omni-MATH | 54.6% | — |
| LMArena Math | 1317 | — |
| MATH Level 5 | 95.2% | — |
| FrontierMath (Feb 2025 set) | 8.3% | — |
| FrontierMath Tier 4 (v1) | 2.1% | — |
Knowledge Not comparable
GPT-5 Nano: 35.9 (#178), Mercury: —
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| GPQA Diamond | 69.4% | — |
| SimpleQA Verified | 11.7% | — |
| MMLU-Pro | 77.8% | — |
| Vectara Hallucination Rate | 10.5% | — |
| GPQA (HELM) | 67.9% | — |
| LMArena Expert | 1321 | — |
Multimodal Not comparable
GPT-5 Nano: 31.3 (#108), Mercury: —
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| LMArena Vision | 1159 | — |
| VPCT | 37.2% | — |
Multilingual GPT-5 Nano leads
GPT-5 Nano: 45.3 (#172), Mercury: 41.6 (#206)
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| LMArena Non-English | 1313 | 1260 |
| LMArena Chinese | 1356 | — |
| LMArena German | 1327 | — |
| LMArena Japanese | 1226 | — |
| LMArena Korean | 1269 | — |
| LMArena Russian | 1296 | — |
| LMArena Spanish | 1360 | — |
Instruction Following GPT-5 Nano leads
GPT-5 Nano: 75.0 (#79), Mercury: 65.2 (#224)
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| LMArena Instruction Following | 1306 | 1239 |
| IFEval | 93.2% | — |
Long Context Mercury leads
GPT-5 Nano: 31.3 (#281), Mercury: 38.4 (#198)
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| LMArena Longer Query | 1312 | 1266 |
| Fiction.LiveBench | 44.4% | — |
Writing & Preference Mercury leads
GPT-5 Nano: 39.1 (#249), Mercury: 46.2 (#221)
| Benchmark | GPT-5 Nano | Mercury |
|---|---|---|
| LMArena Text | 1320 | 1282 |
| LMArena Creative Writing | 1249 | 1191 |
| LMArena Multi-Turn | 1311 | 1282 |
| EQ-Bench Creative Writing | 705 | — |
| WildBench | 80.6% | — |
Frequently asked questions
Is GPT-5 Nano better than Mercury?
Mercury is the stronger model overall, scoring 37.6 to 33.5 on the Noometry Index.
Is GPT-5 Nano or Mercury better for coding?
Mercury scores higher on coding benchmarks: 38.7 versus 33.6 in the Noometry coding category.
How many benchmarks do GPT-5 Nano and Mercury share?
9 benchmarks have published results for both models. GPT-5 Nano has 49 scored results on Noometry and Mercury has 9.