Model comparison
GPT-5.4 nano vs Mercury 2.5
GPT-5.4 nano is the stronger model overall, scoring 41.9 to 33.5 on the Noometry Index. Mercury 2.5 costs 6.9× less per token, which makes it the better buy when GPT-5.4 nano's lead doesn't matter for your workload.
Last verified . 4 shared benchmarks.
Summary
- They share 4 benchmarks with published results for both. GPT-5.4 nano scores higher in 3 categories and Mercury 2.5 in 0 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in math, where GPT-5.4 nano leads 40.9 to 23.3.
- The biggest single-benchmark swing is CritPt: 9.3% for GPT-5.4 nano and 0% for Mercury 2.5.
- Mercury 2.5 is cheaper at $0.04 / $0.15 per million input/output tokens, against $0.20 / $1.25 for GPT-5.4 nano.
- GPT-5.4 nano accepts more context: 400K tokens versus 260K.
Side by side
| GPT-5.4 nano | Mercury 2.5 | |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 41.9 | 33.5 |
| Released | 2026-03-17 | 2026-09-08 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 260K |
| Max output | 128K | 66K |
| Input $ / M tokens | $0.20 | $0.04 |
| Output $ / M tokens | $1.25 | $0.15 |
| Results tracked | 40 | 4 |
Sponsored placements are available on pages like this one. Advertise on Noometry
Category by category
Coding GPT-5.4 nano leads
GPT-5.4 nano: 43.6 (#84), Mercury 2.5: 39.5 (#156)
| Benchmark | GPT-5.4 nano | Mercury 2.5 |
|---|---|---|
| SciCode | 46.9% | 38.5% |
| ALE-Bench | 1,005 | 301.65 |
| WeirdML | 49.2% | — |
| LMArena Coding | 1405 | — |
Reasoning GPT-5.4 nano leads
GPT-5.4 nano: 23.7 (#173), Mercury 2.5: 22.4 (#193)
| Benchmark | GPT-5.4 nano | Mercury 2.5 |
|---|---|---|
| CritPt | 9.3% | 0% |
| ARC-AGI-2 | 5.7% | — |
| Kagi LLM Benchmark | 39.7% | — |
| ARC-AGI-1 | 51.5% | — |
| Chess Puzzles | 30% | — |
| LMArena Hard Prompts | 1381 | — |
| Mystery Game Puzzles | 9% | — |
| DTBench | 80.3% | — |
| LMCA | 36.9% | — |
| Epoch Capabilities Index | 145.81 | — |
| ForecastBench | 57.3 | — |
Math GPT-5.4 nano leads
GPT-5.4 nano: 40.9 (#88), Mercury 2.5: 23.3 (#272)
| Benchmark | GPT-5.4 nano | Mercury 2.5 |
|---|---|---|
| ProofBench | 5% | 3% |
| FrontierMath (Tiers 1-3) | 44.9% | — |
| FrontierMath Tier 4 | 12.2% | — |
| OTIS Mock AIME 2024-2025 | 87.8% | — |
| LMArena Math | 1406 | — |
| FrontierMath (Feb 2025 set) | 25.9% | — |
| FrontierMath Tier 4 (v1) | 6.3% | — |
Knowledge Not comparable
GPT-5.4 nano: 41.9 (#103), Mercury 2.5: —
| Benchmark | GPT-5.4 nano | Mercury 2.5 |
|---|---|---|
| GPQA Diamond | 78.5% | — |
| SimpleQA Verified | 11.7% | — |
| Vectara Hallucination Rate | 3.1% | — |
| LMArena Expert | 1396 | — |
Multimodal Not comparable
GPT-5.4 nano: 36.7 (#78), Mercury 2.5: —
| Benchmark | GPT-5.4 nano | Mercury 2.5 |
|---|---|---|
| LMArena Vision | 1196 | — |
Multilingual Not comparable
GPT-5.4 nano: 48.6 (#140), Mercury 2.5: —
| Benchmark | GPT-5.4 nano | Mercury 2.5 |
|---|---|---|
| LMArena Non-English | 1359 | — |
| LMArena Chinese | 1392 | — |
| LMArena French | 1396 | — |
| LMArena German | 1367 | — |
| LMArena Japanese | 1343 | — |
| LMArena Korean | 1320 | — |
| LMArena Russian | 1363 | — |
| LMArena Spanish | 1371 | — |
Instruction Following Not comparable
GPT-5.4 nano: 71.9 (#144), Mercury 2.5: —
| Benchmark | GPT-5.4 nano | Mercury 2.5 |
|---|---|---|
| LMArena Instruction Following | 1362 | — |
Long Context Not comparable
GPT-5.4 nano: 41.6 (#137), Mercury 2.5: —
| Benchmark | GPT-5.4 nano | Mercury 2.5 |
|---|---|---|
| LMArena Longer Query | 1366 | — |
Writing & Preference Not comparable
GPT-5.4 nano: 55.7 (#142), Mercury 2.5: —
| Benchmark | GPT-5.4 nano | Mercury 2.5 |
|---|---|---|
| LMArena Text | 1372 | — |
| LMArena Creative Writing | 1314 | — |
| LMArena Multi-Turn | 1382 | — |
Frequently asked questions
Is GPT-5.4 nano better than Mercury 2.5?
GPT-5.4 nano is the stronger model overall, scoring 41.9 to 33.5 on the Noometry Index. Mercury 2.5 costs 6.9× less per token, which makes it the better buy when GPT-5.4 nano's lead doesn't matter for your workload.
Which is cheaper, GPT-5.4 nano or Mercury 2.5?
Mercury 2.5 is cheaper. It lists at $0.04 per million input tokens and $0.15 per million output tokens; GPT-5.4 nano lists at $0.20 and $1.25.
Is GPT-5.4 nano or Mercury 2.5 better for coding?
GPT-5.4 nano scores higher on coding benchmarks: 43.6 versus 39.5 in the Noometry coding category.
Which has the bigger context window?
GPT-5.4 nano does, with 400K tokens against 260K.
How many benchmarks do GPT-5.4 nano and Mercury 2.5 share?
4 benchmarks have published results for both models. GPT-5.4 nano has 40 scored results on Noometry and Mercury 2.5 has 4.