Model comparison
GPT-5.4 Pro vs Mercury 2
GPT-5.4 Pro is the stronger model overall, scoring 58.9 to 39.1 on the Noometry Index. Mercury 2 costs 180× less per token, which makes it the better buy when GPT-5.4 Pro's lead doesn't matter for your workload.
Last verified . 3 shared benchmarks.
Summary
- They share 3 benchmarks with published results for both. GPT-5.4 Pro scores higher in 3 categories and Mercury 2 in 0 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5.4 Pro leads 70.7 to 23.8.
- The biggest single-benchmark swing is CritPt: 30% for GPT-5.4 Pro and 0.8% for Mercury 2.
- Mercury 2 is cheaper at $0.25 / $0.75 per million input/output tokens, against $30 / $180 for GPT-5.4 Pro.
- GPT-5.4 Pro accepts more context: 1.05M tokens versus 128K.
Side by side
| GPT-5.4 Pro | Mercury 2 | |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 58.9 | 39.1 |
| Released | 2026-03-05 | 2026-02-20 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 128K |
| Max output | 128K | 50K |
| Input $ / M tokens | $30 | $0.25 |
| Output $ / M tokens | $180 | $0.75 |
| Results tracked | 16 | 17 |
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Category by category
Coding GPT-5.4 Pro leads
GPT-5.4 Pro: 43.2 (#90), Mercury 2: 33.5 (#255)
| Benchmark | GPT-5.4 Pro | Mercury 2 |
|---|---|---|
| WeirdML | 57.4% | 43.2% |
| LMArena WebDev | — | 1171 |
| SciCode | — | 38.7% |
| LMArena Coding | — | 1391 |
| ALE-Bench | — | 785.58 |
Reasoning GPT-5.4 Pro leads
GPT-5.4 Pro: 70.7 (#13), Mercury 2: 23.8 (#170)
| Benchmark | GPT-5.4 Pro | Mercury 2 |
|---|---|---|
| CritPt | 30% | 0.8% |
| ARC-AGI-2 | 83.3% | — |
| SimpleBench | 74.1% | — |
| ARC-AGI-1 | 94.5% | — |
| Chess Puzzles | 58.6% | — |
| EnigmaEval | 23.8% | — |
| LMArena Hard Prompts | — | 1362 |
| Epoch Capabilities Index | 158.93 | — |
Math Not comparable
GPT-5.4 Pro: 72.4 (#22), Mercury 2: —
| Benchmark | GPT-5.4 Pro | Mercury 2 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 82.5% | — |
| FrontierMath Tier 4 | 58.5% | — |
| FrontierMath (Feb 2025 set) | 50% | — |
| FrontierMath Tier 4 (v1) | 37.5% | — |
Knowledge GPT-5.4 Pro leads
GPT-5.4 Pro: 68.3 (#7), Mercury 2: 36.2 (#172)
| Benchmark | GPT-5.4 Pro | Mercury 2 |
|---|---|---|
| Vectara Hallucination Rate | 8.3% | 12.3% |
| GPQA Diamond | 94.6% | — |
| Humanity's Last Exam | 44.3% | — |
| SimpleQA Verified | 46.3% | — |
| LMArena Expert | — | 1358 |
Multilingual Not comparable
GPT-5.4 Pro: —, Mercury 2: 46.6 (#157)
| Benchmark | GPT-5.4 Pro | Mercury 2 |
|---|---|---|
| LMArena Non-English | — | 1331 |
| LMArena Chinese | — | 1417 |
| LMArena Russian | — | 1304 |
Instruction Following Not comparable
GPT-5.4 Pro: —, Mercury 2: 70.2 (#165)
| Benchmark | GPT-5.4 Pro | Mercury 2 |
|---|---|---|
| LMArena Instruction Following | — | 1329 |
Long Context Not comparable
GPT-5.4 Pro: —, Mercury 2: 40.5 (#154)
| Benchmark | GPT-5.4 Pro | Mercury 2 |
|---|---|---|
| LMArena Longer Query | — | 1330 |
Writing & Preference Not comparable
GPT-5.4 Pro: —, Mercury 2: 53.8 (#155)
| Benchmark | GPT-5.4 Pro | Mercury 2 |
|---|---|---|
| LMArena Text | — | 1355 |
| LMArena Creative Writing | — | 1289 |
| LMArena Multi-Turn | — | 1358 |
Frequently asked questions
Is GPT-5.4 Pro better than Mercury 2?
GPT-5.4 Pro is the stronger model overall, scoring 58.9 to 39.1 on the Noometry Index. Mercury 2 costs 180× less per token, which makes it the better buy when GPT-5.4 Pro's lead doesn't matter for your workload.
Which is cheaper, GPT-5.4 Pro or Mercury 2?
Mercury 2 is cheaper. It lists at $0.25 per million input tokens and $0.75 per million output tokens; GPT-5.4 Pro lists at $30 and $180.
Is GPT-5.4 Pro or Mercury 2 better for coding?
GPT-5.4 Pro scores higher on coding benchmarks: 43.2 versus 33.5 in the Noometry coding category.
Which has the bigger context window?
GPT-5.4 Pro does, with 1.05M tokens against 128K.
How many benchmarks do GPT-5.4 Pro and Mercury 2 share?
3 benchmarks have published results for both models. GPT-5.4 Pro has 16 scored results on Noometry and Mercury 2 has 17.