Model comparison
GPT-5.5 Pro vs Mercury 2.5
GPT-5.5 Pro has enough public results to be ranked (#7); Mercury 2.5 does not yet, so treat this comparison as directional.
Last verified . 0 shared benchmarks.
Summary
- The widest gap is in math, where GPT-5.5 Pro leads 83.8 to 22.4.
- Mercury 2.5 is cheaper at $0.04 / $0.15 per million input/output tokens, against $30 / $180 for GPT-5.5 Pro.
- GPT-5.5 Pro accepts more context: 1.05M tokens versus 260K.
Side by side
| GPT-5.5 Pro | Mercury 2.5 | |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 64.3 | 30.2 |
| Released | 2026-04-23 | 2026-09-08 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 260K |
| Max output | 128K | 66K |
| Input $ / M tokens | $30 | $0.04 |
| Output $ / M tokens | $180 | $0.15 |
| Results tracked | 14 | 2 |
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Category by category
Coding Not comparable
GPT-5.5 Pro: —, Mercury 2.5: —
| Benchmark | GPT-5.5 Pro | Mercury 2.5 |
|---|---|---|
| ALE-Bench | — | 301.65 |
Reasoning Not comparable
GPT-5.5 Pro: 73.6 (#7), Mercury 2.5: —
| Benchmark | GPT-5.5 Pro | Mercury 2.5 |
|---|---|---|
| ARC-AGI-2 | 84.6% | — |
| SimpleBench | 76.9% | — |
| ARC-AGI-1 | 96.5% | — |
| CritPt | 30.6% | — |
| Chess Puzzles | 64% | — |
| DTBench | 96% | — |
| LMCA | 53.9% | — |
| Epoch Capabilities Index | 162.45 | — |
Math GPT-5.5 Pro leads
GPT-5.5 Pro: 83.8 (#8), Mercury 2.5: 22.4
| Benchmark | GPT-5.5 Pro | Mercury 2.5 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 87.7% | — |
| FrontierMath Tier 4 | 78% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | — | 3% |
| FrontierMath (Feb 2025 set) | 52.4% | — |
| FrontierMath Tier 4 (v1) | 39.6% | — |
Knowledge Not comparable
GPT-5.5 Pro: 64.2 (#17), Mercury 2.5: —
| Benchmark | GPT-5.5 Pro | Mercury 2.5 |
|---|---|---|
| GPQA Diamond | 93.9% | — |
Frequently asked questions
Is GPT-5.5 Pro better than Mercury 2.5?
GPT-5.5 Pro has enough public results to be ranked (#7); Mercury 2.5 does not yet, so treat this comparison as directional.
Which is cheaper, GPT-5.5 Pro 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-5.5 Pro lists at $30 and $180.
Which has the bigger context window?
GPT-5.5 Pro does, with 1.05M tokens against 260K.
How many benchmarks do GPT-5.5 Pro and Mercury 2.5 share?
0 benchmarks have published results for both models. GPT-5.5 Pro has 14 scored results on Noometry and Mercury 2.5 has 2.