Model comparison
GPT-5.5 Instant vs Mercury
GPT-5.5 Instant is the stronger model overall, scoring 42.5 to 37.3 on the Noometry Index.
Last verified . 8 shared benchmarks.
Summary
- They share 8 benchmarks with published results for both. GPT-5.5 Instant scores higher in 6 categories and Mercury in 0 categories; 6 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where GPT-5.5 Instant leads 62.0 to 46.2.
Side by side
| GPT-5.5 Instant | Mercury | |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 42.5 | 37.3 |
| Released | 2026-05-05 | — |
| Weights | Proprietary | Proprietary |
| Context window | — | — |
| Max output | — | — |
| Input $ / M tokens | — | — |
| Output $ / M tokens | — | — |
| Results tracked | 27 | 9 |
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Category by category
Coding GPT-5.5 Instant leads
GPT-5.5 Instant: 43.7 (#73), Mercury: 38.1 (#164)
| Benchmark | GPT-5.5 Instant | Mercury |
|---|---|---|
| LMArena Coding | 1433 | 1323 |
| SciCode | 48.6% | — |
Reasoning GPT-5.5 Instant leads
GPT-5.5 Instant: 24.2 (#149), Mercury: 16.8 (#288)
| Benchmark | GPT-5.5 Instant | Mercury |
|---|---|---|
| LMArena Hard Prompts | 1426 | 1284 |
| Kagi LLM Benchmark | — | 21.6% |
| CritPt | 0% | — |
| Chess Puzzles | 12% | — |
| Epoch Capabilities Index | 142.48 | — |
Math Not comparable
GPT-5.5 Instant: 26.1 (#241), Mercury: —
| Benchmark | GPT-5.5 Instant | Mercury |
|---|---|---|
| FrontierMath (Tiers 1-3) | 26.3% | — |
| FrontierMath Tier 4 | 2.4% | — |
| OTIS Mock AIME 2024-2025 | 68.1% | — |
| LMArena Math | 1420 | — |
Knowledge Not comparable
GPT-5.5 Instant: 48.9 (#68), Mercury: —
| Benchmark | GPT-5.5 Instant | Mercury |
|---|---|---|
| GPQA Diamond | 82.5% | — |
| LMArena Expert | 1409 | — |
Multimodal Not comparable
GPT-5.5 Instant: 39.3 (#48), Mercury: —
| Benchmark | GPT-5.5 Instant | Mercury |
|---|---|---|
| LMArena Vision | 1250 | — |
| LMArena Document | 1403 | — |
Multilingual GPT-5.5 Instant leads
GPT-5.5 Instant: 53.0 (#76), Mercury: 41.7 (#201)
| Benchmark | GPT-5.5 Instant | Mercury |
|---|---|---|
| LMArena Non-English | 1417 | 1259 |
| LMArena Chinese | 1457 | — |
| LMArena French | 1428 | — |
| LMArena German | 1410 | — |
| LMArena Japanese | 1408 | — |
| LMArena Korean | 1393 | — |
| LMArena Russian | 1430 | — |
| LMArena Spanish | 1430 | — |
Instruction Following GPT-5.5 Instant leads
GPT-5.5 Instant: 74.4 (#94), Mercury: 65.3 (#220)
| Benchmark | GPT-5.5 Instant | Mercury |
|---|---|---|
| LMArena Instruction Following | 1407 | 1238 |
Long Context GPT-5.5 Instant leads
GPT-5.5 Instant: 43.4 (#92), Mercury: 38.3 (#193)
| Benchmark | GPT-5.5 Instant | Mercury |
|---|---|---|
| LMArena Longer Query | 1422 | 1264 |
Writing & Preference GPT-5.5 Instant leads
GPT-5.5 Instant: 62.0 (#81), Mercury: 46.2 (#216)
| Benchmark | GPT-5.5 Instant | Mercury |
|---|---|---|
| LMArena Text | 1419 | 1282 |
| LMArena Creative Writing | 1420 | 1186 |
| LMArena Multi-Turn | 1434 | 1283 |
Frequently asked questions
Is GPT-5.5 Instant better than Mercury?
GPT-5.5 Instant is the stronger model overall, scoring 42.5 to 37.3 on the Noometry Index.
Is GPT-5.5 Instant or Mercury better for coding?
GPT-5.5 Instant scores higher on coding benchmarks: 43.7 versus 38.1 in the Noometry coding category.
How many benchmarks do GPT-5.5 Instant and Mercury share?
8 benchmarks have published results for both models. GPT-5.5 Instant has 27 scored results on Noometry and Mercury has 9.