Model comparison
GPT-5.3 Chat vs Mercury
GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 37.6 on the Noometry Index.
Last verified . 8 shared benchmarks.
Summary
- They share 8 benchmarks with published results for both. GPT-5.3 Chat 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-5.3 Chat leads 63.1 to 46.2.
Side by side
| GPT-5.3 Chat | Mercury | |
|---|---|---|
| Provider | OpenAI | Inception |
| Noometry Index | 42.8 | 37.6 |
| Released | 2026-03-03 | — |
| Weights | Proprietary | Proprietary |
| Context window | 128K | — |
| Max output | 16K | — |
| Input $ / M tokens | $1.75 | — |
| Output $ / M tokens | $14 | — |
| Results tracked | 18 | 9 |
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Category by category
Coding GPT-5.3 Chat leads
GPT-5.3 Chat: 41.4 (#124), Mercury: 38.7 (#170)
| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Coding | 1408 | 1322 |
Reasoning GPT-5.3 Chat leads
GPT-5.3 Chat: 28.5 (#102), Mercury: 17.5 (#293)
| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Hard Prompts | 1399 | 1285 |
| Kagi LLM Benchmark | — | 21.6% |
Math Not comparable
GPT-5.3 Chat: 38.2 (#142), Mercury: —
| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Math | 1389 | — |
Knowledge Not comparable
GPT-5.3 Chat: 38.8 (#140), Mercury: —
| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Expert | 1397 | — |
Multilingual GPT-5.3 Chat leads
GPT-5.3 Chat: 50.3 (#124), Mercury: 41.6 (#206)
| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Non-English | 1382 | 1260 |
| LMArena Chinese | 1432 | — |
| LMArena French | 1397 | — |
| LMArena German | 1384 | — |
| LMArena Japanese | 1352 | — |
| LMArena Korean | 1346 | — |
| LMArena Russian | 1400 | — |
| LMArena Spanish | 1371 | — |
Instruction Following GPT-5.3 Chat leads
GPT-5.3 Chat: 72.8 (#129), Mercury: 65.2 (#224)
| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Instruction Following | 1378 | 1239 |
Long Context GPT-5.3 Chat leads
GPT-5.3 Chat: 42.6 (#120), Mercury: 38.4 (#198)
| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Longer Query | 1396 | 1266 |
Writing & Preference GPT-5.3 Chat leads
GPT-5.3 Chat: 63.1 (#68), Mercury: 46.2 (#221)
| Benchmark | GPT-5.3 Chat | Mercury |
|---|---|---|
| LMArena Text | 1389 | 1282 |
| LMArena Creative Writing | 1355 | 1191 |
| LMArena Multi-Turn | 1412 | 1282 |
| EQ-Bench Creative Writing | 1690 | — |
Frequently asked questions
Is GPT-5.3 Chat better than Mercury?
GPT-5.3 Chat is the stronger model overall, scoring 42.8 to 37.6 on the Noometry Index.
Is GPT-5.3 Chat or Mercury better for coding?
GPT-5.3 Chat scores higher on coding benchmarks: 41.4 versus 38.7 in the Noometry coding category.
How many benchmarks do GPT-5.3 Chat and Mercury share?
8 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Mercury has 9.