Model comparison
GPT-5.3 Chat vs GPT-6 Luna
GPT-6 Luna is the stronger model overall, scoring 45.1 to 42.1 on the Noometry Index.
Last verified . 13 shared benchmarks.
Summary
- They share 13 benchmarks with published results for both. GPT-5.3 Chat scores higher in 1 category and GPT-6 Luna in 7 categories; 5 gaps are clear of the uncertainty.
- The widest gap is in coding, where GPT-6 Luna leads 54.7 to 40.8.
- GPT-6 Luna is cheaper at $0.10 / $0.50 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.
- GPT-6 Luna accepts more context: 1.05M tokens versus 128K.
Side by side
| GPT-5.3 Chat | GPT-6 Luna | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 42.1 | 45.1 |
| Released | 2026-03-03 | 2026-09-22 |
| Weights | Proprietary | Proprietary |
| Context window | 128K | 1.05M |
| Max output | 16K | 128K |
| Input $ / M tokens | $1.75 | $0.10 |
| Output $ / M tokens | $14 | $0.50 |
| Results tracked | 18 | 18 |
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Category by category
Coding GPT-6 Luna leads
GPT-5.3 Chat: 40.8 (#124), GPT-6 Luna: 54.7 (#24)
| Benchmark | GPT-5.3 Chat | GPT-6 Luna |
|---|---|---|
| LMArena Coding | 1408 | 1448 |
| DeepSWE | — | 66.6% |
| FrontierCode | — | 42.4% |
| LMArena WebDev | — | 1583 |
Reasoning GPT-6 Luna leads
GPT-5.3 Chat: 27.3 (#105), GPT-6 Luna: 31.7 (#68)
| Benchmark | GPT-5.3 Chat | GPT-6 Luna |
|---|---|---|
| LMArena Hard Prompts | 1399 | 1415 |
| NYT Connections (extended) | — | 68.7% |
Math Too close to call
GPT-5.3 Chat: 35.4 (#146), GPT-6 Luna: 35.6 (#140)
| Benchmark | GPT-5.3 Chat | GPT-6 Luna |
|---|---|---|
| LMArena Math | 1389 | 1396 |
Knowledge GPT-6 Luna leads
GPT-5.3 Chat: 38.2 (#137), GPT-6 Luna: 40.1 (#110)
| Benchmark | GPT-5.3 Chat | GPT-6 Luna |
|---|---|---|
| LMArena Expert | 1397 | 1458 |
Multimodal Not comparable
GPT-5.3 Chat: —, GPT-6 Luna: 42.0 (#27)
| Benchmark | GPT-5.3 Chat | GPT-6 Luna |
|---|---|---|
| Furniture Assembly | — | 44.2% |
Multilingual Too close to call
GPT-5.3 Chat: 50.5 (#119), GPT-6 Luna: 51.0 (#111)
| Benchmark | GPT-5.3 Chat | GPT-6 Luna |
|---|---|---|
| LMArena Non-English | 1383 | 1390 |
| LMArena Chinese | 1433 | 1425 |
| LMArena Russian | 1400 | 1392 |
| LMArena Spanish | 1371 | 1416 |
| LMArena French | 1398 | — |
| LMArena German | 1384 | — |
| LMArena Japanese | 1351 | — |
| LMArena Korean | 1347 | — |
Instruction Following GPT-6 Luna leads
GPT-5.3 Chat: 73.0 (#124), GPT-6 Luna: 74.7 (#85)
| Benchmark | GPT-5.3 Chat | GPT-6 Luna |
|---|---|---|
| LMArena Instruction Following | 1378 | 1414 |
Long Context Too close to call
GPT-5.3 Chat: 42.6 (#115), GPT-6 Luna: 43.3 (#95)
| Benchmark | GPT-5.3 Chat | GPT-6 Luna |
|---|---|---|
| LMArena Longer Query | 1396 | 1417 |
Writing & Preference GPT-5.3 Chat leads
GPT-5.3 Chat: 63.3 (#65), GPT-6 Luna: 58.4 (#115)
| Benchmark | GPT-5.3 Chat | GPT-6 Luna |
|---|---|---|
| LMArena Text | 1389 | 1392 |
| LMArena Creative Writing | 1356 | 1357 |
| LMArena Multi-Turn | 1413 | 1400 |
| EQ-Bench Creative Writing | 1690 | — |
Frequently asked questions
Is GPT-5.3 Chat better than GPT-6 Luna?
GPT-6 Luna is the stronger model overall, scoring 45.1 to 42.1 on the Noometry Index.
Which is cheaper, GPT-5.3 Chat or GPT-6 Luna?
GPT-6 Luna is cheaper. It lists at $0.10 per million input tokens and $0.50 per million output tokens; GPT-5.3 Chat lists at $1.75 and $14.
Is GPT-5.3 Chat or GPT-6 Luna better for coding?
GPT-6 Luna scores higher on coding benchmarks: 54.7 versus 40.8 in the Noometry coding category.
Which has the bigger context window?
GPT-6 Luna does, with 1.05M tokens against 128K.
How many benchmarks do GPT-5.3 Chat and GPT-6 Luna share?
13 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and GPT-6 Luna has 18.