Model comparison
GPT-5.3 Chat vs o3-pro
GPT-5.3 Chat and o3-pro score almost the same on the Noometry Index (42.8 vs 42.9), so choose on price, context window or the category you care about most.
Last verified . 0 shared benchmarks.
Summary
- The widest gap is in long context, where o3-pro leads 72.2 to 42.6.
- GPT-5.3 Chat is cheaper at $1.75 / $14 per million input/output tokens, against $20 / $80 for o3-pro.
- o3-pro accepts more context: 200K tokens versus 128K.
Side by side
| GPT-5.3 Chat | o3-pro | |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Noometry Index | 42.8 | 42.9 |
| Released | 2026-03-03 | 2025-06-10 |
| Weights | Proprietary | Proprietary |
| Context window | 128K | 200K |
| Max output | 16K | 100K |
| Input $ / M tokens | $1.75 | $20 |
| Output $ / M tokens | $14 | $80 |
| Results tracked | 18 | 12 |
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Category by category
Coding o3-pro leads
GPT-5.3 Chat: 41.4 (#124), o3-pro: 55.5 (#24)
| Benchmark | GPT-5.3 Chat | o3-pro |
|---|---|---|
| Aider Polyglot | — | 84.9% |
| WeirdML | — | 58.2% |
| LMArena Coding | 1408 | — |
Reasoning GPT-5.3 Chat leads
GPT-5.3 Chat: 28.5 (#102), o3-pro: 23.8 (#171)
| Benchmark | GPT-5.3 Chat | o3-pro |
|---|---|---|
| ARC-AGI-2 | — | 4.9% |
| Kagi LLM Benchmark | — | 72.1% |
| ARC-AGI-1 | — | 59.3% |
| LMArena Hard Prompts | 1399 | — |
| DTBench | — | 86.9% |
| LMCA | — | 38.5% |
| Epoch Capabilities Index | — | 147.42 |
Math Not comparable
GPT-5.3 Chat: 38.2 (#142), o3-pro: —
| Benchmark | GPT-5.3 Chat | o3-pro |
|---|---|---|
| LMArena Math | 1389 | — |
Knowledge GPT-5.3 Chat leads
GPT-5.3 Chat: 38.8 (#140), o3-pro: 29.5 (#238)
| Benchmark | GPT-5.3 Chat | o3-pro |
|---|---|---|
| Confabulations | — | 14.2% |
| Vectara Hallucination Rate | — | 23.3% |
| LMArena Expert | 1397 | — |
Multilingual Not comparable
GPT-5.3 Chat: 50.3 (#124), o3-pro: —
| Benchmark | GPT-5.3 Chat | o3-pro |
|---|---|---|
| LMArena Non-English | 1382 | — |
| LMArena Chinese | 1432 | — |
| LMArena French | 1397 | — |
| LMArena German | 1384 | — |
| LMArena Japanese | 1352 | — |
| LMArena Korean | 1346 | — |
| LMArena Russian | 1400 | — |
| LMArena Spanish | 1371 | — |
Instruction Following Not comparable
GPT-5.3 Chat: 72.8 (#129), o3-pro: —
| Benchmark | GPT-5.3 Chat | o3-pro |
|---|---|---|
| LMArena Instruction Following | 1378 | — |
Long Context o3-pro leads
GPT-5.3 Chat: 42.6 (#120), o3-pro: 72.2 (#1)
| Benchmark | GPT-5.3 Chat | o3-pro |
|---|---|---|
| Fiction.LiveBench | — | 97.2% |
| LMArena Longer Query | 1396 | — |
Writing & Preference GPT-5.3 Chat leads
GPT-5.3 Chat: 63.1 (#68), o3-pro: 57.1 (#133)
| Benchmark | GPT-5.3 Chat | o3-pro |
|---|---|---|
| LMArena Text | 1389 | — |
| LMArena Creative Writing | 1355 | — |
| Short-Story Creative Writing | — | 84.4% |
| EQ-Bench Creative Writing | 1690 | — |
| LMArena Multi-Turn | 1412 | — |
Frequently asked questions
Is GPT-5.3 Chat better than o3-pro?
GPT-5.3 Chat and o3-pro score almost the same on the Noometry Index (42.8 vs 42.9), so choose on price, context window or the category you care about most.
Which is cheaper, GPT-5.3 Chat or o3-pro?
GPT-5.3 Chat is cheaper. It lists at $1.75 per million input tokens and $14 per million output tokens; o3-pro lists at $20 and $80.
Is GPT-5.3 Chat or o3-pro better for coding?
o3-pro scores higher on coding benchmarks: 55.5 versus 41.4 in the Noometry coding category.
Which has the bigger context window?
o3-pro does, with 200K tokens against 128K.
How many benchmarks do GPT-5.3 Chat and o3-pro share?
0 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and o3-pro has 12.