GPT-5 nano
GPT-5 nano is an API-only (closed weights) language model from OpenAI, released August 7, 2025. The context window is 391K tokens. On the Epoch Capabilities Index it scores 139.1, rank 128 of 256 rated models. API price: $0.05 input / $0.4 output per million tokens.
Check it against your own PC →
Lab
OpenAI
Released
August 7, 2025
Weights
API-only (closed weights)
Parameters
–
Context
391K
Price / M tokens
$0.05 / $0.4 in / out
Epoch ECI
139.1 #128
Strengths by category
ModelTape's 0–100 fit on Epoch AI benchmark results.
| Category | Score | Based on |
|---|---|---|
| Reasoning | 13.2 | Chess Puzzles, Mystery Game Puzzles |
| Math | 30.9 | ProofBench, MATH level 5, OTIS Mock AIME 2024-2025, FrontierMath-Tiers-1-3-v2-Private, FrontierMath-Tier-4-v2-Private |
| Knowledge | 49.8 | GPQA diamond, SimpleQA Verified |
Benchmark results
| Benchmark (Epoch AI) | Score |
|---|---|
| MATH level 5 | 95.2% |
| OTIS Mock AIME | 81.1% |
| GPQA Diamond | 61.7% |
| Terminal-Bench | 21.8% |
| FrontierMath (Tiers 1–3) | 21.1% |
| Chess Puzzles | 17.9% |
| ProofBench | 12.0% |
| SimpleQA Verified | 11.7% |
| FrontierMath-Tier-4-v2-Private | 2.4% |
| Mystery Game Puzzles | 0.0% |
Links
Announcement · Epoch AI benchmarks
Models with a similar score
Claude Opus 4 · Claude Haiku 4.5 · Qwen3-Max · Gemini 2.5 Flash (Sep 2025) · Claude Sonnet 4 · Gemma 4 26B A4B · Mistral Medium 3.5 · Gemini 2.5 Flash (May 2025)
More from OpenAI
GPT-6.1 Terra · GPT-6.1 Sol · GPT-6 Sol · GPT-6 Luna · GPT-6 Astra · GPT-5.6 Cyber · Daybreak Red · Daybreak Blue