Claude Opus 4.5 vs GPT-5.3 Codex vs GPT-5.1
GPT-5.3 Codex comes out ahead, 64 to 60 and 55 on our weighted score, though GPT-5.1 is 29% cheaper per token.
AnthropicClaude Opus 4.5
55/100- ECI150.1
- Price$5.00 / $25.00
- Context200K
- Our pick
OpenAIGPT-5.3 Codex
64/100- ECI156.8
- Price$1.75 / $14.00
- Context400K
- OpenAI
GPT-5.1
60/100- ECI149.7
- Price$1.25 / $10.00
- Context400K
GPT-5.3 Codex is our pick
GPT-5.3 Codex is the better all-round choice, scoring 64/100 against GPT-5.1 (60) and Claude Opus 4.5 (55). It leads on capability. GPT-5.1 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-5.3 CodexCapabilities Index (ECI): GPT-5.3 Codex 156.8 · Claude Opus 4.5 150.1 · GPT-5.1 149.7
- Lowest priceGPT-5.1GPT-5.1 $3.44 · GPT-5.3 Codex $4.81 · Claude Opus 4.5 $10.00 per 1M tokens (3:1 blend)
- Longest contextGPT-5.3 Codex and GPT-5.1GPT-5.3 Codex 400,000 · GPT-5.1 400,000 · Claude Opus 4.5 200,000 tokens
- Widest inputsClaude Opus 4.5 and GPT-5.3 CodexClaude Opus 4.5: Text, Images, PDFs · GPT-5.3 Codex: Text, Images, PDFs · GPT-5.1: Text, Images
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Claude Opus 4.5 | GPT-5.3 Codex | GPT-5.1 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 78 | 87 | 78 |
| Price | 25% | 2 | 18 | 24 |
| Inputs & features | 15% | 80 | 80 | 70 |
| Context window | 10% | 32 | 44 | 44 |
| Overall | 100% | 55/100 | 64/100 | 60/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Opus 4.5Anthropic | GPT-5.3 CodexOpenAI | GPT-5.1OpenAI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 150.1 | 156.8 (best) | 149.7 |
| ECI rank | #48 of 148 | #18 of 148 (best) | #52 of 148 |
| GPQA DiamondGraduate-level science questions | 86.1% | — | 87.6% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 34.4% | — | — |
| OTIS Mock AIME 2024–2025Competition mathematics | 86.1% | — | 88.6% (best) |
| SWE-bench VerifiedFixing real GitHub issues | 76.7% (best) | 74.8% | 68.0% |
| SimpleQA VerifiedShort factual questions | 45.7% | — | 48.0% (best) |
| Price per million tokens | |||
| Input | $5.00 | $1.75 | $1.25 (best) |
| Output | $25.00 | $14.00 | $10.00 (best) |
| Cached input | $0.50 | $0.175 | $0.125 (best) |
| Blended (3:1) | $10.00 | $4.81 | $3.44 (best) |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official Anthropic API | Official OpenAI API | Official OpenAI API |
| Limits | |||
| Context window | 200,000 tokens | 400,000 tokens (best) | 400,000 tokens (best) |
| Max output | 64,000 tokens | 128,000 tokens (best) | 128,000 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | No |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high | Yeslow · medium · high · xhigh | Yeslow · medium · high |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | claude-opus-4-5 | gpt-5.3-codex | gpt-5.1 |
| API providers | 28 (best) | 19 | 21 |
| Released | Nov 24, 2025 | Feb 5, 2026 | Nov 13, 2025 |
| Knowledge cutoff | May 2025 | Aug 31, 2025 | Sep 30, 2024 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Claude Opus 4.5$100.00
- GPT-5.3 Codex$45.50
- GPT-5.1$32.50
Which should you choose?
Which is better: Claude Opus 4.5, GPT-5.3 Codex or GPT-5.1?
GPT-5.3 Codex is the better all-round choice, scoring 64/100 against GPT-5.1 (60) and Claude Opus 4.5 (55). It leads on capability. GPT-5.1 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Claude Opus 4.5, GPT-5.3 Codex or GPT-5.1?
GPT-5.1 is cheaper at $1.25 input / $10.00 output per million tokens (official OpenAI API price). GPT-5.3 Codex costs $1.75 input / $14.00 output per million tokens (official OpenAI API price); Claude Opus 4.5 costs $5.00 input / $25.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $3.44 per million tokens for GPT-5.1 versus $4.81 for GPT-5.3 Codex (1.4× as much) and $10.00 for Claude Opus 4.5 (2.9× as much).
Which scores higher on benchmarks?
GPT-5.3 Codex scores higher on the Capabilities Index (ECI): GPT-5.3 Codex 156.8 (#18 of 148), Claude Opus 4.5 150.1 (#48 of 148) and GPT-5.1 149.7 (#52 of 148). Their confidence ranges do not overlap (153.5–160.8 vs 147.9–153.0), so the gap is a real one. On individual benchmarks: SWE-bench Verified — Claude Opus 4.5 76.7%, GPT-5.3 Codex 74.8%, GPT-5.1 68.0%.
Which is better for coding?
Claude Opus 4.5 resolves more real GitHub issues on SWE-bench Verified: Claude Opus 4.5 76.7%, GPT-5.3 Codex 74.8% and GPT-5.1 68.0%. All three support tool calling for agent workflows.
Which has the bigger context window?
GPT-5.3 Codex and GPT-5.1 have the largest context windows (400,000 and 400,000 tokens), against 200,000 for Claude Opus 4.5. Maximum output per response: Claude Opus 4.5 up to 64,000, GPT-5.3 Codex up to 128,000, GPT-5.1 up to 128,000 tokens.
Which can read images, PDFs, audio or video?
Claude Opus 4.5 accepts text, images and PDFs; GPT-5.3 Codex accepts text, images and PDFs; GPT-5.1 accepts text and images. Claude Opus 4.5 handles the widest range of inputs.
Are any of these open source?
No. Claude Opus 4.5, GPT-5.3 Codex and GPT-5.1 are proprietary and only available through APIs and apps.
Which is newer?
GPT-5.3 Codex is the newest, released Feb 5, 2026. Claude Opus 4.5 came out Nov 24, 2025; GPT-5.1 came out Nov 13, 2025. Knowledge cutoff: Claude Opus 4.5 May 2025, GPT-5.3 Codex Aug 31, 2025, GPT-5.1 Sep 30, 2024.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
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