Claude Opus 4.5vsGPT-5.3-Codex
Claude Opus 4.5 | GPT-5.3-Codex | |
|---|---|---|
| API pricingUSD per 1M tokens · lower wins | ||
Input priceWhat you pay for everything you send the model — your question, plus any documents or earlier conversation you include with it. | $5.00 | $1.75 |
Output priceWhat you pay for the text the model writes back. It is normally the dearer half: producing an answer costs more than reading one. | $25.00 | $14.00 |
Cached input priceA reduced rate for text you send over and over. If every request starts with the same instructions or the same document, the provider keeps a copy ready and charges less to read it again. | $0.50 | $0.175 |
Cheapest inputLowest input rate across third-party providers, excluding the lab itself. The cheapest endpoint may run a quantised build or a shorter context — see "Available from" on the model page. | $5.00Amazon Bedrock | $1.75Azure |
Cheapest outputLowest output rate across third-party providers, excluding the lab itself. May come from a different provider than the cheapest input. | $25.00Amazon Bedrock | $14.00Azure |
| Benchmarks | ||
BullshitBench v2Nonsense detection — Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 90% | 24% |
SWE-Bench VerifiedCoding — Real coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 80.9% | 85% |
| BenchmarksPublished by one model only | ||
Next.js EvalsNext.js coding — Vercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better. | — | 81% |
GPQA DiamondScience — Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 87% | — |
| Overview | ||
| Company | Anthropic | OpenAI |
| Release date | Nov 24 2025 | Feb 5 2026 |
| Access | Proprietary | Proprietary |
Other comparisons
Frequently asked questions
Claude Opus 4.5 and GPT-5.3-Codex are evenly matched across the 2 benchmarks they both report (BullshitBench v2, SWE-Bench Verified). GPT-5.3-Codex is cheaper on both input and output: $1.75 vs $5.00 per million input tokens, and $14.00 vs $25.00 per million output tokens. Claude Opus 4.5 shipped 73 days before GPT-5.3-Codex, so benchmark comparisons should account for the intervening progress.
Published specifications for these two models are limited — see each model page for the latest details.
On BullshitBench v2, Claude Opus 4.5 leads at 90% vs GPT-5.3-Codex at 24%. On SWE-Bench Verified, GPT-5.3-Codex leads at 85% vs Claude Opus 4.5 at 80.9%.
Claude Opus 4.5 was released by Anthropic on Nov 24 2025.
GPT-5.3-Codex was released by OpenAI on Feb 5 2026.
GPT-5.3-Codex leads on SWE-Bench Verified — Claude Opus 4.5 80.9% vs GPT-5.3-Codex 85%.
GPT-5.3-Codex is cheaper on both input and output: $1.75 vs $5.00 per million input tokens, and $14.00 vs $25.00 per million output tokens. Rates are pay-as-you-go API prices verified on August 18, 2026.