Model comparison
Claude 3 Opus vs GPT-5.3 Codex
Head-to-head evidence from 4 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude 3 Opus #168 (Supported); GPT-5.3 Codex #26 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude 3 Opus and GPT-5.3 Codex share 4 comparable benchmark results. 0 of 8 categories are comparable. 1 result is unique to Claude 3 Opus; 17 to GPT-5.3 Codex.
Updated July 20, 2026- Shared results
- 4
- Claude 3 Opus only
- 1
- GPT-5.3 Codex only
- 17
- Comparable categories
- 0 / 8
Benchmark data for Claude 3 Opus and GPT-5.3 Codex is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 4 shared benchmark results across 2 evidence categories; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
Claude 3 Opus is priced at $15.00 input / $75.00 output per 1M tokens, versus $1.75 input / $14.00 output per 1M tokens for GPT-5.3 Codex. GPT-5.3 Codex has the larger context window at 400K, compared with 200K for Claude 3 Opus.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | Claude 3 Opus | Δ | GPT-5.3 Codex |
|---|---|---|---|
| Agentic | Claude 3 OpusNot measured | MarginNo overlap | GPT-5.3 Codex71.4 |
| Coding | Claude 3 OpusNot measured | MarginNo overlap | GPT-5.3 Codex67.2 |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude 3 Opus | GPT-5.3 Codex | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude 3 Opus$15 input / $75 output | GPT-5.3 Codex$1.75 input / $14 output | GPT-5.3 Codex has the lower combined listed price. |
| Generation speedtokens per second | Claude 3 OpusNot available | GPT-5.3 Codex79 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude 3 OpusNot available | GPT-5.3 Codex88.26 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude 3 Opus200K | GPT-5.3 Codex400K | GPT-5.3 Codex lists the larger context window. |
Benchmark Deep Dive
Agentic5 benchmarks
Coding6 benchmarks
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | Claude 3 Opus | GPT-5.3 Codex | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 11.8% | 44.3% | GPT-5.3 Codex leads |
| AA-GPQA DiamondSource | 48.9% | 91.5% | GPT-5.3 Codex leads |
| AA-HLESource | 3.1% | 39.9% | GPT-5.3 Codex leads |
| AA-Omniscience IndexSource | — | 9.9% | Not comparable |
| AA-Omniscience AccuracySource | — | 51.8% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 86.9% | Not comparable |
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | Claude 3 Opus | GPT-5.3 Codex | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 75.4% | Not comparable |
Frequently Asked Questions (3)
Can I compare Claude 3 Opus and GPT-5.3 Codex on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for Claude 3 Opus and GPT-5.3 Codex today?
Claude 3 Opus: $15.00 input / $75.00 output per 1M tokens GPT-5.3 Codex: $1.75 input / $14.00 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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