Model comparison
Claude 4 Sonnet vs GPT-5.3 Codex
Head-to-head evidence from 16 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude 4 Sonnet #158 (Supported); GPT-5.3 Codex #26 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude 4 Sonnet and GPT-5.3 Codex share 16 comparable benchmark results. 1 of 8 categories are comparable. 0 results are unique to Claude 4 Sonnet; 5 to GPT-5.3 Codex.
Updated July 20, 2026- Shared results
- 16
- Claude 4 Sonnet only
- 0
- GPT-5.3 Codex only
- 5
- Comparable categories
- 1 / 8
Pick GPT-5.3 Codex if you want the stronger benchmark profile. Claude 4 Sonnet only becomes the better choice if coding is the priority or you would rather avoid the extra latency and token burn of a reasoning model.
Confidence note. This is a partial-evidence comparison with 16 shared benchmark results across 6 evidence categories; 1 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
GPT-5.3 Codex is clearly ahead on the BenchAlign aggregate, 66.69 to 42.79. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude 4 Sonnet is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $1.75 input / $14.00 output per 1M tokens for GPT-5.3 Codex. GPT-5.3 Codex is the reasoning model in the pair, while Claude 4 Sonnet is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. GPT-5.3 Codex gives you the larger context window at 400K, compared with 200K for Claude 4 Sonnet.
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 4 Sonnet | Δ | GPT-5.3 Codex |
|---|---|---|---|
| Coding | Claude 4 Sonnet72.7 | Margin← 5.5 | GPT-5.3 Codex67.2 |
| Agentic | Claude 4 SonnetNot measured | MarginNo overlap | GPT-5.3 Codex71.4 |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
SWE-bench Verified
CodingA 72.7%B 85%Winner: GPT-5.3 CodexΔ 12.3SWE-bench Verified: Claude 4 Sonnet scored 72.7%; GPT-5.3 Codex scored 85%. GPT-5.3 Codex wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude 4 Sonnet | GPT-5.3 Codex | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude 4 Sonnet$3 input / $15 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 4 Sonnet40 tok/s | GPT-5.3 Codex79 tok/s | GPT-5.3 Codex has the higher measured throughput. |
| First-answer latencyseconds to first token | Claude 4 Sonnet1.33 s | GPT-5.3 Codex88.26 s | Claude 4 Sonnet reaches the first token sooner. |
| Context windowmaximum listed tokens | Claude 4 Sonnet200K | GPT-5.3 Codex400K | GPT-5.3 Codex lists the larger context window. |
Benchmark Deep Dive
Agentic5 benchmarks
CodingClaude 4 Sonnet wins5 benchmarks
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | Claude 4 Sonnet | GPT-5.3 Codex | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 25.5% | 44.3% | GPT-5.3 Codex leads |
| AA-GPQA DiamondSource | 68.3% | 91.5% | GPT-5.3 Codex leads |
| AA-HLESource | 4.0% | 39.9% | GPT-5.3 Codex leads |
| AA-Omniscience IndexSource | -9.2% | 9.9% | GPT-5.3 Codex leads |
| AA-Omniscience AccuracySource | 22.4% | 51.8% | GPT-5.3 Codex leads |
| AA-Omniscience Hallucination RateSource | 40.8% | 86.9% | Claude 4 Sonnet leads |
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | Claude 4 Sonnet | GPT-5.3 Codex | Result |
|---|---|---|---|
| AA-IFBenchSource | 45.4% | 75.4% | GPT-5.3 Codex leads |
Frequently Asked Questions (2)
Which is better, Claude 4 Sonnet or GPT-5.3 Codex?
GPT-5.3 Codex is ahead on BenchLM's BenchAlign leaderboard, 66.69 to 42.79. The biggest single separator in this matchup is SWE-bench Verified, where the scores are 72.7% and 85%.
Which is better for coding, Claude 4 Sonnet or GPT-5.3 Codex?
Claude 4 Sonnet has the edge for coding in this comparison, averaging 72.7 versus 67.2. Inside this category, AA-SciCode is the benchmark that creates the most daylight between them.
Related Comparisons
Choose a model with this week’s evidence
Join 2,000+ readers for ranking moves, pricing changes, and the claims that still need proof.
One email each week. Unsubscribe anytime.