GPT-5.3 Codex vs Grok 4.5
Head-to-head comparison across 2benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Verdict
GPT-5.3 Codex leads for most workloads.
Based on BenchLM composite scores, July 2026.
GPT-5.3 Codex
82
Grok 4.5
75
Pick GPT-5.3 Codex if you want the stronger benchmark profile. Grok 4.5 only becomes the better choice if agentic is the priority or you want the cheaper token bill.
Category Radar
Head-to-Head by Category
Category Breakdown
| Benchmark | GPT-5.3 Codex | Δ | Grok 4.5 |
|---|---|---|---|
| Agentic | 71.4 | → 11.9 | 83.3 |
| Coding | 64.4 | → 0.3 | 64.7 |
Operational Comparison
GPT-5.3 Codex
Grok 4.5
$1.75 / $14
$2 / $6
79 t/s
N/A
88.26s
N/A
400K
500K
Quick Verdict
Pick GPT-5.3 Codex if you want the stronger benchmark profile. Grok 4.5 only becomes the better choice if agentic is the priority or you want the cheaper token bill.
GPT-5.3 Codex is clearly ahead on the provisional aggregate, 82 to 75. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.3 Codex is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $2.00 input / $6.00 output per 1M tokens for Grok 4.5. That is roughly 2.3x on output cost alone. Grok 4.5 gives you the larger context window at 500K, compared with 400K for GPT-5.3 Codex.
Benchmark Deep Dive
Frequently Asked Questions (3)
Which is better, GPT-5.3 Codex or Grok 4.5?
GPT-5.3 Codex is ahead on BenchLM's provisional leaderboard, 82 to 75. The biggest single separator in this matchup is SWE-bench Pro, where the scores are 56.8% and 64.7%.
Which is better for coding, GPT-5.3 Codex or Grok 4.5?
Grok 4.5 has the edge for coding in this comparison, averaging 64.7 versus 64.4. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.
Which is better for agentic tasks, GPT-5.3 Codex or Grok 4.5?
Grok 4.5 has the edge for agentic tasks in this comparison, averaging 83.3 versus 71.4. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
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