Model comparison
GPT-5.2-Codex vs o3-mini
Head-to-head evidence from 5 shared benchmark results across 3 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.2-Codex #66 (Supported); o3-mini #141 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.2-Codex and o3-mini share 5 comparable benchmark results. 0 of 8 categories are comparable. 10 results are unique to GPT-5.2-Codex; 5 to o3-mini.
Updated July 24, 2026- Shared results
- 5
- GPT-5.2-Codex only
- 10
- o3-mini only
- 5
- Comparable categories
- 0 / 8
Benchmark data for GPT-5.2-Codex and o3-mini is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 5 shared benchmark results across 3 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.
GPT-5.2-Codex is priced at $1.75 input / $14.00 output per 1M tokens, versus $1.10 input / $4.40 output per 1M tokens for o3-mini. GPT-5.2-Codex has the larger context window at 400K, compared with 200K for o3-mini.
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 | GPT-5.2-Codex | Δ | o3-mini |
|---|---|---|---|
| Coding | GPT-5.2-CodexNot measured | MarginNo overlap | o3-mini49.3 |
| Knowledge | GPT-5.2-CodexNot measured | MarginNo overlap | o3-mini77.2 |
| Inst. Following | GPT-5.2-CodexNot measured | MarginNo overlap | o3-mini93.9 |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.2-Codex | o3-mini | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.2-Codex$1.75 input / $14 output | o3-mini$1.1 input / $4.4 output | o3-mini has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.2-Codex123 tok/s | o3-mini160 tok/s | o3-mini has the higher measured throughput. |
| First-answer latencyseconds to first token | GPT-5.2-Codex87.34 s | o3-mini7.12 s | o3-mini reaches the first token sooner. |
| Context windowmaximum listed tokens | GPT-5.2-Codex400K | o3-mini200K | GPT-5.2-Codex lists the larger context window. |
Benchmark Deep Dive
Agentic3 benchmarks
Coding3 benchmarks
Reasoning2 benchmarks
Knowledge8 benchmarks
| Benchmark | GPT-5.2-Codex | o3-mini | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 40.1% | 19.0% | GPT-5.2-Codex leads |
| AA-GPQA DiamondSource | 89.9% | 74.8% | GPT-5.2-Codex leads |
| AA-HLESource | 33.5% | 8.7% | GPT-5.2-Codex leads |
| AA-Omniscience IndexSource | -2.5% | — | Not comparable |
| AA-Omniscience AccuracySource | 40.7% | — | Not comparable |
| AA-Omniscience Hallucination RateSource | 72.8% | — | Not comparable |
| MMLUSource | — | 86.9% | Not comparable |
| GPQASource | — | 77.2% | Not comparable |
Math1 benchmarks
| Benchmark | GPT-5.2-Codex | o3-mini | Result |
|---|---|---|---|
| AIME 2024Source | — | 87.3% | Not comparable |
Multimodal1 benchmarks
| Benchmark | GPT-5.2-Codex | o3-mini | Result |
|---|---|---|---|
| AA-MMMU-ProSource | 76.3% | — | Not comparable |
Frequently Asked Questions (3)
Can I compare GPT-5.2-Codex and o3-mini 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 GPT-5.2-Codex and o3-mini today?
GPT-5.2-Codex: $1.75 input / $14.00 output per 1M tokens o3-mini: $1.10 input / $4.40 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.