Model comparison
GPT-5.2-Codex vs Step 3.5 Flash
Head-to-head evidence from 0 shared benchmark results across 0 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.2-Codex #66 (Supported); Step 3.5 Flash #90 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.2-Codex and Step 3.5 Flash share 0 comparable benchmark results. 0 of 8 categories are comparable. 15 results are unique to GPT-5.2-Codex; 0 to Step 3.5 Flash.
Updated July 28, 2026- Shared results
- 0
- GPT-5.2-Codex only
- 15
- Step 3.5 Flash only
- 0
- Comparable categories
- 0 / 8
Benchmark data for GPT-5.2-Codex and Step 3.5 Flash is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 0 shared benchmark results across 0 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 does not have sourced benchmark coverage for Step 3.5 Flash yet. This comparison is currently limited to metadata such as context window, reasoning mode, and pricing where available.
GPT-5.2-Codex is priced at $1.75 input / $14.00 output per 1M tokens, versus $0.10 input / $0.30 output per 1M tokens for Step 3.5 Flash. GPT-5.2-Codex has the larger context window at 400K, compared with 256K for Step 3.5 Flash.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.2-Codex | Step 3.5 Flash | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.2-Codex$1.75 input / $14 output | Step 3.5 Flash$0.1 input / $0.3 output | Step 3.5 Flash has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.2-Codex123 tok/s | Step 3.5 Flash87 tok/s | GPT-5.2-Codex has the higher measured throughput. |
| First-answer latencyseconds to first token | GPT-5.2-Codex87.34 s | Step 3.5 Flash3.03 s | Step 3.5 Flash reaches the first token sooner. |
| Context windowmaximum listed tokens | GPT-5.2-Codex400K | Step 3.5 Flash256K | GPT-5.2-Codex lists the larger context window. |
Benchmark Deep Dive
Agentic3 benchmarks
Coding2 benchmarks
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | GPT-5.2-Codex | Step 3.5 Flash | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 40.1% | — | Not comparable |
| AA-GPQA DiamondSource | 89.9% | — | Not comparable |
| AA-HLESource | 33.5% | — | Not comparable |
| AA-Omniscience IndexSource | -2.5% | — | Not comparable |
| AA-Omniscience AccuracySource | 40.7% | — | Not comparable |
| AA-Omniscience Hallucination RateSource | 72.8% | — | Not comparable |
Multimodal1 benchmarks
| Benchmark | GPT-5.2-Codex | Step 3.5 Flash | Result |
|---|---|---|---|
| AA-MMMU-ProSource | 76.3% | — | Not comparable |
Inst. Following1 benchmarks
| Benchmark | GPT-5.2-Codex | Step 3.5 Flash | Result |
|---|---|---|---|
| AA-IFBenchSource | 77.6% | — | Not comparable |
Frequently Asked Questions (3)
Can I compare GPT-5.2-Codex and Step 3.5 Flash 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 Step 3.5 Flash today?
GPT-5.2-Codex: $1.75 input / $14.00 output per 1M tokens Step 3.5 Flash: $0.10 input / $0.30 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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The model to choose, the cheaper alternative, and the release we would wait on.
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