Model comparison
Gemini 3.6 Flash vs GPT-5.3 Codex
Head-to-head evidence from 11 shared benchmark results across 5 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Gemini 3.6 Flash unranked (Not scored); GPT-5.3 Codex #26 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Gemini 3.6 Flash and GPT-5.3 Codex share 11 comparable benchmark results. 1 of 8 categories are comparable. 8 results are unique to Gemini 3.6 Flash; 10 to GPT-5.3 Codex.
Updated July 21, 2026- Shared results
- 11
- Gemini 3.6 Flash only
- 8
- GPT-5.3 Codex only
- 10
- Comparable categories
- 1 / 8
Treat this as a split decision. Gemini 3.6 Flash makes more sense if agentic is the priority or you want the cheaper token bill; GPT-5.3 Codex is the better fit if its strengths line up with your actual workload.
Confidence note. This is a partial-evidence comparison with 11 shared benchmark results across 5 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
Gemini 3.6 Flash and GPT-5.3 Codex finish on the same BenchAlign overall score, so this is less about a single winner and more about where the edge shows up. The BenchAlign headline says tie; the benchmark table is where the real choice happens.
GPT-5.3 Codex is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $1.50 input / $7.50 output per 1M tokens for Gemini 3.6 Flash. Gemini 3.6 Flash gives you the larger context window at 1M, compared with 400K for GPT-5.3 Codex.
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 | Gemini 3.6 Flash | Δ | GPT-5.3 Codex |
|---|---|---|---|
| Agentic | Gemini 3.6 Flash83.0 | Margin← 11.6 | GPT-5.3 Codex71.4 |
| Coding | Gemini 3.6 FlashNot measured | MarginNo overlap | GPT-5.3 Codex67.2 |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
OSWorld-Verified
AgenticA 83%B 64.7%Winner: Gemini 3.6 FlashΔ 18.3OSWorld-Verified: Gemini 3.6 Flash scored 83%; GPT-5.3 Codex scored 64.7%. Gemini 3.6 Flash wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Gemini 3.6 Flash | GPT-5.3 Codex | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Gemini 3.6 Flash$1.5 input / $7.5 output | GPT-5.3 Codex$1.75 input / $14 output | Gemini 3.6 Flash has the lower combined listed price. |
| Generation speedtokens per second | Gemini 3.6 FlashNot available | GPT-5.3 Codex79 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Gemini 3.6 FlashNot available | GPT-5.3 Codex88.26 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Gemini 3.6 Flash1M | GPT-5.3 Codex400K | Gemini 3.6 Flash lists the larger context window. |
Benchmark Deep Dive
AgenticGemini 3.6 Flash wins11 benchmarks
| Benchmark | Gemini 3.6 Flash | GPT-5.3 Codex | Result |
|---|---|---|---|
| OSWorld-VerifiedSource | 83% | 64.7% | Gemini 3.6 Flash leads |
| GDPval-AASource | 1421 | — | Not comparable |
| AA Agentic IndexSource | 38.7% | — | Not comparable |
| GDPval-AASource | 46.1% | — | Not comparable |
| AA BriefcaseSource | 961 | — | Not comparable |
| AA Tau3 BankingSource | 24.5% | — | Not comparable |
| aaTerminalBench21Source | 77.5% | — | Not comparable |
| Terminal-Bench 2.0Source | — | 77.3% | Not comparable |
| τ²-bench resultsSource | — | 86% | Not comparable |
| Gert LabsSource | — | 57.47% | Not comparable |
| JobBenchSource | — | 33.7% | Not comparable |
Coding7 benchmarks
| Benchmark | Gemini 3.6 Flash | GPT-5.3 Codex | Result |
|---|---|---|---|
| deepSweSource | 49% | — | Not comparable |
| AA Coding IndexSource | 69.2% | — | Not comparable |
| AA-SciCodeSource | 52.7% | 53.2% | GPT-5.3 Codex leads |
| SWE-bench VerifiedSource | — | 85% | Not comparable |
| SWE-bench ProSource | — | 56.8% | Not comparable |
| SWE-RebenchSource | — | 58.2% | Not comparable |
| Vibe Code BenchSource | — | 61.77% | Not comparable |
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | Gemini 3.6 Flash | GPT-5.3 Codex | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 50.1% | 44.3% | Gemini 3.6 Flash leads |
| AA-GPQA DiamondSource | 92.8% | 91.5% | Gemini 3.6 Flash leads |
| AA-HLESource | 38.3% | 39.9% | GPT-5.3 Codex leads |
| AA-Omniscience IndexSource | 23.5% | 9.9% | Gemini 3.6 Flash leads |
| AA-Omniscience AccuracySource | 50.2% | 51.8% | GPT-5.3 Codex leads |
| AA-Omniscience Hallucination RateSource | 53.5% | 86.9% | Gemini 3.6 Flash leads |
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | Gemini 3.6 Flash | GPT-5.3 Codex | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 75.4% | Not comparable |
Frequently Asked Questions (2)
Which is better, Gemini 3.6 Flash or GPT-5.3 Codex?
Gemini 3.6 Flash and GPT-5.3 Codex are tied on the BenchAlign overall score, so the right pick depends on which category matters most for your use case.
Which is better for agentic tasks, Gemini 3.6 Flash or GPT-5.3 Codex?
Gemini 3.6 Flash has the edge for agentic tasks in this comparison, averaging 83 versus 71.4. Inside this category, OSWorld-Verified is the benchmark that creates the most daylight between them.
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