Model comparison
Gemini 3.5 Flash-Lite vs GPT-5.1-Codex
Head-to-head evidence from 10 shared benchmark results across 4 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Gemini 3.5 Flash-Lite unranked (Not scored); GPT-5.1-Codex #99 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Gemini 3.5 Flash-Lite and GPT-5.1-Codex share 10 comparable benchmark results. 0 of 8 categories are comparable. 11 results are unique to Gemini 3.5 Flash-Lite; 6 to GPT-5.1-Codex.
Updated July 21, 2026- Shared results
- 10
- Gemini 3.5 Flash-Lite only
- 11
- GPT-5.1-Codex only
- 6
- Comparable categories
- 0 / 8
Benchmark data for Gemini 3.5 Flash-Lite and GPT-5.1-Codex is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 10 shared benchmark results across 4 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.
Gemini 3.5 Flash-Lite has the larger context window at 1M, compared with 400K for GPT-5.1-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 3.5 Flash-Lite | Δ | GPT-5.1-Codex |
|---|---|---|---|
| Agentic | Gemini 3.5 Flash-Lite63.4 | MarginNo overlap | GPT-5.1-CodexNot measured |
| Coding | Gemini 3.5 Flash-Lite54.2 | MarginNo overlap | GPT-5.1-CodexNot measured |
| Reasoning | Gemini 3.5 Flash-Lite72.2 | MarginNo overlap | GPT-5.1-CodexNot measured |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Gemini 3.5 Flash-Lite | GPT-5.1-Codex | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Gemini 3.5 Flash-Lite$0.3 input / $2.5 output | GPT-5.1-CodexNot available | A complete price comparison is not available. |
| Generation speedtokens per second | Gemini 3.5 Flash-LiteNot available | GPT-5.1-CodexNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Gemini 3.5 Flash-LiteNot available | GPT-5.1-CodexNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Gemini 3.5 Flash-Lite1M | GPT-5.1-Codex400K | Gemini 3.5 Flash-Lite lists the larger context window. |
Benchmark Deep Dive
Agentic10 benchmarks
| Benchmark | Gemini 3.5 Flash-Lite | GPT-5.1-Codex | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 54% | — | Not comparable |
| OSWorld-VerifiedSource | 74% | — | Not comparable |
| GDPval-AASource | 1140 | — | Not comparable |
| AA Agentic IndexSource | 26.8% | — | Not comparable |
| GDPval-AASource | 32.0% | — | Not comparable |
| AA BriefcaseSource | 634 | — | Not comparable |
| AA Tau3 BankingSource | 16.5% | — | Not comparable |
| τ²-bench resultsSource | — | 83% | Not comparable |
| Gert LabsSource | — | 49.68% | Not comparable |
| JobBenchSource | — | 26.2% | Not comparable |
Coding5 benchmarks
Reasoning3 benchmarks
Knowledge6 benchmarks
| Benchmark | Gemini 3.5 Flash-Lite | GPT-5.1-Codex | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 36.5% | 34.7% | Gemini 3.5 Flash-Lite leads |
| AA-GPQA DiamondSource | 83.8% | 86.0% | GPT-5.1-Codex leads |
| AA-HLESource | 17.5% | 23.4% | GPT-5.1-Codex leads |
| AA-Omniscience IndexSource | 6.9% | -6.0% | Gemini 3.5 Flash-Lite leads |
| AA-Omniscience AccuracySource | 30.3% | 39.2% | GPT-5.1-Codex leads |
| AA-Omniscience Hallucination RateSource | 33.5% | 74.4% | Gemini 3.5 Flash-Lite leads |
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | Gemini 3.5 Flash-Lite | GPT-5.1-Codex | Result |
|---|---|---|---|
| AA-IFBenchSource | — | 70.0% | Not comparable |
Frequently Asked Questions (3)
Can I compare Gemini 3.5 Flash-Lite and GPT-5.1-Codex 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 Gemini 3.5 Flash-Lite and GPT-5.1-Codex today?
Gemini 3.5 Flash-Lite: $0.30 input / $2.50 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
Related Comparisons
Explore More
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.