# GPT-5.1-Codex vs GPT-5.3 Instant

> Side-by-side benchmark comparison for GPT-5.1-Codex and GPT-5.3 Instant across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-1-codex-vs-gpt-5-3-instant
- Last updated: September 8, 2026

- Shared sourced benchmarks: 0
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

No benchmark verdict yet: there is no shared sourced benchmark row for GPT-5.1-Codex and GPT-5.3 Instant.

## Summary

- GPT-5.1-Codex and GPT-5.3 Instant do not currently share a sourced benchmark row. The mirror therefore compares metadata, pricing, context windows, and each model's separately reported coverage without naming a benchmark winner.

## Model Snapshot

| Property | GPT-5.1-Codex | GPT-5.3 Instant |
|----------|----------|----------|
| Creator | OpenAI | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 400K | 400K |
| Independent public score (not head-to-head) | 48.4 | 57.08 |
| Benchmarks Covered | 3 | 0 |
| Pricing (input/output) | $1.25 / $10.00 | $1.75 / $14.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 49.2 (Estimated · #63/152)
- GPT-5.3 Instant public-lane score: Coming soon

| Benchmark | GPT-5.1-Codex | GPT-5.3 Instant | Winner |
|-----------|-----------|-----------|--------|
| Gert Labs | 49.68% | Coming soon | Coming soon |
| JobBench | 26.2% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 45.3 (Estimated · #90/151)
- GPT-5.3 Instant public-lane score: Coming soon

| Benchmark | GPT-5.1-Codex | GPT-5.3 Instant | Winner |
|-----------|-----------|-----------|--------|
| Vibe Code Bench | 13.12% | Coming soon | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 66.8 (Unranked · 1 rankable row)
- GPT-5.3 Instant public-lane score: Coming soon

### Reasoning

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 68.6 (Unranked · 2 rankable rows)
- GPT-5.3 Instant public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 52 (Estimated · #70/182)
- GPT-5.3 Instant public-lane score: Coming soon

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 85.6 (#41/121)
- GPT-5.3 Instant public-lane score: Coming soon

## FAQ

### Can I compare GPT-5.1-Codex and GPT-5.3 Instant on BenchLM yet?

Not fully yet. BenchLM is tracking both models, but sourced benchmark coverage is still incomplete for a fair score-level comparison.

### Why does this page show "coming soon" values?

BenchLM only calls winners when public benchmark coverage is available on both sides of the comparison.

## Related Comparisons

- [GPT-5.1-Codex vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gpt-5-1-codex)
- [GPT-5.3 Instant vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gpt-5-3-instant)
- [GPT-5.1-Codex vs GPT-6 Astra](/compare/gpt-5-1-codex-vs-gpt-6-astra)
- [GPT-5.3 Instant vs GPT-6 Astra](/compare/gpt-5-3-instant-vs-gpt-6-astra)

## Explore More

- [GPT-5.1-Codex profile](/models/gpt-5-1-codex)
- [GPT-5.3 Instant profile](/models/gpt-5-3-instant)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)