# DeepSeek-V3.1 vs GPT-5-Codex

> DeepSeek-V3.1 is the stronger model overall, scoring 42.8 to 37.9 on the Noometry Index.

- Canonical page: https://noometry.com/compare/deepseek-v3-1-vs-gpt-5-codex
- Last updated: 2026-10-11
- Shared benchmarks: 2

## Summary

- They share 2 benchmarks with published results for both. DeepSeek-V3.1 scores higher in 0 categories and GPT-5-Codex in 2 categories; 2 gaps are clear of the uncertainty.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 53.2% for DeepSeek-V3.1 and 70.3% for GPT-5-Codex.
- DeepSeek-V3.1 is cheaper at $0.25 / $0.95 per million input/output tokens, against $1.25 / $10 for GPT-5-Codex.
- GPT-5-Codex accepts more context: 400K tokens versus 164K.
- DeepSeek-V3.1 has downloadable open weights; the other is API-only.

## Snapshot

| | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Noometry Index | 42.8 | 37.9 |
| Rank | 108 | 192 |
| Context | 164K | 400K |
| Input $/M | $0.25 | $1.25 |
| Output $/M | $0.95 | $10 |
| Weights | Open | Proprietary |

## Coding

- DeepSeek-V3.1: 40.3 (#144)
- GPT-5-Codex: 42.4 (#103)

| Benchmark | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| WeirdML | 38.4% | 54.5% |
| LMArena Coding | 1417 | — |

## Agentic & Tool Use

- DeepSeek-V3.1: —
- GPT-5-Codex: 31.0 (#72)

| Benchmark | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| Terminal-Bench | — | 44.3% |

## Reasoning

- DeepSeek-V3.1: 27.9 (#110)
- GPT-5-Codex: 30.9 (#83)

| Benchmark | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| Kagi LLM Benchmark | 53.2% | 70.3% |
| SimpleBench | 40% | — |
| LMArena Hard Prompts | 1417 | — |
| DTBench | 82.7% | — |
| LMCA | 24.3% | — |
| Epoch Capabilities Index | 139.92 | — |
| ForecastBench | 58 | — |

## Math

- DeepSeek-V3.1: 38.9 (#122)
- GPT-5-Codex: —

| Benchmark | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| LMArena Math | 1420 | — |

## Knowledge

- DeepSeek-V3.1: 43.7 (#90)
- GPT-5-Codex: —

| Benchmark | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| Vectara Hallucination Rate | 5.5% | — |
| LMArena Expert | 1405 | — |

## Multilingual

- DeepSeek-V3.1: 51.6 (#106)
- GPT-5-Codex: —

| Benchmark | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| LMArena Non-English | 1400 | — |
| LMArena Chinese | 1469 | — |
| LMArena French | 1447 | — |
| LMArena German | 1411 | — |
| LMArena Japanese | 1378 | — |
| LMArena Korean | 1337 | — |
| LMArena Russian | 1405 | — |
| LMArena Spanish | 1431 | — |

## Instruction Following

- DeepSeek-V3.1: 73.9 (#110)
- GPT-5-Codex: —

| Benchmark | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| LMArena Instruction Following | 1400 | — |

## Long Context

- DeepSeek-V3.1: 36.3 (#232)
- GPT-5-Codex: —

| Benchmark | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| Fiction.LiveBench | 52.8% | — |
| LMArena Longer Query | 1422 | — |

## Writing & Preference

- DeepSeek-V3.1: 60.3 (#98)
- GPT-5-Codex: —

| Benchmark | DeepSeek-V3.1 | GPT-5-Codex |
|---|---|---|
| LMArena Text | 1420 | — |
| LMArena Creative Writing | 1401 | — |
| EQ-Bench Creative Writing | 1436 | — |
| LMArena Multi-Turn | 1408 | — |

## FAQ

### Is DeepSeek-V3.1 better than GPT-5-Codex?

DeepSeek-V3.1 is the stronger model overall, scoring 42.8 to 37.9 on the Noometry Index.

### Which is cheaper, DeepSeek-V3.1 or GPT-5-Codex?

DeepSeek-V3.1 is cheaper. It lists at $0.25 per million input tokens and $0.95 per million output tokens; GPT-5-Codex lists at $1.25 and $10.

### Is DeepSeek-V3.1 or GPT-5-Codex better for coding?

GPT-5-Codex scores higher on coding benchmarks: 42.4 versus 40.3 in the Noometry coding category.

### Which has the bigger context window?

GPT-5-Codex does, with 400K tokens against 164K.

### How many benchmarks do DeepSeek-V3.1 and GPT-5-Codex share?

2 benchmarks have published results for both models. DeepSeek-V3.1 has 27 scored results on Noometry and GPT-5-Codex has 3.