Model comparison

DeepSeek-V3.1 vs Devstral Small 2505

DeepSeek-V3.1 is the stronger model overall, scoring 42.8 to 34.3 on the Noometry Index. Devstral Small 2505 costs 2.8× less per token, which makes it the better buy when DeepSeek-V3.1's lead doesn't matter for your workload.

Last verified October 11, 2026. 1 shared benchmarks.

DeepSeek-V3.1

DeepSeek

42.8

Rank #108 Confirmed

Devstral Small 2505

Mistral AI

34.3

Rank #233 Reported

Summary

They share 1 benchmark with published results for both. DeepSeek-V3.1 scores higher in 2 categories and Devstral Small 2505 in 0 categories; 2 gaps are clear of the uncertainty.
The widest gap is in reasoning, where DeepSeek-V3.1 leads 27.9 to 19.7.
The biggest single-benchmark swing is Kagi LLM Benchmark: 53.2% for DeepSeek-V3.1 and 37.7% for Devstral Small 2505.
Devstral Small 2505 is cheaper at $0.10 / $0.30 per million input/output tokens, against $0.25 / $0.95 for DeepSeek-V3.1.
DeepSeek-V3.1 accepts more context: 164K tokens versus 128K.

Side by side

DeepSeek-V3.1 and Devstral Small 2505 specifications
	DeepSeek-V3.1	Devstral Small 2505
Provider	DeepSeek	Mistral AI
Noometry Index	42.8	34.3
Released	2025-08-21	2025-05-07
Weights	Open	Open
Context window	164K	128K
Max output	8K	128K
Input $ / M tokens	$0.25	$0.10
Output $ / M tokens	$0.95	$0.30
Results tracked	27	4

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Category by category

Coding DeepSeek-V3.1 leads

DeepSeek-V3.1: 40.3 (#144), Devstral Small 2505: 38.9 (#166)

Coding benchmarks
Benchmark	DeepSeek-V3.1	Devstral Small 2505
SWE-bench Verified (bash only)	—	56.4%
SciCode	—	28.8%
WeirdML	38.4%	—
LMArena Coding	1417	—

Reasoning DeepSeek-V3.1 leads

DeepSeek-V3.1: 27.9 (#110), Devstral Small 2505: 19.7 (#252)

Reasoning benchmarks
Benchmark	DeepSeek-V3.1	Devstral Small 2505
Kagi LLM Benchmark	53.2%	37.7%
SimpleBench	40%	—
CritPt	—	0%
LMArena Hard Prompts	1417	—
DTBench	82.7%	—
LMCA	24.3%	—
Epoch Capabilities Index	139.92	—
ForecastBench	58	—

Math Not comparable

DeepSeek-V3.1: 38.9 (#122), Devstral Small 2505: —

Math benchmarks
Benchmark	DeepSeek-V3.1	Devstral Small 2505
LMArena Math	1420	—

Knowledge Not comparable

DeepSeek-V3.1: 43.7 (#90), Devstral Small 2505: —

Knowledge benchmarks
Benchmark	DeepSeek-V3.1	Devstral Small 2505
Vectara Hallucination Rate	5.5%	—
LMArena Expert	1405	—

Multilingual Not comparable

DeepSeek-V3.1: 51.6 (#106), Devstral Small 2505: —

Multilingual benchmarks
Benchmark	DeepSeek-V3.1	Devstral Small 2505
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 Not comparable

DeepSeek-V3.1: 73.9 (#110), Devstral Small 2505: —

Instruction Following benchmarks
Benchmark	DeepSeek-V3.1	Devstral Small 2505
LMArena Instruction Following	1400	—

Long Context Not comparable

DeepSeek-V3.1: 36.3 (#232), Devstral Small 2505: —

Long Context benchmarks
Benchmark	DeepSeek-V3.1	Devstral Small 2505
Fiction.LiveBench	52.8%	—
LMArena Longer Query	1422	—

Writing & Preference Not comparable

DeepSeek-V3.1: 60.3 (#98), Devstral Small 2505: —

Writing & Preference benchmarks
Benchmark	DeepSeek-V3.1	Devstral Small 2505
LMArena Text	1420	—
LMArena Creative Writing	1401	—
EQ-Bench Creative Writing	1436	—
LMArena Multi-Turn	1408	—

Frequently asked questions

Is DeepSeek-V3.1 better than Devstral Small 2505?

Which is cheaper, DeepSeek-V3.1 or Devstral Small 2505?

Devstral Small 2505 is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; DeepSeek-V3.1 lists at $0.25 and $0.95.

Is DeepSeek-V3.1 or Devstral Small 2505 better for coding?

DeepSeek-V3.1 scores higher on coding benchmarks: 40.3 versus 38.9 in the Noometry coding category.

Which has the bigger context window?

DeepSeek-V3.1 does, with 164K tokens against 128K.

How many benchmarks do DeepSeek-V3.1 and Devstral Small 2505 share?

1 benchmark has published results for both models. DeepSeek-V3.1 has 27 scored results on Noometry and Devstral Small 2505 has 4.