Model comparison

GPT-5.3 Chat vs Mistral Medium 3.5

GPT-5.3 Chat is the stronger model overall, scoring 42.1 to 39.6 on the Noometry Index. Mistral Medium 3.5 costs 1.6× less per token, which makes it the better buy when GPT-5.3 Chat's lead doesn't matter for your workload.

Last verified October 10, 2026. 16 shared benchmarks.

GPT-5.3 Chat OpenAI

42.1

Rank #109 Confirmed

Mistral Medium 3.5

Mistral AI

39.6

Rank #151 Confirmed

Summary

They share 16 benchmarks with published results for both. GPT-5.3 Chat scores higher in 3 categories and Mistral Medium 3.5 in 5 categories; 6 gaps are clear of the uncertainty.
The widest gap is in reasoning, where GPT-5.3 Chat leads 27.3 to 16.6.
Mistral Medium 3.5 is cheaper at $1.50 / $7.50 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Chat.
Mistral Medium 3.5 accepts more context: 262K tokens versus 128K.
Mistral Medium 3.5 has downloadable open weights; the other is API-only.

Side by side

GPT-5.3 Chat and Mistral Medium 3.5 specifications
	GPT-5.3 Chat	Mistral Medium 3.5
Provider	OpenAI	Mistral AI
Noometry Index	42.1	39.6
Released	2026-03-03	—
Weights	Proprietary	Open
Context window	128K	262K
Max output	16K	210K
Input $ / M tokens	$1.75	$1.50
Output $ / M tokens	$14	$7.50
Results tracked	18	22

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Category by category

Coding GPT-5.3 Chat leads

GPT-5.3 Chat: 40.8 (#124), Mistral Medium 3.5: 35.7 (#208)

Coding benchmarks
Benchmark	GPT-5.3 Chat	Mistral Medium 3.5
LMArena Coding	1408	1461
LMArena WebDev	—	1263

Reasoning GPT-5.3 Chat leads

GPT-5.3 Chat: 27.3 (#105), Mistral Medium 3.5: 16.6 (#290)

Reasoning benchmarks
Benchmark	GPT-5.3 Chat	Mistral Medium 3.5
LMArena Hard Prompts	1399	1436
Kagi LLM Benchmark	—	41.4%
NYT Connections (extended)	—	12.9%
Epoch Capabilities Index	—	141.42

Math Too close to call

GPT-5.3 Chat: 35.4 (#146), Mistral Medium 3.5: 36.4 (#113)

Math benchmarks
Benchmark	GPT-5.3 Chat	Mistral Medium 3.5
LMArena Math	1389	1432

Knowledge Mistral Medium 3.5 leads

GPT-5.3 Chat: 38.2 (#137), Mistral Medium 3.5: 39.3 (#123)

Knowledge benchmarks
Benchmark	GPT-5.3 Chat	Mistral Medium 3.5
LMArena Expert	1397	1431

Multimodal Not comparable

GPT-5.3 Chat: —, Mistral Medium 3.5: 37.6 (#64)

Multimodal benchmarks
Benchmark	GPT-5.3 Chat	Mistral Medium 3.5
LMArena Vision	—	1222

Multilingual Mistral Medium 3.5 leads

GPT-5.3 Chat: 50.5 (#119), Mistral Medium 3.5: 52.1 (#93)

Multilingual benchmarks
Benchmark	GPT-5.3 Chat	Mistral Medium 3.5
LMArena Non-English	1383	1405
LMArena Chinese	1433	1443
LMArena French	1398	1448
LMArena German	1384	1453
LMArena Korean	1347	1387
LMArena Russian	1400	1396
LMArena Spanish	1371	1406
LMArena Japanese	1351	—

Instruction Following Mistral Medium 3.5 leads

GPT-5.3 Chat: 73.0 (#124), Mistral Medium 3.5: 74.7 (#87)

Instruction Following benchmarks
Benchmark	GPT-5.3 Chat	Mistral Medium 3.5
LMArena Instruction Following	1378	1414

Long Context Too close to call

GPT-5.3 Chat: 42.6 (#115), Mistral Medium 3.5: 43.2 (#101)

Long Context benchmarks
Benchmark	GPT-5.3 Chat	Mistral Medium 3.5
LMArena Longer Query	1396	1414

Writing & Preference GPT-5.3 Chat leads

GPT-5.3 Chat: 63.3 (#65), Mistral Medium 3.5: 58.6 (#113)

Writing & Preference benchmarks
Benchmark	GPT-5.3 Chat	Mistral Medium 3.5
LMArena Text	1389	1421
LMArena Creative Writing	1356	1372
LMArena Multi-Turn	1413	1423
EQ-Bench Creative Writing	1690	—
EQ-Bench 4	—	993

Frequently asked questions

Is GPT-5.3 Chat better than Mistral Medium 3.5?

Which is cheaper, GPT-5.3 Chat or Mistral Medium 3.5?

Mistral Medium 3.5 is cheaper. It lists at $1.50 per million input tokens and $7.50 per million output tokens; GPT-5.3 Chat lists at $1.75 and $14.

Is GPT-5.3 Chat or Mistral Medium 3.5 better for coding?

GPT-5.3 Chat scores higher on coding benchmarks: 40.8 versus 35.7 in the Noometry coding category.

Which has the bigger context window?

Mistral Medium 3.5 does, with 262K tokens against 128K.

How many benchmarks do GPT-5.3 Chat and Mistral Medium 3.5 share?

16 benchmarks have published results for both models. GPT-5.3 Chat has 18 scored results on Noometry and Mistral Medium 3.5 has 22.