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Mistral Medium 3.1 vs Step 3.5 Flash

Updated October 21, 2026. 35 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.

Replace Mistral Medium 3.1 Replace Step 3.5 Flash
Mistral Medium 3.1Mistral AI
Coding
No data
Overall
9.2
Output $/M
$2.00
25
Step 3.5 FlashStepFun
Coding
No data
Overall
17.0
Output $/M
$0.30
10
vs boards won of 35 shared

Decision reading

Neither model has a coding score yet, so the two cannot be ranked on coding.

Mistral Medium 3.1 has the edge where what matters is Terminal-Bench Hard (Artificial Analysis run) or LMArena Text: coding, where it leads.

Model AMistral Medium 3.1Mistral AINot benchmarkedNo coding benchmarkNo cost per solved taskModel BStep 3.5 FlashStepFunNot benchmarkedNo coding benchmarkNo cost per solved task
Shared results
35
Mistral Medium 3.1 only
39
Step 3.5 Flash only
0
Like-for-like categories
7 of 9

Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

At a glance

Coding index
Mistral Medium 3.1 not benchmarked, Step 3.5 Flash not benchmarked.
Widest category
Agentic work, 53.8 points apart on average over 1 shared benchmark.
Widest single gap
τ²-Bench Telecom: Mistral Medium 3.1 40.6% against Step 3.5 Flash 94.4%, 53.8 points apart on a 0 to 100 scale.
Output price
Mistral Medium 3.1 $2.00 against Step 3.5 Flash $0.30 per million output tokens, 6.7x apart.
Context window
Mistral Medium 3.1 takes 131K tokens, Step 3.5 Flash 262K.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
CategoryMistral Medium 3.1BarsStep 3.5 FlashTies
Coding12
Intelligence01
Agentic work01
Reasoning23
Math11
Knowledge40
General172
All shared boards2510
CodingLike-for-likeSix of these boards feed the Vibe Coding Index12
Coding benchmarks for Mistral Medium 3.1 and Step 3.5 Flash
BenchmarkMistral Medium 3.1Step 3.5 FlashLeader
AA Coding Index20.5Not measuredOnly Mistral Medium 3.1 measured
LiveCodeBench (Vals AI)44.8%Not measuredOnly Mistral Medium 3.1 measured
LiveCodeBench (Artificial Analysis run)40.6%Not measuredOnly Mistral Medium 3.1 measured
SciCode32.4%Not measuredOnly Mistral Medium 3.1 measured
Terminal-Bench Hard (Artificial Analysis run)10.6%32.6%Step 3.5 Flash
ALE-Bench210.2Not measuredOnly Mistral Medium 3.1 measured
LMArena Text: coding14331436Step 3.5 Flash
LMArena Text: software and IT14361434Mistral Medium 3.1
Neither model has a result on the other 30 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
Intelligence benchmarks for Mistral Medium 3.1 and Step 3.5 Flash
BenchmarkMistral Medium 3.1Step 3.5 FlashLeader
AA Intelligence Index9.217.0Step 3.5 Flash
Neither model has a result on the other 1 board here
Agentic workLike-for-likePublic boards, shown as published, kept out of the index01
Agentic work benchmarks for Mistral Medium 3.1 and Step 3.5 Flash
BenchmarkMistral Medium 3.1Step 3.5 FlashLeader
AA Agentic Index1.9Not measuredOnly Mistral Medium 3.1 measured
τ²-Bench Telecom40.6%94.4%Step 3.5 Flash
Neither model has a result on the other 37 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index23
Reasoning benchmarks for Mistral Medium 3.1 and Step 3.5 Flash
BenchmarkMistral Medium 3.1Step 3.5 FlashLeader
MMMU Pro (Vals AI)63.0%Not measuredOnly Mistral Medium 3.1 measured
GPQA Diamond (Artificial Analysis run)58.8%83.1%Step 3.5 Flash
Humanity's Last Exam (Artificial Analysis run)4.7%24.5%Step 3.5 Flash
LMArena Text: hard prompts14261411Mistral Medium 3.1
LMArena Text: expert14081421Step 3.5 Flash
LMArena Text: hard prompts in English14351421Mistral Medium 3.1
LMArena Vision: diagrams1175Not measuredOnly Mistral Medium 3.1 measured
LMArena Vision: homework1165Not measuredOnly Mistral Medium 3.1 measured
Neither model has a result on the other 13 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index11
Math benchmarks for Mistral Medium 3.1 and Step 3.5 Flash
BenchmarkMistral Medium 3.1Step 3.5 FlashLeader
AIME42.3%Not measuredOnly Mistral Medium 3.1 measured
MATH 500 (Vals AI)87.0%Not measuredOnly Mistral Medium 3.1 measured
MGSM (Vals AI)90.9%Not measuredOnly Mistral Medium 3.1 measured
AA Math Index38.3Not measuredOnly Mistral Medium 3.1 measured
AIME 2025 (Artificial Analysis run)38.3%Not measuredOnly Mistral Medium 3.1 measured
LMArena Text: math14081408Mistral Medium 3.1
LMArena Text: mathematical work14121421Step 3.5 Flash
Neither model has a result on the other 6 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index40
Knowledge benchmarks for Mistral Medium 3.1 and Step 3.5 Flash
BenchmarkMistral Medium 3.1Step 3.5 FlashLeader
MMLU Pro75.3%Not measuredOnly Mistral Medium 3.1 measured
LegalBench (Vals AI)62.0%Not measuredOnly Mistral Medium 3.1 measured
CorpFin (Vals AI)50.7%Not measuredOnly Mistral Medium 3.1 measured
TaxEval (Vals AI)70.3%Not measuredOnly Mistral Medium 3.1 measured
MortgageTax (Vals AI)36.5%Not measuredOnly Mistral Medium 3.1 measured
MedQA (Vals AI)78.2%Not measuredOnly Mistral Medium 3.1 measured
MMLU Pro (Artificial Analysis run)68.3%Not measuredOnly Mistral Medium 3.1 measured
LMArena Text: science14441415Mistral Medium 3.1
LMArena Text: medicine and healthcare14491408Mistral Medium 3.1
LMArena Text: legal and government14391408Mistral Medium 3.1
LMArena Text: business and finance14181394Mistral Medium 3.1
Neither model has a result on the other 6 boards here
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
Web design benchmarks for Mistral Medium 3.1 and Step 3.5 Flash
BenchmarkMistral Medium 3.1Step 3.5 FlashLeader
Design Arena: websites1133Not measuredOnly Mistral Medium 3.1 measured
Design Arena: UI components1099Not measuredOnly Mistral Medium 3.1 measured
Design Arena: game dev1074Not measuredOnly Mistral Medium 3.1 measured
Design Arena: data viz1144Not measuredOnly Mistral Medium 3.1 measured
Design Arena: 3D1081Not measuredOnly Mistral Medium 3.1 measured
Design Arena: all code categories1120Not measuredOnly Mistral Medium 3.1 measured
Design Arena: SVG993Not measuredOnly Mistral Medium 3.1 measured
Design Arena: ASCII art997Not measuredOnly Mistral Medium 3.1 measured
Neither model has a result on the other 1 board here
GeneralLike-for-likePublic boards, shown as published, kept out of the index172
General benchmarks for Mistral Medium 3.1 and Step 3.5 Flash
BenchmarkMistral Medium 3.1Step 3.5 FlashLeader
IFBench39.8%66.5%Step 3.5 Flash
Long context reasoning (AA-LCR)42.7%63.0%Step 3.5 Flash
DTBench67.5%Not measuredOnly Mistral Medium 3.1 measured
LMCA19.1%Not measuredOnly Mistral Medium 3.1 measured
LMArena Text14241403Mistral Medium 3.1
LMArena Text: instruction following13981385Mistral Medium 3.1
LMArena Text: creative writing13911357Mistral Medium 3.1
LMArena Vision1172Not measuredOnly Mistral Medium 3.1 measured
LMArena Text: English14381417Mistral Medium 3.1
LMArena Text: non-English14081385Mistral Medium 3.1
LMArena Text: Chinese14471446Mistral Medium 3.1
LMArena Text: German14321405Mistral Medium 3.1
LMArena Text: Japanese13791353Mistral Medium 3.1
LMArena Text: Korean13801351Mistral Medium 3.1
LMArena Text: French14601421Mistral Medium 3.1
LMArena Text: Spanish14331419Mistral Medium 3.1
LMArena Text: Russian14111385Mistral Medium 3.1
LMArena Text: Polish14301389Mistral Medium 3.1
LMArena Text: multi-turn14181404Mistral Medium 3.1
LMArena Text: longer queries14061402Mistral Medium 3.1
LMArena Text: writing and language13951372Mistral Medium 3.1
LMArena Text: entertainment and media13901360Mistral Medium 3.1
LMArena Vision: English1179Not measuredOnly Mistral Medium 3.1 measured
LMArena Vision: Chinese1190Not measuredOnly Mistral Medium 3.1 measured
LMArena Vision: reading text1175Not measuredOnly Mistral Medium 3.1 measured
LMArena Vision: humor1168Not measuredOnly Mistral Medium 3.1 measured
LMArena Vision: captioning1145Not measuredOnly Mistral Medium 3.1 measured
LMArena Vision: recognizing things1147Not measuredOnly Mistral Medium 3.1 measured
LMArena Vision: creative writing1200Not measuredOnly Mistral Medium 3.1 measured
Neither model has a result on the other 17 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Mistral Medium 3.1 and Step 3.5 Flash
BenchmarkMistral Medium 3.1Step 3.5 FlashLeader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Mistral Medium 3.1$0.0014Fits in one request
Step 3.5 Flash$0.0003Fits in one request

Step 3.5 Flash costs less

Repository review

50K input + 3K output tokens

Mistral Medium 3.1$0.026Fits in one request
Step 3.5 Flash$0.0059Fits in one request

Step 3.5 Flash costs less

Agent loop

200K input + 10K output tokens

Mistral Medium 3.1$0.100Exceeds the context window
Step 3.5 Flash$0.023Fits in one request

Step 3.5 Flash costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Mistral Medium 3.1 and Step 3.5 Flash
SpecificationMistral Medium 3.1StepFun Step 3.5 Flash
MakerMistral AIStepFun
WeightsNo public weights listedOpen weights
ReleasedAugust 13, 2025January 29, 2026
Context window131K262K
Input $/Mtok$0.40$0.10
Output $/Mtok$2.00$0.30
Coding indexNot benchmarkedNot benchmarked
Independent measurements behind it00
Cost per solved taskNot computableNot computable
SourceOpenRouter listingOpenRouter listing

Questions

Is Mistral Medium 3.1 better than Step 3.5 Flash for coding?

Neither model has a coding score yet, so the two cannot be ranked on coding. Mistral Medium 3.1 has the edge where what matters is Terminal-Bench Hard (Artificial Analysis run) or LMArena Text: coding, where it leads.

Which is cheaper, Mistral Medium 3.1 or Step 3.5 Flash?

Mistral Medium 3.1 costs $0.40 per million input tokens and $2.00 per million output tokens; Step 3.5 Flash costs $0.10 and $0.30. Cost per solved task is known for neither of them.

Which has the bigger context window, Mistral Medium 3.1 or Step 3.5 Flash?

Step 3.5 Flash, with 262K tokens against 131K.

How many benchmarks is the Mistral Medium 3.1 vs Step 3.5 Flash comparison based on?

35 benchmarks have a result for both models as of October 21, 2026. Mistral Medium 3.1's coding index rests on 0 independent benchmarks and Step 3.5 Flash's on 0. Where only one model has a result, the page says so instead of naming a winner.

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