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Qwen3.5-Flash vs Solar Pro 4

Qwen3.5-Flash costs 2.3x less per output token than Solar Pro 4 ($0.26 vs $0.60 per million). Updated October 22, 2026; 32 benchmarks have a result for both.

Replace Qwen3.5-Flash Replace Solar Pro 4
Qwen3.5-FlashQwen
Coding
41.1
Overall
50.1
Output $/M
$0.26
19
Solar Pro 4Upstage
Coding
No data
Overall
No data
Output $/M
$0.60
13
vs boards won of 32 shared

Qwen3.5-Flash or Solar Pro 4: which to pick

Only Qwen3.5-Flash has a coding score, 41.1 on the Vibe Coding Index; Solar Pro 4 has none, so the two cannot be ranked on coding.

Pick Solar Pro 4 for work measured by LMArena WebDev or LMArena Text: coding, where it leads.

Model AQwen3.5-FlashQwen41.1/1002 independent benchmarks$0.40 per solved taskModel BSolar Pro 4UpstageNot benchmarked1 independent benchmarkNo cost per solved task
Shared results
32
Qwen3.5-Flash only
23
Solar Pro 4 only
13
Like-for-like categories
5 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

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
Qwen3.5-Flash 41.1 from 2 benchmarks, Solar Pro 4 not benchmarked.
Widest category
Coding, 10.6 points apart on average over 6 shared benchmarks.
Widest single gap
LMArena WebDev: React: Qwen3.5-Flash 1229 against Solar Pro 4 1363, 22.3 points apart on a 0 to 100 scale.
Output price
Qwen3.5-Flash $0.26 against Solar Pro 4 $0.60 per million output tokens, 2.3x apart.
Context window
Qwen3.5-Flash takes 1M tokens, Solar Pro 4 524K.

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
CategoryQwen3.5-FlashBarsSolar Pro 4Ties
Coding15
Reasoning12
Math02
Knowledge40
General134
All shared boards1913
CodingLike-for-likeSix of these boards feed the Vibe Coding Index15
Coding benchmarks for Qwen3.5-Flash and Solar Pro 4
BenchmarkQwen3.5-FlashSolar Pro 4Leader
LMArena WebDev12441371Solar Pro 4
AA Coding IndexNot measured52.7Only Solar Pro 4 measured
LiveCodeBench (Vals AI)83.3%Not measuredOnly Qwen3.5-Flash measured
SWE-bench Verified (Vals AI)64.4%Not measuredOnly Qwen3.5-Flash measured
SciCodeNot measured48.0%Only Solar Pro 4 measured
ALE-Bench265.9179.3Qwen3.5-Flash
LMArena Text: coding14121438Solar Pro 4
LMArena Text: software and IT14161431Solar Pro 4
LMArena WebDev: React12291363Solar Pro 4
LMArena WebDev: HTML12911371Solar Pro 4
Neither model has a result on the other 33 boards here
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index2 boards, none shared
Intelligence benchmarks for Qwen3.5-Flash and Solar Pro 4
BenchmarkQwen3.5-FlashSolar Pro 4Leader
AA Intelligence IndexNot measured28.2Only Solar Pro 4 measured
Epoch Capabilities Index143.5Not measuredOnly Qwen3.5-Flash measured
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index1 board, none shared
Agentic work benchmarks for Qwen3.5-Flash and Solar Pro 4
BenchmarkQwen3.5-FlashSolar Pro 4Leader
Design Arena: agents building web appsNot measured1105Only Solar Pro 4 measured
Neither model has a result on the other 41 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index12
Reasoning benchmarks for Qwen3.5-Flash and Solar Pro 4
BenchmarkQwen3.5-FlashSolar Pro 4Leader
GPQA Diamond82.8%Not measuredOnly Qwen3.5-Flash measured
MMMU Pro (Vals AI)81.9%Not measuredOnly Qwen3.5-Flash measured
GPQA Diamond (Artificial Analysis run)Not measured89.1%Only Solar Pro 4 measured
Humanity's Last Exam (Artificial Analysis run)Not measured29.8%Only Solar Pro 4 measured
GPQA Diamond (Epoch AI run)82.3%Not measuredOnly Qwen3.5-Flash measured
Chess puzzles14.0%Not measuredOnly Qwen3.5-Flash measured
Mystery game puzzles20.0%Not measuredOnly Qwen3.5-Flash measured
LMArena Text: hard prompts14031400Qwen3.5-Flash
LMArena Text: expert14071428Solar Pro 4
LMArena Text: hard prompts in English14091427Solar Pro 4
Neither model has a result on the other 13 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index02
Math benchmarks for Qwen3.5-Flash and Solar Pro 4
BenchmarkQwen3.5-FlashSolar Pro 4Leader
AIME92.5%Not measuredOnly Qwen3.5-Flash measured
OTIS Mock AIME84.4%Not measuredOnly Qwen3.5-Flash measured
FrontierMath, tiers 1 to 318.2%Not measuredOnly Qwen3.5-Flash measured
LMArena Text: math14071421Solar Pro 4
LMArena Text: mathematical work14131427Solar Pro 4
Neither model has a result on the other 9 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index40
Knowledge benchmarks for Qwen3.5-Flash and Solar Pro 4
BenchmarkQwen3.5-FlashSolar Pro 4Leader
MMLU Pro84.1%Not measuredOnly Qwen3.5-Flash measured
LegalBench (Vals AI)84.3%Not measuredOnly Qwen3.5-Flash measured
CaseLaw (Vals AI)56.0%Not measuredOnly Qwen3.5-Flash measured
CorpFin (Vals AI)63.6%Not measuredOnly Qwen3.5-Flash measured
TaxEval (Vals AI)72.2%Not measuredOnly Qwen3.5-Flash measured
MortgageTax (Vals AI)67.4%Not measuredOnly Qwen3.5-Flash measured
MedCode (Vals AI)33.0%Not measuredOnly Qwen3.5-Flash measured
SimpleQA Verified20.3%Not measuredOnly Qwen3.5-Flash measured
LMArena Text: science14151404Qwen3.5-Flash
LMArena Text: medicine and healthcare14071374Qwen3.5-Flash
LMArena Text: legal and government13981383Qwen3.5-Flash
LMArena Text: business and finance13941381Qwen3.5-Flash
Neither model has a result on the other 8 boards here
Web designDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
Web design benchmarks for Qwen3.5-Flash and Solar Pro 4
BenchmarkQwen3.5-FlashSolar Pro 4Leader
Design Arena: websitesNot measured1176Only Solar Pro 4 measured
Design Arena: UI componentsNot measured1147Only Solar Pro 4 measured
Design Arena: game devNot measured1169Only Solar Pro 4 measured
Design Arena: data vizNot measured1178Only Solar Pro 4 measured
Design Arena: 3DNot measured1178Only Solar Pro 4 measured
Design Arena: all code categoriesNot measured1182Only Solar Pro 4 measured
Neither model has a result on the other 3 boards here
GeneralLike-for-likePublic boards, shown as published, kept out of the index134
General benchmarks for Qwen3.5-Flash and Solar Pro 4
BenchmarkQwen3.5-FlashSolar Pro 4Leader
SAGE (Vals AI)42.5%Not measuredOnly Qwen3.5-Flash measured
MedScribe (Vals AI)70.6%Not measuredOnly Qwen3.5-Flash measured
Long context reasoning (AA-LCR)Not measured70.7%Only Solar Pro 4 measured
DTBench82.9%Not measuredOnly Qwen3.5-Flash measured
LMCA29.1%Not measuredOnly Qwen3.5-Flash measured
LMArena Text13971388Qwen3.5-Flash
LMArena Text: instruction following13741375Solar Pro 4
LMArena Text: creative writing13431317Qwen3.5-Flash
LMArena Text: English14041414Solar Pro 4
LMArena Text: non-English13851363Qwen3.5-Flash
LMArena Text: Chinese14451422Qwen3.5-Flash
LMArena Text: German13901358Qwen3.5-Flash
LMArena Text: Japanese13691320Qwen3.5-Flash
LMArena Text: Korean13441383Solar Pro 4
LMArena Text: French14131400Qwen3.5-Flash
LMArena Text: Spanish14001409Solar Pro 4
LMArena Text: Russian13801357Qwen3.5-Flash
LMArena Text: Polish13761304Qwen3.5-Flash
LMArena Text: multi-turn13931385Qwen3.5-Flash
LMArena Text: longer queries13921382Qwen3.5-Flash
LMArena Text: writing and language13691344Qwen3.5-Flash
LMArena Text: entertainment and media13471332Qwen3.5-Flash
Neither model has a result on the other 26 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Qwen3.5-Flash and Solar Pro 4
BenchmarkQwen3.5-FlashSolar Pro 4Leader
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

Qwen3.5-Flash$0.0002Fits in one request
Solar Pro 4$0.0004Fits in one request

Qwen3.5-Flash costs less

Repository review

50K input + 3K output tokens

Qwen3.5-Flash$0.0040Fits in one request
Solar Pro 4$0.0093Fits in one request

Qwen3.5-Flash costs less

Agent loop

200K input + 10K output tokens

Qwen3.5-Flash$0.016Fits in one request
Solar Pro 4$0.036Fits in one request

Qwen3.5-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 Qwen3.5-Flash and Solar Pro 4
SpecificationQwen3.5-FlashUpstage Solar Pro 4
MakerQwenUpstage
WeightsNo public weights listedNo public weights listed
ReleasedFebruary 25, 2026August 10, 2026
Context window1M524K
Input $/Mtok$0.065$0.15
Output $/Mtok$0.26$0.60
Coding index41.1Not benchmarked
Independent measurements behind it21
Cost per solved task$0.40Not computable
SourceOpenRouter listingOpenRouter listing

Questions

Is Qwen3.5-Flash better than Solar Pro 4 for coding?

Only Qwen3.5-Flash has a coding score, 41.1 on the Vibe Coding Index; Solar Pro 4 has none, so the two cannot be ranked on coding. Pick Solar Pro 4 for work measured by LMArena WebDev or LMArena Text: coding, where it leads.

Which is cheaper, Qwen3.5-Flash or Solar Pro 4?

Qwen3.5-Flash costs $0.065 per million input tokens and $0.26 per million output tokens; Solar Pro 4 costs $0.15 and $0.60. Cost per solved task is known for Qwen3.5-Flash only.

Which has the bigger context window, Qwen3.5-Flash or Solar Pro 4?

Qwen3.5-Flash, with 1M tokens against 524K.

How many benchmarks is the Qwen3.5-Flash vs Solar Pro 4 comparison based on?

32 benchmarks have a result for both models as of October 22, 2026. Qwen3.5-Flash's coding index rests on 2 independent benchmarks and Solar Pro 4's on 1. Where only one model has a result, the page says so instead of naming a winner.

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