Qwen3.5 Plus 2026-04-20 vs Qwen3.8 Flash
Qwen3.8 Flash costs 3.8x less per output token than Qwen3.5 Plus 2026-04-20 ($0.47 vs $1.80 per million). Updated October 22, 2026; no benchmark has tested both models yet.
- Coding
- 39.5
- Overall
- No data
- Output $/M
- $1.80
- Coding
- No data
- Overall
- No data
- Output $/M
- $0.47
Qwen3.5 Plus 2026-04-20 or Qwen3.8 Flash: which to pick
Only Qwen3.5 Plus 2026-04-20 has a coding score, 39.5 on the Vibe Coding Index; Qwen3.8 Flash has none, so the two cannot be ranked on coding.
Pick Qwen3.8 Flash for output tokens 3.8x cheaper ($0.47 vs $1.80 per million).
No benchmark has tested both yet. Qwen3.5 Plus 2026-04-20 has results on LiveCodeBench (Vals AI), SWE-bench Verified (Vals AI) and Vibe Code Bench (Vals AI); Qwen3.8 Flash on LiveBench coding, LiveBench research and LiveBench browser. Compare them on price and context instead.
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.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Only Qwen3.5 Plus 2026-04-20 has a coding score, so no call is made.
One side not measured
Reasoning
GPQA Diamond
No call
Only Qwen3.5 Plus 2026-04-20 has a GPQA Diamond result, 87.4%.
Directional only
Math
AIME
No call
Only Qwen3.5 Plus 2026-04-20 has a AIME result, 86.0%.
Directional only
Knowledge
MMLU Pro
No call
Only Qwen3.5 Plus 2026-04-20 has a MMLU Pro result, 87.2%.
Directional only
Long documents
Listed context window
No call
Both take 1M tokens.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Qwen3.8 Flash
Qwen3.5 Plus 2026-04-20 $0.0012, Qwen3.8 Flash $0.0004 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Qwen3.5 Plus 2026-04-20 has the number, $1.35.
Directional only
At a glance
- Coding index
- Qwen3.5 Plus 2026-04-20 39.5 from 2 benchmarks, Qwen3.8 Flash not benchmarked.
- Widest category
- None yet: no category has been tested on both models.
- Widest single gap
- None yet: no benchmark has tested both models.
- Output price
- Qwen3.5 Plus 2026-04-20 $1.80 against Qwen3.8 Flash $0.47 per million output tokens, 3.8x apart.
- Context window
- Both take 1M tokens.
Benchmark by benchmark
Every board either model has a result on, a category to a fold; bars are each result on a 0 to 100 scale. Only one model is measured on each, so no row names a leader.
CodingDirectional onlySix of these boards feed the Vibe Coding Index5 boards measured
| Benchmark | Qwen3.5 Plus 2026-04-20 | Qwen3.8 Flash | Leader |
|---|---|---|---|
| LiveBench coding | Not measured | 87.4% | Only Qwen3.8 Flash measured |
| LiveCodeBench (Vals AI) | 85.3% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| SWE-bench Verified (Vals AI) | 71.2% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Vibe Code Bench (Vals AI) | 15.7% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| ALE-Bench | 608.9 | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Neither model has a result on the other 38 boards here | |||
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index1 board measured
| Benchmark | Qwen3.5 Plus 2026-04-20 | Qwen3.8 Flash | Leader |
|---|---|---|---|
| Epoch Capabilities Index | 146.2 | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Neither model has a result on the other 1 board here | |||
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index4 boards measured
| Benchmark | Qwen3.5 Plus 2026-04-20 | Qwen3.8 Flash | Leader |
|---|---|---|---|
| LiveBench research | Not measured | 74.6% | Only Qwen3.8 Flash measured |
| LiveBench browser | Not measured | 48.0% | Only Qwen3.8 Flash measured |
| LiveBench long agentic | Not measured | 37.1% | Only Qwen3.8 Flash measured |
| Vending-Bench 2 | $1 | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Neither model has a result on the other 38 boards here | |||
ReasoningDirectional onlyPublic boards, shown as published, kept out of the index6 boards measured
| Benchmark | Qwen3.5 Plus 2026-04-20 | Qwen3.8 Flash | Leader |
|---|---|---|---|
| GPQA Diamond | 87.4% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| LiveBench reasoning | Not measured | 87.4% | Only Qwen3.8 Flash measured |
| MMMU Pro (Vals AI) | 22.8% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| GPQA Diamond (Epoch AI run) | 84.8% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Chess puzzles | 8.0% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Mystery game puzzles | 17.0% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Neither model has a result on the other 17 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index2 boards measured
| Benchmark | Qwen3.5 Plus 2026-04-20 | Qwen3.8 Flash | Leader |
|---|---|---|---|
| AIME | 86.0% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| OTIS Mock AIME | 86.7% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Neither model has a result on the other 12 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index7 boards measured
| Benchmark | Qwen3.5 Plus 2026-04-20 | Qwen3.8 Flash | Leader |
|---|---|---|---|
| MMLU Pro | 87.2% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| LegalBench (Vals AI) | 85.1% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| CaseLaw (Vals AI) | 59.7% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| CorpFin (Vals AI) | 65.3% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| MortgageTax (Vals AI) | 60.8% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| MedQA (Vals AI) | 95.2% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| SimpleQA Verified | 25.4% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Neither model has a result on the other 13 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index1 board measured
| Benchmark | Qwen3.5 Plus 2026-04-20 | Qwen3.8 Flash | Leader |
|---|---|---|---|
| LiveBench design | Not measured | 72.8% | Only Qwen3.8 Flash measured |
| Neither model has a result on the other 8 boards here | |||
GeneralDirectional onlyPublic boards, shown as published, kept out of the index6 boards measured
| Benchmark | Qwen3.5 Plus 2026-04-20 | Qwen3.8 Flash | Leader |
|---|---|---|---|
| LiveBench data analysis | Not measured | 74.2% | Only Qwen3.8 Flash measured |
| SAGE (Vals AI) | 30.4% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| DTBench | 80.5% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| LMCA | 36.4% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| CL-bench | 19.8% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| CL-bench Life | 12.4% | Not measured | Only Qwen3.5 Plus 2026-04-20 measured |
| Neither model has a result on the other 42 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
Qwen3.8 Flash costs less
Repository review
50K input + 3K output tokens
Qwen3.8 Flash costs less
Agent loop
200K input + 10K output tokens
Qwen3.8 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.
| Specification | Qwen3.5 Plus 2026-04-20 | Qwen3.8 Flash |
|---|---|---|
| Maker | Qwen | Qwen |
| Weights | No public weights listed | Open weights |
| Released | April 27, 2026 | August 26, 2026 |
| Context window | 1M | 1M |
| Input $/Mtok | $0.30 | $0.15 |
| Output $/Mtok | $1.80 | $0.47 |
| Coding index | 39.5 | Not benchmarked |
| Independent measurements behind it | 2 | 1 |
| Cost per solved task | $1.35 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Qwen3.5 Plus 2026-04-20 better than Qwen3.8 Flash for coding?
Only Qwen3.5 Plus 2026-04-20 has a coding score, 39.5 on the Vibe Coding Index; Qwen3.8 Flash has none, so the two cannot be ranked on coding. Pick Qwen3.8 Flash for output tokens 3.8x cheaper ($0.47 vs $1.80 per million).
Which is cheaper, Qwen3.5 Plus 2026-04-20 or Qwen3.8 Flash?
Qwen3.5 Plus 2026-04-20 costs $0.30 per million input tokens and $1.80 per million output tokens; Qwen3.8 Flash costs $0.15 and $0.47. Cost per solved task is known for Qwen3.5 Plus 2026-04-20 only.
Which has the bigger context window, Qwen3.5 Plus 2026-04-20 or Qwen3.8 Flash?
Neither: both take 1M tokens.
Has any benchmark tested both Qwen3.5 Plus 2026-04-20 and Qwen3.8 Flash?
No benchmark has tested both yet. Qwen3.5 Plus 2026-04-20 has results on LiveCodeBench (Vals AI), SWE-bench Verified (Vals AI) and Vibe Code Bench (Vals AI); Qwen3.8 Flash on LiveBench coding, LiveBench research and LiveBench browser. Compare them on price and context instead. Data as of October 22, 2026.