Gemini 2.5 Flash vs Gemini 3.8 Flash
Gemini 3.8 Flash leads Gemini 2.5 Flash on the Artificial Analysis Intelligence Index, 40.9 to 15.5, and Gemini 2.5 Flash costs 1.5x less per output token ($2.50 vs $3.75 per million). Updated October 21, 2026; 57 benchmarks have a result for both.
Gemini 2.5 Flash or Gemini 3.8 Flash: which to pick
Only Gemini 3.8 Flash has a coding score, 61.6 on the Vibe Coding Index; Gemini 2.5 Flash has none, so the two cannot be ranked on coding.
Pick Gemini 2.5 Flash for output tokens 1.5x cheaper ($2.50 vs $3.75 per million) and a lower cost per solved task ($0.466 against $2.74).
- Shared results
- 57
- Gemini 2.5 Flash only
- 16
- Gemini 3.8 Flash only
- 71
- Like-for-like categories
- 8 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.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Only Gemini 3.8 Flash has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 40.9 against 15.5.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Gemini 3.8 Flash has a AA Agentic Index result, 40.2.
Directional only
Reasoning
GPQA Diamond
No call
Only Gemini 3.8 Flash has a GPQA Diamond result, 94.4%.
Directional only
Knowledge
MMLU Pro
No call
Only Gemini 3.8 Flash has a MMLU Pro result, 90.2%.
Directional only
Web design
Design Arena: websites
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 1300 against 1074.
Same board, both measured
General
Vals Index
No call
Only Gemini 3.8 Flash has a Vals Index result, 56.0%.
Directional only
Long documents
Listed context window
No call
Both take 1.05M tokens.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemini 2.5 Flash
Gemini 2.5 Flash $0.0015, Gemini 3.8 Flash $0.0026 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
Gemini 2.5 Flash
Gemini 2.5 Flash $0.466, Gemini 3.8 Flash $2.74.
Published attempt cost and pass rate
At a glance
- Coding index
- Gemini 2.5 Flash not benchmarked, Gemini 3.8 Flash 61.6 from 6 benchmarks.
- Widest category
- Web design, 32.9 points apart on average over 7 shared benchmarks.
- Widest single gap
- ARC-AGI-2: Gemini 2.5 Flash 2.5% against Gemini 3.8 Flash 89.2%, 86.6 points apart on a 0 to 100 scale.
- Output price
- Gemini 2.5 Flash $2.50 against Gemini 3.8 Flash $3.75 per million output tokens, 1.5x apart.
- Context window
- Both take 1.05M tokens.
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.
| Category | Gemini 2.5 Flash | Bars | Gemini 3.8 Flash | Ties |
|---|---|---|---|---|
| Coding | 0 | 2 | ||
| Intelligence | 0 | 2 | ||
| Agentic work | 0 | 1 | ||
| Reasoning | 0 | 9 | ||
| Math | 0 | 2 | ||
| Knowledge | 0 | 6 | ||
| Web design | 0 | 7 | ||
| General | 1 | 27 | ||
| All shared boards | 1 | 56 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index02
| Benchmark | Gemini 2.5 Flash | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| SWE-bench Verified | 28.7% | Not measured | Only Gemini 2.5 Flash measured |
| LiveBench coding | Not measured | 82.2% | Only Gemini 3.8 Flash measured |
| LMArena WebDev | Not measured | 1585 | Only Gemini 3.8 Flash measured |
| AA Coding Index | Not measured | 76.3 | Only Gemini 3.8 Flash measured |
| LiveCodeBench (Vals AI) | Not measured | 89.5% | Only Gemini 3.8 Flash measured |
| SWE-bench Verified (Vals AI) | Not measured | 80.0% | Only Gemini 3.8 Flash measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 19.7% | Only Gemini 3.8 Flash measured |
| Vibe Code Bench (Vals AI) | Not measured | 78.7% | Only Gemini 3.8 Flash measured |
| Code migration (Vals AI) | Not measured | 36.5% | Only Gemini 3.8 Flash measured |
| ProgramBench (Vals AI) | Not measured | 1.0% | Only Gemini 3.8 Flash measured |
| IOI (Vals AI) | Not measured | 56.9% | Only Gemini 3.8 Flash measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 81.3% | Only Gemini 3.8 Flash measured |
| SWE-bench Multimodal (Vals AI) | Not measured | 40.8% | Only Gemini 3.8 Flash measured |
| Vibe Code Bench 1-100 (Vals AI) | Not measured | 18.8% | Only Gemini 3.8 Flash measured |
| SkillsBench (Vals AI) | Not measured | 58.0% | Only Gemini 3.8 Flash measured |
| CyberBench (Vals AI) | Not measured | 43.8% | Only Gemini 3.8 Flash measured |
| LiveCodeBench (Artificial Analysis run) | 69.5% | Not measured | Only Gemini 2.5 Flash measured |
| SciCode | Not measured | 56.6% | Only Gemini 3.8 Flash measured |
| Terminal-Bench Hard (Artificial Analysis run) | 13.6% | Not measured | Only Gemini 2.5 Flash measured |
| Terminal-Bench | 17.1% | Not measured | Only Gemini 2.5 Flash measured |
| FrontierCode | Not measured | 41.2% | Only Gemini 3.8 Flash measured |
| FrontierSWE | Not measured | 19.6% | Only Gemini 3.8 Flash measured |
| WeirdML | Not measured | 84.8% | Only Gemini 3.8 Flash measured |
| ALE-Bench | Not measured | 1269.7 | Only Gemini 3.8 Flash measured |
| LMArena Text: coding | 1423 | 1508 | Gemini 3.8 Flash |
| LMArena Text: software and IT | 1425 | 1507 | Gemini 3.8 Flash |
| LMArena WebDev: React | Not measured | 1577 | Only Gemini 3.8 Flash measured |
| LMArena WebDev: HTML | Not measured | 1616 | Only Gemini 3.8 Flash measured |
| LMArena WebDev: from an image | Not measured | 1593 | Only Gemini 3.8 Flash measured |
| SciCode | Not measured | 12.3% | Only Gemini 3.8 Flash measured |
| Neither model has a result on the other 9 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | Gemini 2.5 Flash | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| AA Intelligence Index | 15.5 | 40.9 | Gemini 3.8 Flash |
| Epoch Capabilities Index | 142.9 | 157.4 | Gemini 3.8 Flash |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Gemini 2.5 Flash | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| AA Agentic Index | Not measured | 40.2 | Only Gemini 3.8 Flash measured |
| Design Arena: agents building web apps | Not measured | 1238 | Only Gemini 3.8 Flash measured |
| Design Arena: agents building full-stack apps | Not measured | 1244 | Only Gemini 3.8 Flash measured |
| Design Arena: agents building mobile apps | Not measured | 1236 | Only Gemini 3.8 Flash measured |
| Design Arena: agents building Android apps | Not measured | 1074 | Only Gemini 3.8 Flash measured |
| Design Arena: agents building Godot games | Not measured | 1273 | Only Gemini 3.8 Flash measured |
| Design Arena: PowerPoint slides | Not measured | 1177 | Only Gemini 3.8 Flash measured |
| Design Arena: spreadsheets | Not measured | 1056 | Only Gemini 3.8 Flash measured |
| LiveBench research | Not measured | 79.1% | Only Gemini 3.8 Flash measured |
| LiveBench browser | Not measured | 64.0% | Only Gemini 3.8 Flash measured |
| LiveBench long agentic | Not measured | 30.1% | Only Gemini 3.8 Flash measured |
| SREBench (Vals AI) | Not measured | 11.1% | Only Gemini 3.8 Flash measured |
| Finance Agent (Vals AI) | Not measured | 61.4% | Only Gemini 3.8 Flash measured |
| Tax Agent Bench (Vals AI) | Not measured | 32.1% | Only Gemini 3.8 Flash measured |
| Legal Research Bench (Vals AI) | Not measured | 38.9% | Only Gemini 3.8 Flash measured |
| Harvey's Legal Agent Benchmark (Vals AI) | Not measured | 12.1% | Only Gemini 3.8 Flash measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 72.2% | Only Gemini 3.8 Flash measured |
| BioMysteryBench (Vals AI) | Not measured | 62.2% | Only Gemini 3.8 Flash measured |
| Terminal-Bench-Science (Vals AI) | Not measured | 8.6% | Only Gemini 3.8 Flash measured |
| Vals Science Index | Not measured | 35.8% | Only Gemini 3.8 Flash measured |
| Time Horizon Index (Vals AI) | Not measured | 18.8% | Only Gemini 3.8 Flash measured |
| CUA-bench (Vals AI) | Not measured | 4.2% | Only Gemini 3.8 Flash measured |
| τ²-Bench Telecom | 31.6% | Not measured | Only Gemini 2.5 Flash measured |
| APEX-Agents | Not measured | 64.3% | Only Gemini 3.8 Flash measured |
| Remote Labor Index | Not measured | 5.8% | Only Gemini 3.8 Flash measured |
| BALROG | 33.5% | Not measured | Only Gemini 2.5 Flash measured |
| Vending-Bench 2 | $549 | $5,094 | Gemini 3.8 Flash |
| Berkeley Function Calling Leaderboard (BFCL) | 56.2% | Not measured | Only Gemini 2.5 Flash measured |
| BrowseComp-Plus | 39.9% | Not measured | Only Gemini 2.5 Flash measured |
| Neither model has a result on the other 12 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index09
| Benchmark | Gemini 2.5 Flash | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 94.4% | Only Gemini 3.8 Flash measured |
| LiveBench reasoning | Not measured | 89.3% | Only Gemini 3.8 Flash measured |
| MysteryMechanism (Vals AI) | Not measured | 36.5% | Only Gemini 3.8 Flash measured |
| MMMU Pro (Vals AI) | Not measured | 89.1% | Only Gemini 3.8 Flash measured |
| GPQA Diamond (Artificial Analysis run) | 79.0% | 95.3% | Gemini 3.8 Flash |
| Humanity's Last Exam (Artificial Analysis run) | 12.1% | 47.8% | Gemini 3.8 Flash |
| GPQA Diamond (Epoch AI run) | Not measured | 95.4% | Only Gemini 3.8 Flash measured |
| ARC-AGI | 33.3% | 98.5% | Gemini 3.8 Flash |
| ARC-AGI-2 | 2.5% | 89.2% | Gemini 3.8 Flash |
| SimpleBench | 41.2% | Not measured | Only Gemini 2.5 Flash measured |
| Chess puzzles | Not measured | 58.0% | Only Gemini 3.8 Flash measured |
| Mystery game puzzles | Not measured | 47.0% | Only Gemini 3.8 Flash measured |
| LMArena Text: hard prompts | 1422 | 1509 | Gemini 3.8 Flash |
| LMArena Text: expert | 1426 | 1526 | Gemini 3.8 Flash |
| LMArena Text: hard prompts in English | 1420 | 1504 | Gemini 3.8 Flash |
| LMArena Vision: diagrams | 1245 | 1345 | Gemini 3.8 Flash |
| LMArena Vision: homework | 1244 | 1351 | Gemini 3.8 Flash |
| Kagi LLM Benchmark | 56.8% | Not measured | Only Gemini 2.5 Flash measured |
| Neither model has a result on the other 4 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index02
| Benchmark | Gemini 2.5 Flash | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| AA Math Index | 73.3 | Not measured | Only Gemini 2.5 Flash measured |
| AIME 2025 (Artificial Analysis run) | 73.3% | Not measured | Only Gemini 2.5 Flash measured |
| OTIS Mock AIME | Not measured | 98.9% | Only Gemini 3.8 Flash measured |
| FrontierMath, tiers 1 to 3 | Not measured | 68.4% | Only Gemini 3.8 Flash measured |
| FrontierMath, tier 4 | Not measured | 22.0% | Only Gemini 3.8 Flash measured |
| ProofBench | Not measured | 48.0% | Only Gemini 3.8 Flash measured |
| LMArena Text: math | 1411 | 1532 | Gemini 3.8 Flash |
| LMArena Text: mathematical work | 1422 | 1519 | Gemini 3.8 Flash |
| Neither model has a result on the other 5 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index06
| Benchmark | Gemini 2.5 Flash | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 90.2% | Only Gemini 3.8 Flash measured |
| LegalBench (Vals AI) | Not measured | 87.0% | Only Gemini 3.8 Flash measured |
| TaxEval (Vals AI) | Not measured | 74.5% | Only Gemini 3.8 Flash measured |
| MortgageTax (Vals AI) | Not measured | 65.3% | Only Gemini 3.8 Flash measured |
| MedCode (Vals AI) | 40.4% | 48.1% | Gemini 3.8 Flash |
| MMLU Pro (Artificial Analysis run) | 83.2% | Not measured | Only Gemini 2.5 Flash measured |
| SimpleQA Verified | Not measured | 69.7% | Only Gemini 3.8 Flash measured |
| LMArena Text: science | 1433 | 1523 | Gemini 3.8 Flash |
| LMArena Text: medicine and healthcare | 1428 | 1508 | Gemini 3.8 Flash |
| LMArena Text: legal and government | 1430 | 1497 | Gemini 3.8 Flash |
| LMArena Text: business and finance | 1404 | 1479 | Gemini 3.8 Flash |
| FACTS Benchmark Suite | 47.2% | 69.4% | Gemini 3.8 Flash |
| Neither model has a result on the other 6 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index07
| Benchmark | Gemini 2.5 Flash | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| Design Arena: websites | 1074 | 1300 | Gemini 3.8 Flash |
| Design Arena: UI components | 1005 | 1319 | Gemini 3.8 Flash |
| Design Arena: game dev | 1005 | 1305 | Gemini 3.8 Flash |
| Design Arena: data viz | 1060 | 1269 | Gemini 3.8 Flash |
| Design Arena: 3D | 1021 | 1295 | Gemini 3.8 Flash |
| Design Arena: all code categories | 1059 | 1304 | Gemini 3.8 Flash |
| Design Arena: SVG | 1020 | 1295 | Gemini 3.8 Flash |
| Design Arena: ASCII art | Not measured | 1265 | Only Gemini 3.8 Flash measured |
| LiveBench design | Not measured | 72.7% | Only Gemini 3.8 Flash measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index127
| Benchmark | Gemini 2.5 Flash | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| Vals Index | Not measured | 56.0% | Only Gemini 3.8 Flash measured |
| LiveBench data analysis | Not measured | 54.0% | Only Gemini 3.8 Flash measured |
| Public Benefits Bench (Vals AI) | Not measured | 65.3% | Only Gemini 3.8 Flash measured |
| SAGE (Vals AI) | 44.8% | 35.1% | Gemini 2.5 Flash |
| MedScribe (Vals AI) | 83.0% | 84.5% | Gemini 3.8 Flash |
| IFBench | 50.3% | Not measured | Only Gemini 2.5 Flash measured |
| Long context reasoning (AA-LCR) | 65.3% | 84.0% | Gemini 3.8 Flash |
| DTBench | 76.5% | 95.7% | Gemini 3.8 Flash |
| LMCA | 27.5% | 52.9% | Gemini 3.8 Flash |
| Surface Evolver Bench | Not measured | 76.9% | Only Gemini 3.8 Flash measured |
| Furniture assembly | Not measured | 31.7% | Only Gemini 3.8 Flash measured |
| LMArena Text | 1417 | 1499 | Gemini 3.8 Flash |
| LMArena Text: instruction following | 1405 | 1492 | Gemini 3.8 Flash |
| LMArena Text: creative writing | 1400 | 1488 | Gemini 3.8 Flash |
| LMArena Vision | 1235 | 1315 | Gemini 3.8 Flash |
| LMArena Text: English | 1418 | 1498 | Gemini 3.8 Flash |
| LMArena Text: non-English | 1409 | 1491 | Gemini 3.8 Flash |
| LMArena Text: Chinese | 1449 | 1553 | Gemini 3.8 Flash |
| LMArena Text: German | 1417 | 1501 | Gemini 3.8 Flash |
| LMArena Text: Japanese | 1396 | 1507 | Gemini 3.8 Flash |
| LMArena Text: Korean | 1385 | 1464 | Gemini 3.8 Flash |
| LMArena Text: French | 1432 | 1496 | Gemini 3.8 Flash |
| LMArena Text: Spanish | 1422 | 1487 | Gemini 3.8 Flash |
| LMArena Text: Russian | 1415 | 1514 | Gemini 3.8 Flash |
| LMArena Text: Polish | 1413 | 1497 | Gemini 3.8 Flash |
| LMArena Text: multi-turn | 1408 | 1503 | Gemini 3.8 Flash |
| LMArena Text: longer queries | 1419 | 1507 | Gemini 3.8 Flash |
| LMArena Text: writing and language | 1405 | 1494 | Gemini 3.8 Flash |
| LMArena Text: entertainment and media | 1393 | 1480 | Gemini 3.8 Flash |
| LMArena Vision: English | 1239 | 1318 | Gemini 3.8 Flash |
| LMArena Vision: Chinese | 1284 | 1416 | Gemini 3.8 Flash |
| LMArena Vision: reading text | 1237 | 1333 | Gemini 3.8 Flash |
| LMArena Vision: humor | 1225 | 1321 | Gemini 3.8 Flash |
| LMArena Vision: captioning | 1277 | Not measured | Only Gemini 2.5 Flash measured |
| LMArena Vision: recognizing things | 1252 | Not measured | Only Gemini 2.5 Flash measured |
| LMArena Vision: creative writing | 1241 | 1299 | Gemini 3.8 Flash |
| Neither model has a result on the other 10 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Gemini 2.5 Flash | Gemini 3.8 Flash | Leader |
|---|---|---|---|
| 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
Gemini 2.5 Flash costs less
Repository review
50K input + 3K output tokens
Gemini 2.5 Flash costs less
Agent loop
200K input + 10K output tokens
Gemini 2.5 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.
| Specification | Google Gemini 2.5 Flash | Google Gemini 3.8 Flash |
|---|---|---|
| Maker | ||
| Weights | No public weights listed | No public weights listed |
| Released | June 17, 2025 | September 2, 2026 |
| Context window | 1.05M | 1.05M |
| Input $/Mtok | $0.30 | $0.75 |
| Output $/Mtok | $2.50 | $3.75 |
| Coding index | Not benchmarked | 61.6 |
| Independent measurements behind it | 0 | 6 |
| Cost per solved task | $0.466 | $2.74 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Gemini 2.5 Flash better than Gemini 3.8 Flash for coding?
Only Gemini 3.8 Flash has a coding score, 61.6 on the Vibe Coding Index; Gemini 2.5 Flash has none, so the two cannot be ranked on coding. Pick Gemini 2.5 Flash for output tokens 1.5x cheaper ($2.50 vs $3.75 per million) and a lower cost per solved task ($0.466 against $2.74).
Which is cheaper, Gemini 2.5 Flash or Gemini 3.8 Flash?
Gemini 2.5 Flash costs $0.30 per million input tokens and $2.50 per million output tokens; Gemini 3.8 Flash costs $0.75 and $3.75. Per solved SWE-bench Verified task, Gemini 2.5 Flash costs $0.466 and Gemini 3.8 Flash $2.74.
Which has the bigger context window, Gemini 2.5 Flash or Gemini 3.8 Flash?
Neither: both take 1.05M tokens.
How many benchmarks is the Gemini 2.5 Flash vs Gemini 3.8 Flash comparison based on?
57 benchmarks have a result for both models as of October 21, 2026. Gemini 2.5 Flash's coding index rests on 0 independent benchmarks and Gemini 3.8 Flash's on 6. Where only one model has a result, the page says so instead of naming a winner.