Claude Opus 4.5 vs Gemini 3.8 Flash

Gemini 3.8 Flash leads Claude Opus 4.5 on coding, 61.6 to 44.0 on the Vibe Coding Index, and Gemini 3.8 Flash costs 6.7x less per output token ($3.75 vs $25.00 per million). Updated October 21, 2026; 77 benchmarks have a result for both.

Replace Claude Opus 4.5 Replace Gemini 3.8 Flash

Claude Opus 4.5Anthropic

Coding: 44.0
Overall: 55.7
Output $/M: $25.00

Gemini 3.8 FlashGoogle

Coding: 61.6
Overall: 69.0
Output $/M: $3.75

vs boards won of 77 shared

Claude Opus 4.5 or Gemini 3.8 Flash: which to pick

Pick Gemini 3.8 Flash for coding: it scores 61.6 on the Vibe Coding Index against 44.0 for Claude Opus 4.5.

Pick Claude Opus 4.5 for a lower cost per solved task ($1.37 against $2.74) and work measured by Design Arena: agents building Android apps or TaxEval (Vals AI), where it leads.

Model AClaude Opus 4.5Anthropic44.0/1003 independent benchmarks$1.37 per solved task Model BGemini 3.8 FlashGoogle61.6/1006 independent benchmarks$2.74 per solved task

773151

Shared results: 77
Claude Opus 4.5 only: 31
Gemini 3.8 Flash only: 51
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
Gemini 3.8 Flash
Gemini 3.8 Flash scores 61.6 against 44.0.
3 and 6 benchmarks behind the scores
Intelligence
AA Intelligence Index
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 40.9 against 29.1.
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
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 94.4% against 85.9%.
Same board, both measured
Math
AIME
No call
Only Claude Opus 4.5 has a AIME result, 95.4%.
Directional only
Knowledge
MMLU Pro
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 90.2% against 87.3%.
Same board, both measured
Web design
Design Arena: websites
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 1300 against 1247.
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
Gemini 3.8 Flash
Gemini 3.8 Flash takes 1.05M tokens against 200K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemini 3.8 Flash
Claude Opus 4.5 $0.018, Gemini 3.8 Flash $0.0026 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
Claude Opus 4.5
Claude Opus 4.5 $1.37, Gemini 3.8 Flash $2.74.
Published attempt cost and pass rate

At a glance

Coding index: Claude Opus 4.5 44.0 from 3 benchmarks, Gemini 3.8 Flash 61.6 from 6 benchmarks.
Widest category: Reasoning, 17.1 points apart on average over 12 shared benchmarks.
Widest single gap: Vibe Code Bench (Vals AI): Claude Opus 4.5 20.6% against Gemini 3.8 Flash 78.7%, 58.0 points apart on a 0 to 100 scale.
Output price: Claude Opus 4.5 $25.00 against Gemini 3.8 Flash $3.75 per million output tokens, 6.7x apart.
Context window: Claude Opus 4.5 takes 200K tokens, Gemini 3.8 Flash 1.05M.

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
Category	Claude Opus 4.5	Gemini 3.8 Flash
Coding	0	9
Intelligence	0	2
Agentic work	1	5
Reasoning	0	12
Math	0	6
Knowledge	3	8
Web design	0	8
General	2	21
All shared boards	6	71

CodingLike-for-likeSix of these boards feed the Vibe Coding Index09

Coding benchmarks for Claude Opus 4.5 and Gemini 3.8 Flash
Benchmark	Claude Opus 4.5	Gemini 3.8 Flash	Leader
SWE-bench Verified	79.2%	Not measured	Only Claude Opus 4.5 measured
SWE-bench (full test set)	52.6%	Not measured	Only Claude Opus 4.5 measured
SWE-bench Multilingual	70.7%	Not measured	Only Claude Opus 4.5 measured
LiveBench coding	Not measured	82.2%	Only Gemini 3.8 Flash measured
LMArena WebDev	1494	1585	Gemini 3.8 Flash
AA Coding Index	Not measured	76.3	Only Gemini 3.8 Flash measured
LiveCodeBench (Vals AI)	83.7%	89.5%	Gemini 3.8 Flash
SWE-bench Verified (Vals AI)	76.4%	80.0%	Gemini 3.8 Flash
Terminal-Bench 4 (Vals AI)	Not measured	19.7%	Only Gemini 3.8 Flash measured
Vibe Code Bench (Vals AI)	20.6%	78.7%	Gemini 3.8 Flash
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)	87.1%	Not measured	Only Claude Opus 4.5 measured
SciCode	Not measured	56.6%	Only Gemini 3.8 Flash measured
Terminal-Bench Hard (Artificial Analysis run)	47.0%	Not measured	Only Claude Opus 4.5 measured
Terminal-Bench	63.1%	Not measured	Only Claude Opus 4.5 measured
FrontierCode	Not measured	41.2%	Only Gemini 3.8 Flash measured
FrontierSWE	Not measured	19.6%	Only Gemini 3.8 Flash measured
GSO-Bench	26.5%	Not measured	Only Claude Opus 4.5 measured
WeirdML	63.7%	84.8%	Gemini 3.8 Flash
Cybench	82.0%	Not measured	Only Claude Opus 4.5 measured
ALE-Bench	Not measured	1269.7	Only Gemini 3.8 Flash measured
LMArena Text: coding	1503	1508	Gemini 3.8 Flash
LMArena Text: software and IT	1483	1507	Gemini 3.8 Flash
LMArena WebDev: React	1478	1577	Gemini 3.8 Flash
LMArena WebDev: HTML	1510	1616	Gemini 3.8 Flash
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 5 boards here

IntelligenceLike-for-likePublic boards, shown as published, kept out of the index02

Intelligence benchmarks for Claude Opus 4.5 and Gemini 3.8 Flash
Benchmark	Claude Opus 4.5	Gemini 3.8 Flash	Leader
AA Intelligence Index	29.1	40.9	Gemini 3.8 Flash
Epoch Capabilities Index	150.1	157.4	Gemini 3.8 Flash

Agentic workLike-for-likePublic boards, shown as published, kept out of the index15

Agentic work benchmarks for Claude Opus 4.5 and Gemini 3.8 Flash
Benchmark	Claude Opus 4.5	Gemini 3.8 Flash	Leader
AA Agentic Index	Not measured	40.2	Only Gemini 3.8 Flash measured
Design Arena: agents building web apps	1159	1238	Gemini 3.8 Flash
Design Arena: agents building full-stack apps	1156	1244	Gemini 3.8 Flash
Design Arena: agents building mobile apps	1189	1236	Gemini 3.8 Flash
Design Arena: agents building Android apps	1175	1074	Claude Opus 4.5
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	89.5%	Not measured	Only Claude Opus 4.5 measured
APEX-Agents	Not measured	64.3%	Only Gemini 3.8 Flash measured
METR time horizons	75.0%	Not measured	Only Claude Opus 4.5 measured
Remote Labor Index	3.8%	5.8%	Gemini 3.8 Flash
GDPval	45.5%	Not measured	Only Claude Opus 4.5 measured
BALROG	43.5%	Not measured	Only Claude Opus 4.5 measured
DeepResearch Bench	54.8%	Not measured	Only Claude Opus 4.5 measured
OSWorld	66.3%	Not measured	Only Claude Opus 4.5 measured
Vending-Bench 2	$4,967	$5,094	Gemini 3.8 Flash
Berkeley Function Calling Leaderboard (BFCL)	77.5%	Not measured	Only Claude Opus 4.5 measured
Neither model has a result on the other 9 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index012

Reasoning benchmarks for Claude Opus 4.5 and Gemini 3.8 Flash
Benchmark	Claude Opus 4.5	Gemini 3.8 Flash	Leader
GPQA Diamond	85.9%	94.4%	Gemini 3.8 Flash
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)	83.0%	89.1%	Gemini 3.8 Flash
GPQA Diamond (Artificial Analysis run)	86.6%	95.3%	Gemini 3.8 Flash
Humanity's Last Exam (Artificial Analysis run)	30.1%	47.8%	Gemini 3.8 Flash
GPQA Diamond (Epoch AI run)	86.0%	95.4%	Gemini 3.8 Flash
ARC-AGI	80.0%	98.5%	Gemini 3.8 Flash
ARC-AGI-2	37.6%	89.2%	Gemini 3.8 Flash
SimpleBench	62.0%	Not measured	Only Claude Opus 4.5 measured
Chess puzzles	14.0%	58.0%	Gemini 3.8 Flash
Mystery game puzzles	22.0%	47.0%	Gemini 3.8 Flash
EBR-bench	14.3%	Not measured	Only Claude Opus 4.5 measured
VPCT	40.0%	Not measured	Only Claude Opus 4.5 measured
LMArena Text: hard prompts	1476	1509	Gemini 3.8 Flash
LMArena Text: expert	1487	1526	Gemini 3.8 Flash
LMArena Text: hard prompts in English	1482	1504	Gemini 3.8 Flash
LMArena Vision: diagrams	Not measured	1345	Only Gemini 3.8 Flash measured
LMArena Vision: homework	Not measured	1351	Only Gemini 3.8 Flash measured
Kagi LLM Benchmark	80.2%	Not measured	Only Claude Opus 4.5 measured
Neither model has a result on the other 2 boards here

MathLike-for-likePublic boards, shown as published, kept out of the index06

Math benchmarks for Claude Opus 4.5 and Gemini 3.8 Flash
Benchmark	Claude Opus 4.5	Gemini 3.8 Flash	Leader
AIME	95.4%	Not measured	Only Claude Opus 4.5 measured
MGSM (Vals AI)	95.2%	Not measured	Only Claude Opus 4.5 measured
AA Math Index	91.3	Not measured	Only Claude Opus 4.5 measured
AIME 2025 (Artificial Analysis run)	91.3%	Not measured	Only Claude Opus 4.5 measured
OTIS Mock AIME	86.1%	98.9%	Gemini 3.8 Flash
FrontierMath, tiers 1 to 3	34.4%	68.4%	Gemini 3.8 Flash
FrontierMath, tier 4	4.9%	22.0%	Gemini 3.8 Flash
ProofBench	36.0%	48.0%	Gemini 3.8 Flash
LMArena Text: math	1463	1532	Gemini 3.8 Flash
LMArena Text: mathematical work	1468	1519	Gemini 3.8 Flash
Neither model has a result on the other 3 boards here

KnowledgeLike-for-likePublic boards, shown as published, kept out of the index38

Knowledge benchmarks for Claude Opus 4.5 and Gemini 3.8 Flash
Benchmark	Claude Opus 4.5	Gemini 3.8 Flash	Leader
MMLU Pro	87.3%	90.2%	Gemini 3.8 Flash
LegalBench (Vals AI)	84.6%	87.0%	Gemini 3.8 Flash
CaseLaw (Vals AI)	62.6%	Not measured	Only Claude Opus 4.5 measured
CorpFin (Vals AI)	65.1%	Not measured	Only Claude Opus 4.5 measured
TaxEval (Vals AI)	74.9%	74.5%	Claude Opus 4.5
MortgageTax (Vals AI)	68.7%	65.3%	Claude Opus 4.5
MedQA (Vals AI)	95.9%	Not measured	Only Claude Opus 4.5 measured
MedCode (Vals AI)	49.2%	48.1%	Claude Opus 4.5
MMLU Pro (Artificial Analysis run)	89.5%	Not measured	Only Claude Opus 4.5 measured
SimpleQA Verified	45.7%	69.7%	Gemini 3.8 Flash
GeoBench	75.0%	Not measured	Only Claude Opus 4.5 measured
LMArena Text: science	1454	1523	Gemini 3.8 Flash
LMArena Text: medicine and healthcare	1444	1508	Gemini 3.8 Flash
LMArena Text: legal and government	1459	1497	Gemini 3.8 Flash
LMArena Text: business and finance	1448	1479	Gemini 3.8 Flash
FACTS Benchmark Suite	43.9%	69.4%	Gemini 3.8 Flash
Neither model has a result on the other 2 boards here

Web designLike-for-likePublic boards, shown as published, kept out of the index08

Web design benchmarks for Claude Opus 4.5 and Gemini 3.8 Flash
Benchmark	Claude Opus 4.5	Gemini 3.8 Flash	Leader
Design Arena: websites	1247	1300	Gemini 3.8 Flash
Design Arena: UI components	1238	1319	Gemini 3.8 Flash
Design Arena: game dev	1229	1305	Gemini 3.8 Flash
Design Arena: data viz	1243	1269	Gemini 3.8 Flash
Design Arena: 3D	1214	1295	Gemini 3.8 Flash
Design Arena: all code categories	1242	1304	Gemini 3.8 Flash
Design Arena: SVG	1181	1295	Gemini 3.8 Flash
Design Arena: ASCII art	1190	1265	Gemini 3.8 Flash
LiveBench design	Not measured	72.7%	Only Gemini 3.8 Flash measured

GeneralLike-for-likePublic boards, shown as published, kept out of the index221

General benchmarks for Claude Opus 4.5 and Gemini 3.8 Flash
Benchmark	Claude Opus 4.5	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)	52.1%	35.1%	Claude Opus 4.5
MedScribe (Vals AI)	85.3%	84.5%	Claude Opus 4.5
IFBench	58.0%	Not measured	Only Claude Opus 4.5 measured
Long context reasoning (AA-LCR)	77.3%	84.0%	Gemini 3.8 Flash
DTBench	89.9%	95.7%	Gemini 3.8 Flash
LMCA	44.5%	52.9%	Gemini 3.8 Flash
CL-bench	21.1%	Not measured	Only Claude Opus 4.5 measured
Surface Evolver Bench	Not measured	76.9%	Only Gemini 3.8 Flash measured
Furniture assembly	28.3%	31.7%	Gemini 3.8 Flash
LMArena Text	1451	1499	Gemini 3.8 Flash
LMArena Text: instruction following	1478	1492	Gemini 3.8 Flash
LMArena Text: creative writing	1445	1488	Gemini 3.8 Flash
LMArena Vision	Not measured	1315	Only Gemini 3.8 Flash measured
LMArena Text: English	1461	1498	Gemini 3.8 Flash
LMArena Text: non-English	1438	1491	Gemini 3.8 Flash
LMArena Text: Chinese	1470	1553	Gemini 3.8 Flash
LMArena Text: German	1449	1501	Gemini 3.8 Flash
LMArena Text: Japanese	1417	1507	Gemini 3.8 Flash
LMArena Text: Korean	1424	1464	Gemini 3.8 Flash
LMArena Text: French	1471	1496	Gemini 3.8 Flash
LMArena Text: Spanish	1457	1487	Gemini 3.8 Flash
LMArena Text: Russian	1447	1514	Gemini 3.8 Flash
LMArena Text: Polish	1439	1497	Gemini 3.8 Flash
LMArena Text: multi-turn	1466	1503	Gemini 3.8 Flash
LMArena Text: longer queries	1479	1507	Gemini 3.8 Flash
LMArena Text: writing and language	1452	1494	Gemini 3.8 Flash
LMArena Text: entertainment and media	1434	1480	Gemini 3.8 Flash
LMArena Vision: English	Not measured	1318	Only Gemini 3.8 Flash measured
LMArena Vision: Chinese	Not measured	1416	Only Gemini 3.8 Flash measured
LMArena Vision: reading text	Not measured	1333	Only Gemini 3.8 Flash measured
LMArena Vision: humor	Not measured	1321	Only Gemini 3.8 Flash measured
LMArena Vision: creative writing	Not measured	1299	Only Gemini 3.8 Flash measured
LMArena Document	1462	Not measured	Only Claude Opus 4.5 measured
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

Image generation benchmarks for Claude Opus 4.5 and Gemini 3.8 Flash
Benchmark	Claude Opus 4.5	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

Claude Opus 4.5$0.018Fits in one request

Gemini 3.8 Flash$0.0026Fits in one request

Gemini 3.8 Flash costs less

Repository review

50K input + 3K output tokens

Claude Opus 4.5$0.325Fits in one request

Gemini 3.8 Flash$0.049Fits in one request

Gemini 3.8 Flash costs less

Agent loop

200K input + 10K output tokens

Claude Opus 4.5$1.25Exceeds the context window

Gemini 3.8 Flash$0.188Fits in one request

Gemini 3.8 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.

Specifications of Claude Opus 4.5 and Gemini 3.8 Flash
Specification	Anthropic Claude Opus 4.5	Google Gemini 3.8 Flash
Maker	Anthropic	Google
Weights	No public weights listed	No public weights listed
Released	November 24, 2025	September 2, 2026
Context window	200K	1.05M
Input $/Mtok	$5.00	$0.75
Output $/Mtok	$25.00	$3.75
Coding index	44.0	61.6
Independent measurements behind it	3	6
Cost per solved task	$1.37	$2.74
Source	OpenRouter listing	OpenRouter listing

Questions

Is Claude Opus 4.5 better than Gemini 3.8 Flash for coding?

Pick Gemini 3.8 Flash for coding: it scores 61.6 on the Vibe Coding Index against 44.0 for Claude Opus 4.5. Pick Claude Opus 4.5 for a lower cost per solved task ($1.37 against $2.74) and work measured by Design Arena: agents building Android apps or TaxEval (Vals AI), where it leads.

Which is cheaper, Claude Opus 4.5 or Gemini 3.8 Flash?

Claude Opus 4.5 costs $5.00 per million input tokens and $25.00 per million output tokens; Gemini 3.8 Flash costs $0.75 and $3.75. Per solved SWE-bench Verified task, Claude Opus 4.5 costs $1.37 and Gemini 3.8 Flash $2.74.

Which has the bigger context window, Claude Opus 4.5 or Gemini 3.8 Flash?

Gemini 3.8 Flash, with 1.05M tokens against 200K.

How many benchmarks is the Claude Opus 4.5 vs Gemini 3.8 Flash comparison based on?

77 benchmarks have a result for both models as of October 21, 2026. Claude Opus 4.5's coding index rests on 3 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.

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Claude Opus 4.5 or Gemini 3.8 Flash: which to pick

Which one for your work

Coding

Intelligence

Agentic work

Reasoning

Math

Knowledge

Web design

General

Long documents

Everyday cost

Cost per solved task

At a glance

Benchmark by benchmark

What each workload costs

Chat turn

Repository review

Agent loop

Specification differences

Questions

Compare next