Claude Sonnet 4.5 vs Gemini 3.8 Flash

Gemini 3.8 Flash leads Claude Sonnet 4.5 on coding, 61.6 to 39.5 on the Vibe Coding Index, and Gemini 3.8 Flash costs 4.0x less per output token ($3.75 vs $15.00 per million). Updated October 22, 2026; 74 benchmarks have a result for both.

Replace Claude Sonnet 4.5 Replace Gemini 3.8 Flash

Claude Sonnet 4.5Anthropic

Coding: 39.5
Overall: 49.5
Output $/M: $15.00

Gemini 3.8 FlashGoogle

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

vs boards won of 74 shared

Claude Sonnet 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 39.5 for Claude Sonnet 4.5.

Pick Claude Sonnet 4.5 for a lower cost per solved task ($1.16 against $2.74) and work measured by SAGE (Vals AI) or MedScribe (Vals AI), where it leads.

Model AClaude Sonnet 4.5Anthropic39.5/1003 independent benchmarks$1.16 per solved task Model BGemini 3.8 FlashGoogle61.6/1006 independent benchmarks$2.74 per solved task

742154

Shared results: 74
Claude Sonnet 4.5 only: 21
Gemini 3.8 Flash only: 54
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 39.5.
3 and 6 benchmarks behind the scores
Intelligence
AA Intelligence Index
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 40.9 against 20.7.
Same board, both measured
Agentic work
AA Agentic Index
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 40.2 against 15.8.
Same board, both measured
Reasoning
GPQA Diamond
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 94.4% against 81.6%.
Same board, both measured
Math
AIME
No call
Only Claude Sonnet 4.5 has a AIME result, 88.2%.
Directional only
Knowledge
MMLU Pro
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 90.2% against 87.4%.
Same board, both measured
Web design
Design Arena: websites
Gemini 3.8 Flash
Gemini 3.8 Flash leads, 1300 against 1189.
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 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Gemini 3.8 Flash
Claude Sonnet 4.5 $0.011, Gemini 3.8 Flash $0.0026 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
Claude Sonnet 4.5
Claude Sonnet 4.5 $1.16, Gemini 3.8 Flash $2.74.
Published attempt cost and pass rate

At a glance

Coding index: Claude Sonnet 4.5 39.5 from 3 benchmarks, Gemini 3.8 Flash 61.6 from 6 benchmarks.
Widest category: Coding, 24.6 points apart on average over 10 shared benchmarks.
Widest single gap: ARC-AGI-2: Claude Sonnet 4.5 13.6% against Gemini 3.8 Flash 89.2%, 75.6 points apart on a 0 to 100 scale.
Output price: Claude Sonnet 4.5 $15.00 against Gemini 3.8 Flash $3.75 per million output tokens, 4.0x apart.
Context window: Claude Sonnet 4.5 takes 1M 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 Sonnet 4.5	Gemini 3.8 Flash
Coding	0	10
Intelligence	0	2
Agentic work	0	6
Reasoning	0	10
Math	0	6
Knowledge	0	11
Web design	0	8
General	2	19
All shared boards	2	72

CodingLike-for-likeSix of these boards feed the Vibe Coding Index010

Coding benchmarks for Claude Sonnet 4.5 and Gemini 3.8 Flash
Benchmark	Claude Sonnet 4.5	Gemini 3.8 Flash	Leader
SWE-bench Verified	74.8%	Not measured	Only Claude Sonnet 4.5 measured
SWE-bench Multilingual	67.0%	Not measured	Only Claude Sonnet 4.5 measured
LiveBench coding	Not measured	82.2%	Only Gemini 3.8 Flash measured
LMArena WebDev	1394	1585	Gemini 3.8 Flash
AA Coding Index	52.1	76.3	Gemini 3.8 Flash
LiveCodeBench (Vals AI)	73.0%	89.5%	Gemini 3.8 Flash
SWE-bench Verified (Vals AI)	70.0%	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)	22.6%	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
SciCode	Not measured	56.6%	Only Gemini 3.8 Flash measured
Terminal-Bench	46.5%	Not measured	Only Claude Sonnet 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	14.7%	Not measured	Only Claude Sonnet 4.5 measured
WeirdML	47.7%	84.8%	Gemini 3.8 Flash
Cybench	60.0%	Not measured	Only Claude Sonnet 4.5 measured
ALE-Bench	Not measured	1269.7	Only Gemini 3.8 Flash measured
LMArena Text: coding	1488	1508	Gemini 3.8 Flash
LMArena Text: software and IT	1473	1507	Gemini 3.8 Flash
LMArena WebDev: React	1386	1577	Gemini 3.8 Flash
LMArena WebDev: HTML	1399	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 8 boards here

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

Intelligence benchmarks for Claude Sonnet 4.5 and Gemini 3.8 Flash
Benchmark	Claude Sonnet 4.5	Gemini 3.8 Flash	Leader
AA Intelligence Index	20.7	40.9	Gemini 3.8 Flash
Epoch Capabilities Index	146.7	157.4	Gemini 3.8 Flash

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

Agentic work benchmarks for Claude Sonnet 4.5 and Gemini 3.8 Flash
Benchmark	Claude Sonnet 4.5	Gemini 3.8 Flash	Leader
AA Agentic Index	15.8	40.2	Gemini 3.8 Flash
Design Arena: agents building web apps	1060	1238	Gemini 3.8 Flash
Design Arena: agents building full-stack apps	1050	1244	Gemini 3.8 Flash
Design Arena: agents building mobile apps	1137	1236	Gemini 3.8 Flash
Design Arena: agents building Android apps	Not measured	1078	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	1153	Only Gemini 3.8 Flash measured
Design Arena: spreadsheets	Not measured	1022	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
APEX-Agents	Not measured	64.3%	Only Gemini 3.8 Flash measured
METR time horizons	67.4%	Not measured	Only Claude Sonnet 4.5 measured
Remote Labor Index	2.1%	5.8%	Gemini 3.8 Flash
GDPval	42.5%	Not measured	Only Claude Sonnet 4.5 measured
DeepResearch Bench	52.6%	Not measured	Only Claude Sonnet 4.5 measured
OSWorld	62.9%	Not measured	Only Claude Sonnet 4.5 measured
Vending-Bench 2	$3,839	$5,094	Gemini 3.8 Flash
Berkeley Function Calling Leaderboard (BFCL)	73.2%	Not measured	Only Claude Sonnet 4.5 measured
Neither model has a result on the other 11 boards here

ReasoningLike-for-likePublic boards, shown as published, kept out of the index010

Reasoning benchmarks for Claude Sonnet 4.5 and Gemini 3.8 Flash
Benchmark	Claude Sonnet 4.5	Gemini 3.8 Flash	Leader
GPQA Diamond	81.6%	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)	79.3%	89.1%	Gemini 3.8 Flash
GPQA Diamond (Artificial Analysis run)	Not measured	95.3%	Only Gemini 3.8 Flash measured
Humanity's Last Exam (Artificial Analysis run)	Not measured	47.8%	Only Gemini 3.8 Flash measured
GPQA Diamond (Epoch AI run)	82.3%	95.4%	Gemini 3.8 Flash
ARC-AGI	63.7%	98.5%	Gemini 3.8 Flash
ARC-AGI-2	13.6%	89.2%	Gemini 3.8 Flash
SimpleBench	54.3%	Not measured	Only Claude Sonnet 4.5 measured
Chess puzzles	10.0%	58.0%	Gemini 3.8 Flash
Mystery game puzzles	17.0%	47.0%	Gemini 3.8 Flash
EBR-bench	2.4%	Not measured	Only Claude Sonnet 4.5 measured
VPCT	39.8%	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: hard prompts	1462	1509	Gemini 3.8 Flash
LMArena Text: expert	1483	1526	Gemini 3.8 Flash
LMArena Text: hard prompts in English	1471	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	57.9%	Not measured	Only Claude Sonnet 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 Sonnet 4.5 and Gemini 3.8 Flash
Benchmark	Claude Sonnet 4.5	Gemini 3.8 Flash	Leader
AIME	88.2%	Not measured	Only Claude Sonnet 4.5 measured
MGSM (Vals AI)	94.3%	Not measured	Only Claude Sonnet 4.5 measured
OTIS Mock AIME	77.8%	98.9%	Gemini 3.8 Flash
FrontierMath, tiers 1 to 3	23.9%	68.4%	Gemini 3.8 Flash
FrontierMath, tier 4	2.4%	22.0%	Gemini 3.8 Flash
ProofBench	19.0%	48.0%	Gemini 3.8 Flash
MATH level 5	97.7%	Not measured	Only Claude Sonnet 4.5 measured
LMArena Text: math	1449	1532	Gemini 3.8 Flash
LMArena Text: mathematical work	1462	1519	Gemini 3.8 Flash
Neither model has a result on the other 4 boards here

KnowledgeLike-for-likePublic boards, shown as published, kept out of the index011

Knowledge benchmarks for Claude Sonnet 4.5 and Gemini 3.8 Flash
Benchmark	Claude Sonnet 4.5	Gemini 3.8 Flash	Leader
MMLU Pro	87.4%	90.2%	Gemini 3.8 Flash
LegalBench (Vals AI)	84.1%	87.0%	Gemini 3.8 Flash
CaseLaw (Vals AI)	62.2%	Not measured	Only Claude Sonnet 4.5 measured
CorpFin (Vals AI)	62.0%	Not measured	Only Claude Sonnet 4.5 measured
TaxEval (Vals AI)	73.3%	74.5%	Gemini 3.8 Flash
MortgageTax (Vals AI)	64.0%	65.3%	Gemini 3.8 Flash
MedQA (Vals AI)	94.7%	Not measured	Only Claude Sonnet 4.5 measured
MedCode (Vals AI)	44.1%	48.1%	Gemini 3.8 Flash
SimpleQA Verified	30.7%	69.7%	Gemini 3.8 Flash
LMArena Text: science	1448	1523	Gemini 3.8 Flash
LMArena Text: medicine and healthcare	1444	1508	Gemini 3.8 Flash
LMArena Text: legal and government	1451	1497	Gemini 3.8 Flash
LMArena Text: business and finance	1440	1479	Gemini 3.8 Flash
FACTS Benchmark Suite	40.6%	69.4%	Gemini 3.8 Flash
Neither model has a result on the other 4 boards here

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

Web design benchmarks for Claude Sonnet 4.5 and Gemini 3.8 Flash
Benchmark	Claude Sonnet 4.5	Gemini 3.8 Flash	Leader
Design Arena: websites	1189	1300	Gemini 3.8 Flash
Design Arena: UI components	1170	1316	Gemini 3.8 Flash
Design Arena: game dev	1166	1304	Gemini 3.8 Flash
Design Arena: data viz	1167	1270	Gemini 3.8 Flash
Design Arena: 3D	1157	1294	Gemini 3.8 Flash
Design Arena: all code categories	1182	1303	Gemini 3.8 Flash
Design Arena: SVG	1115	1296	Gemini 3.8 Flash
Design Arena: ASCII art	1205	1262	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 index219

General benchmarks for Claude Sonnet 4.5 and Gemini 3.8 Flash
Benchmark	Claude Sonnet 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)	36.1%	35.1%	Claude Sonnet 4.5
MedScribe (Vals AI)	84.5%	84.5%	Claude Sonnet 4.5
Long context reasoning (AA-LCR)	Not measured	84.0%	Only Gemini 3.8 Flash measured
DTBench	83.2%	95.7%	Gemini 3.8 Flash
LMCA	38.8%	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	1438	1499	Gemini 3.8 Flash
LMArena Text: instruction following	1459	1492	Gemini 3.8 Flash
LMArena Text: creative writing	1442	1488	Gemini 3.8 Flash
LMArena Vision	Not measured	1315	Only Gemini 3.8 Flash measured
LMArena Text: English	1450	1498	Gemini 3.8 Flash
LMArena Text: non-English	1425	1491	Gemini 3.8 Flash
LMArena Text: Chinese	1460	1553	Gemini 3.8 Flash
LMArena Text: German	1427	1501	Gemini 3.8 Flash
LMArena Text: Japanese	1390	1507	Gemini 3.8 Flash
LMArena Text: Korean	1402	1464	Gemini 3.8 Flash
LMArena Text: French	1459	1496	Gemini 3.8 Flash
LMArena Text: Spanish	1458	1487	Gemini 3.8 Flash
LMArena Text: Russian	1437	1514	Gemini 3.8 Flash
LMArena Text: Polish	1423	1497	Gemini 3.8 Flash
LMArena Text: multi-turn	1465	1503	Gemini 3.8 Flash
LMArena Text: longer queries	1475	1507	Gemini 3.8 Flash
LMArena Text: writing and language	1442	1494	Gemini 3.8 Flash
LMArena Text: entertainment and media	1428	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	1450	Not measured	Only Claude Sonnet 4.5 measured
Neither model has a result on the other 12 boards here

Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared

Image generation benchmarks for Claude Sonnet 4.5 and Gemini 3.8 Flash
Benchmark	Claude Sonnet 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 Sonnet 4.5$0.011Fits 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 Sonnet 4.5$0.195Fits 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 Sonnet 4.5$0.750Fits in one request

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 Sonnet 4.5 and Gemini 3.8 Flash
Specification	Anthropic Claude Sonnet 4.5	Google Gemini 3.8 Flash
Maker	Anthropic	Google
Weights	No public weights listed	No public weights listed
Released	September 29, 2025	September 2, 2026
Context window	1M	1.05M
Input $/Mtok	$3.00	$0.75
Output $/Mtok	$15.00	$3.75
Coding index	39.5	61.6
Independent measurements behind it	3	6
Cost per solved task	$1.16	$2.74
Source	OpenRouter listing	OpenRouter listing

Questions

Is Claude Sonnet 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 39.5 for Claude Sonnet 4.5. Pick Claude Sonnet 4.5 for a lower cost per solved task ($1.16 against $2.74) and work measured by SAGE (Vals AI) or MedScribe (Vals AI), where it leads.

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

Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens; Gemini 3.8 Flash costs $0.75 and $3.75. Per solved SWE-bench Verified task, Claude Sonnet 4.5 costs $1.16 and Gemini 3.8 Flash $2.74.

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

Gemini 3.8 Flash, with 1.05M tokens against 1M.

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

74 benchmarks have a result for both models as of October 22, 2026. Claude Sonnet 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 Sonnet 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