ResearchLLM Verifications Leaderboard

Data as of · 78 models, 80 questions · reviewed by Suhas Bhairav · methodology

Head to head · tested 27 Oct 2026

Claude Sonnet 5.5 vs Gemini 3.8 Flash: accuracy, speed and price

Similar accuracy; Gemini 3.8 Flash costs less per question.

AnthropicClaude Sonnet 5.578.8% score · #7$0.0054 per question126 tok/sGoogleGemini 3.8 Flash82.5% score · #3$0.0037 per question142 tok/s

Verdict

Built from the measurements below

  • Accuracy is too close to call: Claude Sonnet 5.5 scored 78.8% and Gemini 3.8 Flash 82.5% on the same 80 questions, a gap within what chance alone could produce.
  • Gemini 3.8 Flash is 1.5× cheaper per question as billed ($0.0037 vs $0.0054), reasoning tokens included.
  • Gemini 3.8 Flash generates text 1.1× faster: 142 tokens per second against 126.
  • Claude Sonnet 5.5 starts answering sooner: 0.7 s to the first token, against 3.2 s for Gemini 3.8 Flash.

Which should you choose?

Choose Claude Sonnet 5.5 for a quicker first token, shorter outputs (about 456 tokens per question against 925) and more hosts to choose from on OpenRouter (5 against 2). Choose Gemini 3.8 Flash for the lower cost per correct answer ($0.0045 against $0.0069) and faster streaming. The widest subject gap is in law: Gemini 3.8 Flash answered 6 of 6 correctly, Claude Sonnet 5.5 3 of 6. With so few questions per subject, treat this as a lead to test on your own prompts, not a result.

Accuracy gap -3.7 points (z = -0.60). A winner is called only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.

Head to head

Same questions, same prompt, same API

MeasureClaude Sonnet 5.5Gemini 3.8 FlashEdge
Verification scoreHigher is better78.8%82.5%Too close to call
Cost per questionLower is better$0.0054$0.0037Gemini 3.8 Flash
Output speedHigher is better126142Gemini 3.8 Flash
Time to first tokenLower is better0.7 s3.2 sClaude Sonnet 5.5
End-to-end response timeLower is better6.2 s5.6 sGemini 3.8 Flash
Tokens per questionLower is better456925Claude Sonnet 5.5
Context windowHigher is better1M1MSimilar

Side by side

Bars are scaled to the larger of the two values. The winner on each measure is marked in bold.

Every measure

Claude Sonnet 5.5 first, Gemini 3.8 Flash second

Verification scorehigher is better
Claude Sonnet 5.578.8%
Gemini 3.8 Flash82.5%
Cost per questionlower is better
Claude Sonnet 5.5$0.0054
Gemini 3.8 Flash$0.0037
Output speedhigher is better
Claude Sonnet 5.5126
Gemini 3.8 Flash142
Time to first tokenlower is better
Claude Sonnet 5.50.7 s
Gemini 3.8 Flash3.2 s
End-to-end response timelower is better
Claude Sonnet 5.56.2 s
Gemini 3.8 Flash5.6 s
Tokens per questionlower is better
Claude Sonnet 5.5456
Gemini 3.8 Flash925
Context windowhigher is better
Claude Sonnet 5.51M
Gemini 3.8 Flash1M

Score vs. cost per question

Both models in color, every other model in grey

Most attractive quadrant0255075100$0.00001$0.0001$0.001$0.01$0.10Cost per question (USD, log) →Verification score (%) →Qwen3.8 2.4T A95BCommand AReka Flash 3Gemma 4 26B A4BGemma 4 31BQwen3.5 397B A17BHermes 4 405BMuse WonderGrok 4.7o3gpt-oss-20bMinistral 3 3B 2512Nova Micro 1.0Phi 4Granite 4.2 8BHy3GLM 5.3 FlashSolar Pro 4Trinity Large ThinkingMiniMax M3Mistral Large 4Claude Opus 5.5Gemini 3.8 FlashGPT-6.1 SolGPT-5.4GPT-6 Lunagpt-oss-120bLlama 4 Maverick

Specifications and pricing

From OpenRouter's catalogue, plus the leaderboard's test dates

SpecificationClaude Sonnet 5.5Gemini 3.8 Flash
CreatorAnthropicGoogle
Released28 Sept 20262 Sept 2026
Weights——
ReasoningYesYes
Inputtext, image, filetext, image, video, file, audio
Outputtexttext
Context window1M tokens1M tokens
Knowledge cutoff——
List price in / out per 1M$2 / $10$0.825 / $4.125
Blended price per 1M (3:1)$4.00$1.65
Cheapest hostGoogle · $2 / $10Google AI Studio · $0.375 / $1.875
Hosts on OpenRouter52
Last tested25 Oct 202625 Oct 2026

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Claude Sonnet 5.5 vs Gemini 3.8 Flash: frequently asked questions

Is Claude Sonnet 5.5 better than Gemini 3.8 Flash?
On accuracy they are statistically tied: Claude Sonnet 5.5 scored 78.8% and Gemini 3.8 Flash 82.5% on the same 80 questions from open datasets. Similar accuracy; Gemini 3.8 Flash costs less per question.
Which is cheaper, Claude Sonnet 5.5 or Gemini 3.8 Flash?
Gemini 3.8 Flash is cheaper: $0.0037 per question as billed, against $0.0054. List prices: Claude Sonnet 5.5 $2 in / $10 out, Gemini 3.8 Flash $0.825 in / $4.125 out per million tokens.
Which is faster, Claude Sonnet 5.5 or Gemini 3.8 Flash?
Gemini 3.8 Flash is faster at 142 output tokens per second, against 126. Time to first token: 0.7 s for Claude Sonnet 5.5, 3.2 s for Gemini 3.8 Flash.
Which has the larger context window, Claude Sonnet 5.5 or Gemini 3.8 Flash?
Both accept about the same amount of context: 1M and 1M tokens.