ResearchLLM Verifications Leaderboard

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

Head to head · tested 27 Oct 2026

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

Similar accuracy; Gemini 3.8 Flash costs less per question.

AnthropicClaude Opus 5.585.0% score · #1$0.015 per question129 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 Opus 5.5 scored 85.0% 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 4.0× cheaper per question as billed ($0.0037 vs $0.015), reasoning tokens included.
  • Output speed is similar (129 vs 142 tokens per second).
  • Claude Opus 5.5 starts answering sooner: 2.3 s to the first token, against 3.2 s for Gemini 3.8 Flash.

Which should you choose?

Choose Claude Opus 5.5 for a quicker first token 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 $0.017).

Accuracy gap +2.5 points (z = 0.43). 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 Opus 5.5Gemini 3.8 FlashEdge
Verification scoreHigher is better85.0%82.5%Too close to call
Cost per questionLower is better$0.015$0.0037Gemini 3.8 Flash
Output speedHigher is better129142Similar
Time to first tokenLower is better2.3 s3.2 sClaude Opus 5.5
End-to-end response timeLower is better7.6 s5.6 sGemini 3.8 Flash
Tokens per questionLower is better645925Claude Opus 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 Opus 5.5 first, Gemini 3.8 Flash second

Verification scorehigher is better
Claude Opus 5.585.0%
Gemini 3.8 Flash82.5%
Cost per questionlower is better
Claude Opus 5.5$0.015
Gemini 3.8 Flash$0.0037
Output speedhigher is better
Claude Opus 5.5129
Gemini 3.8 Flash142
Time to first tokenlower is better
Claude Opus 5.52.3 s
Gemini 3.8 Flash3.2 s
End-to-end response timelower is better
Claude Opus 5.57.6 s
Gemini 3.8 Flash5.6 s
Tokens per questionlower is better
Claude Opus 5.5645
Gemini 3.8 Flash925
Context windowhigher is better
Claude Opus 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 Opus 5.5Gemini 3.8 Flash
CreatorAnthropicGoogle
Released22 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$4 / $20$0.825 / $4.125
Blended price per 1M (3:1)$8.00$1.65
Cheapest hostAmazon Bedrock · $4 / $20Google AI Studio · $0.375 / $1.875
Hosts on OpenRouter52
Last tested25 Oct 202625 Oct 2026

Compare any two models →

Claude Opus 5.5 vs Gemini 3.8 Flash: frequently asked questions

Is Claude Opus 5.5 better than Gemini 3.8 Flash?
On accuracy they are statistically tied: Claude Opus 5.5 scored 85.0% 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 Opus 5.5 or Gemini 3.8 Flash?
Gemini 3.8 Flash is cheaper: $0.0037 per question as billed, against $0.015. List prices: Claude Opus 5.5 $4 in / $20 out, Gemini 3.8 Flash $0.825 in / $4.125 out per million tokens.
Which is faster, Claude Opus 5.5 or Gemini 3.8 Flash?
Their output speed is similar: 129 and 142 tokens per second.
Which has the larger context window, Claude Opus 5.5 or Gemini 3.8 Flash?
Both accept about the same amount of context: 1M and 1M tokens.