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Head-to-head comparison

Claude Sonnet 5 vs Gemini 3.8 Flash

Claude Sonnet 5 (Anthropic) and Gemini 3.8 Flash (Google) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 3 September 2026

As of 3 September 2026, Gemini 3.8 Flash holds the stronger ModelCap Index position (#11 vs #15); and Gemini 3.8 Flash is 2.7× cheaper per output token ($3.75/1M vs $10.00/1M).

Which should you choose?

Choose Claude Sonnet 5 if…

  • you want provider choice — 5 listed API providers against 2.

Choose Gemini 3.8 Flash if…

  • you want the stronger overall ModelCap Index position — #11 against #15 (76.4 vs 74.2 points).
  • API cost matters — $3.75/1M output tokens against $10.00/1M, about 2.7× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.75/1M against $2.00/1M.
  • AA Intelligence Index is your yardstick — 58.7 against 55.3.
  • AA Terminal-Bench 2.1 is your yardstick — 87.6% against 80.5%.
  • AA Humanity's Last Exam is your yardstick — 47.8% against 41.3%.
  • you want the more recently listed model — Gemini 3.8 Flash was listed 2 September 2026, Claude Sonnet 5 30 June 2026.

Claude Sonnet 5 vs Gemini 3.8 Flash: specs, pricing and context

Specification comparison of Claude Sonnet 5 and Gemini 3.8 Flash
FieldClaude Sonnet 5AnthropicGemini 3.8 FlashGoogle
ModelCap Index position#15#11
Index score74.276.4
EvidenceMeasuredMeasured
Input price / 1M tokens$2.00$0.75
Output price / 1M tokens$10.00$3.75
Context window1M tokens1M tokens
Max output tokens128K66K
API providers listed52
Weight accessAPI onlyAPI only
Input modalitiesText, Image, FileText, Image, Video, File, Audio
First listed30 June 20262 September 2026
PublisherAnthropicGoogle

Evidence: 4 public benchmark observations across 4 boards · 1 public benchmark observation across 1 board. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Claude Sonnet 5 vs Gemini 3.8 Flash

Public benchmark boards where Claude Sonnet 5 or Gemini 3.8 Flash has a published result
BoardClaude Sonnet 5Gemini 3.8 FlashLeads
Arena codingArena (LMArena)15211513–1528High—Only one result
LMArena AgentLMArena7.5%5.3%–9.7%High—Only one result
AA Intelligence IndexArtificial Analysis55.3intelligence-index58.7intelligence-indexGemini 3.8 Flash
AA Terminal-Bench 2.1Artificial Analysis80.5%terminal-bench-2.187.6%terminal-bench-2.1Gemini 3.8 Flash
AA Humanity's Last ExamArtificial Analysis41.3%humanitys-last-exam47.8%humanitys-last-examGemini 3.8 Flash
Terminal-Bench 4.0Terminal-Bench (Laude Institute)12.4%9.4%–15.5%Claude Code · Max—Only one result

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

Claude Sonnet 5 vs Gemini 3.8 Flash: common questions

Is Claude Sonnet 5 better than Gemini 3.8 Flash?

Gemini 3.8 Flash ranks higher on the ModelCap Index as of 3 September 2026: #11 against #15. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it.

Is Claude Sonnet 5 cheaper than Gemini 3.8 Flash?

Gemini 3.8 Flash is cheaper on output tokens: $3.75/1M against $10.00/1M. Input tokens are $2.00/1M for Claude Sonnet 5 and $0.75/1M for Gemini 3.8 Flash. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens.

Which has the bigger context window, Claude Sonnet 5 or Gemini 3.8 Flash?

Both publish a 1M-token context window.

Which is better for coding, Claude Sonnet 5 or Gemini 3.8 Flash?

AA Terminal-Bench 2.1: Claude Sonnet 5 80.5%, Gemini 3.8 Flash 87.6% — Gemini 3.8 Flash leads.

Are Claude Sonnet 5 and Gemini 3.8 Flash open-weight models?

Claude Sonnet 5: API only. Gemini 3.8 Flash: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run Claude Sonnet 5 and Gemini 3.8 Flash?

ModelCap currently lists 5 API providers for Claude Sonnet 5 and 2 for Gemini 3.8 Flash, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Claude Sonnet 5 vs Gemini 3.8 Flash comparison?

Every figure comes from the sealed ModelCap dataset published 3 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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