Compare / Claude Sonnet 5.5 vs Gemini 3.8 Flash
Claude Sonnet 5.5 vs Gemini 3.8 Flash
A side by side look at published price, context window and benchmark scores for these two models. Every number links to its source. A missing field means that model has not published a number for that metric.
What this means for your work
Gemini 3.8 Flash costs much less ($0.75 in, $3.75 out vs $2 and $10) and starts answering far sooner at the settings tested. Claude Sonnet 5.5 scores higher on the Artificial Analysis index (56 vs 41) and LMArena WebDev, while Flash is higher on LMArena Text. For high volume jobs like summaries and inbox sorting, Flash's price and speed stand out; for coding, Sonnet scores higher.
Input price
Lower is betterClaude Sonnet 5.5: source Vendor pricing page, as of Oct 27, 2026. Claude API base input USD per 1M tokens
Gemini 3.8 Flash: source Vendor pricing page, as of Oct 27, 2026. first paid tier under Gemini 3.8 Flash through 2026-12-31; $1.50 from 2027-01-01
Output price
Lower is betterClaude Sonnet 5.5: source Vendor pricing page, as of Oct 27, 2026. Claude API base output USD per 1M tokens
Gemini 3.8 Flash: source Vendor pricing page, as of Oct 27, 2026. first paid tier including thinking tokens through 2026-12-31; $7.50 from 2027-01-01
Context window
Higher is betterClaude Sonnet 5.5: source Vendor model page, as of Oct 27, 2026. 1M token context window
Gemini 3.8 Flash: source Vendor model page, as of Oct 22, 2026. input token limit; page last updated 2026-10-22 UTC
Output speed
Higher is betterClaude Sonnet 5.5: source Artificial Analysis, as of Oct 27, 2026. max, default fallback; Anthropic API
Gemini 3.8 Flash: source Artificial Analysis, as of Oct 27, 2026. high; Google API; page shows 134.0
Time to first token
Lower is betterFor reasoning settings, Artificial Analysis counts thinking time before the first answer token, so long waits are expected on max effort modes.
Claude Sonnet 5.5: source Artificial Analysis, as of Oct 27, 2026. max, default fallback; AA FAQ TTFT, includes thinking on this reasoning setting
Gemini 3.8 Flash: source Artificial Analysis, as of Oct 27, 2026. high; AA FAQ TTFT; comparison table shows 28.27s
Artificial Analysis Intelligence Index
Higher is betterComposite of several evaluations run by Artificial Analysis at the setting shown.
Claude Sonnet 5.5: source Artificial Analysis, as of Oct 27, 2026. max, default fallback; AA index integer
Gemini 3.8 Flash: source Artificial Analysis, as of Oct 27, 2026. high reasoning; AA index integer
LMArena Text score
Higher is betterBars start at 1300, not 0, to make differences easier to see.
Claude Sonnet 5.5: source LMArena Text, as of Oct 22, 2026. Reported for Claude Sonnet 5.5 (xHigh).
Gemini 3.8 Flash: source LMArena Text, as of Oct 22, 2026. Reported for Gemini 3.8 Flash (High).
LMArena WebDev score
Higher is betterBars start at 1300, not 0, to make differences easier to see.
Claude Sonnet 5.5: source LMArena WebDev, as of Oct 23, 2026. Reported for Claude Sonnet 5.5 (xHigh).
Gemini 3.8 Flash: source LMArena WebDev, as of Oct 23, 2026. Reported for Gemini 3.8 Flash (High).
Humanity's Last Exam (no tools)
Higher is betterGemini 3.8 Flash: source Artificial Analysis, as of Oct 27, 2026. high; AA HLE with tool usage marked off
All metrics
| Metric | Claude Sonnet 5.5 | Gemini 3.8 Flash |
|---|---|---|
| Input price | $2.00as of Oct 27, 2026 | $0.75as of Oct 27, 2026 |
| Output price | $10as of Oct 27, 2026 | $3.75as of Oct 27, 2026 |
| Context window | 1M tokensas of Oct 27, 2026 | 1.05M tokensas of Oct 22, 2026 |
| Output speed | 141.2 tok/sas of Oct 27, 2026 | 134 tok/sas of Oct 27, 2026 |
| Time to first token | 461.94 sas of Oct 27, 2026 | 28.67 sas of Oct 27, 2026 |
| Artificial Analysis Intelligence Index | 56 pointsas of Oct 27, 2026 | 41 pointsas of Oct 27, 2026 |
| LMArena Text score | 1473as of Oct 22, 2026 | 1498as of Oct 22, 2026 |
| LMArena WebDev score | 1769as of Oct 23, 2026 | 1585as of Oct 23, 2026 |
| Humanity's Last Exam (no tools) | Not published | 47.8%as of Oct 27, 2026 |