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LLM Toolkit

Model comparison

Claude Opus 5 vs Gemini 3.5 Flash

Verified pricing, context windows and real-workload costs for both models — computed from official provider rates as of 2026-08-25.

Cheaper input

Gemini 3.5 Flash

$1.50 /1M in

Cheaper output

Gemini 3.5 Flash

$9.00 /1M out

Bigger context

Gemini 3.5 Flash

1M tokens

Head to head

Spec Claude Opus 5 Gemini 3.5 Flash
Input / 1M tokens $5.00 $1.50
Cached input / 1M $0.5 —
Output / 1M tokens $25.00 $9.00
Context window 200K 1M
Provider Anthropic Google
Price verified 2026-08-25 2026-08-25

Monthly cost at three real workloads

Workload Claude Opus 5 Gemini 3.5 Flash Winner
Side-project chatbot 30K req · 2,000 in / 500 out · 40% cached $567.00/mo $225.00/mo Gemini 3.5 Flash
Coding agent 500K req · 12,000 in / 1,500 out · 70% cached $29,850/mo $15,750/mo Gemini 3.5 Flash
Bulk extraction 2,000K req · 800 in / 120 out · 20% cached $12,560/mo $4,560/mo Gemini 3.5 Flash

Computed from list prices verified 2026-08-25. Cache savings blend normal and cached input rates by the hit rate; models without published cached rates use the base input price. Adjust every parameter yourself on the API Cost Calculator.

Pick Claude Opus 5 if…

  • You prefer its $5.00 input rate for read-heavy workloads.
  • Your documents fit its 200K window comfortably.
  • You run repeat-context workloads — cached input at $0.5 per 1M is the better deal.

Pick Gemini 3.5 Flash if…

  • You generate long outputs — $9.00 per 1M output vs $25.00 adds up fast.
  • You need 1M tokens of context for large codebases or document sets.
  • You want cheaper total spend at your exact volumes — verify with the calculator above.

Frequently asked questions

Is Claude Opus 5 cheaper than Gemini 3.5 Flash?

Gemini 3.5 Flash is cheaper on input at $1.50 per 1M tokens vs $5.00 — input pricing is 3.3× more expensive. On output, Gemini 3.5 Flash wins at $9.00 vs $25.00. At a balanced workload (100K requests, 2K in / 500 out), Gemini 3.5 Flash runs $750.00/mo vs $2,250/mo — a 3.0× difference.

Claude Opus 5 vs Gemini 3.5 Flash: which has the bigger context window?

Gemini 3.5 Flash, with 1M tokens vs 200K — 5.0× more room. Filling Gemini 3.5 Flash's window once costs $1.50 at list price, vs $1.00 for the smaller window.

Should I switch from Claude Opus 5 to Gemini 3.5 Flash?

Switch if your bottleneck matches Gemini 3.5 Flash's strengths: the larger 1M context and cheaper output tokens ($9.00 vs $25.00). Stay on Claude Opus 5 if your workload already fits its limits. Test both with your real token counts before committing.

Keep comparing

Or measure your real usage with the AI Token Counter and browse all rates on the Pricing Comparison.