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LLM Toolkit

Model comparison

Gemini 3.5 Flash vs GPT-5 mini

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

Cheaper input

GPT-5 mini

$0.25 /1M in

Cheaper output

GPT-5 mini

$2.00 /1M out

Bigger context

Gemini 3.5 Flash

1M tokens

Head to head

Spec Gemini 3.5 Flash GPT-5 mini
Input / 1M tokens $1.50 $0.25
Cached input / 1M — $0.025
Output / 1M tokens $9.00 $2.00
Context window 1M 400K
Provider Google OpenAI
Price verified 2026-08-25 2026-08-25

Monthly cost at three real workloads

Workload Gemini 3.5 Flash GPT-5 mini Winner
Side-project chatbot 30K req · 2,000 in / 500 out · 40% cached $225.00/mo $39.60/mo GPT-5 mini
Coding agent 500K req · 12,000 in / 1,500 out · 70% cached $15,750/mo $2,055/mo GPT-5 mini
Bulk extraction 2,000K req · 800 in / 120 out · 20% cached $4,560/mo $808.00/mo GPT-5 mini

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 Gemini 3.5 Flash if…

  • You prefer its $1.50 input rate for read-heavy workloads.
  • You need the larger 1M context window.
  • You value its provider ecosystem and tooling.

Pick GPT-5 mini if…

  • You generate long outputs — $2.00 per 1M output vs $9.00 adds up fast.
  • Its 400K window covers your typical request with headroom.
  • You want cheaper total spend at your exact volumes — verify with the calculator above.

Frequently asked questions

Is Gemini 3.5 Flash cheaper than GPT-5 mini?

GPT-5 mini is cheaper on input at $0.25 per 1M tokens vs $1.50 — input pricing is 6.0× more expensive. On output, GPT-5 mini wins at $2.00 vs $9.00. At a balanced workload (100K requests, 2K in / 500 out), GPT-5 mini runs $150.00/mo vs $750.00/mo — a 5.0× difference.

Gemini 3.5 Flash vs GPT-5 mini: which has the bigger context window?

Gemini 3.5 Flash, with 1M tokens vs 400K — 2.5× more room. Filling Gemini 3.5 Flash's window once costs $1.50 at list price, vs $0.100 for the smaller window.

Should I switch from Gemini 3.5 Flash to GPT-5 mini?

Switch if your bottleneck matches GPT-5 mini's strengths: its 400K context fits your documents and cheaper output tokens ($2.00 vs $9.00). Stay on Gemini 3.5 Flash 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.