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LLM Toolkit

Model comparison

o3 vs GPT-5

Verified pricing, context windows and real-workload costs for both models — computed from official provider rates as of 2026-08-26.

Cheaper input

GPT-5

$1.25 /1M in

Cheaper output

o3

$8.00 /1M out

Bigger context

GPT-5

400K tokens

Head to head

Spec o3 GPT-5
Input / 1M tokens $2.00 $1.25
Cached input / 1M $0.50 $0.125
Output / 1M tokens $8.00 $10.00
Context window 200K 400K
Provider OpenAI OpenAI
Price verified 2026-08-26 2026-08-26

Monthly cost at three real workloads

Workload o3 GPT-5 Winner
Side-project chatbot 30K req · 2,000 in / 500 out · 40% cached $204.00/mo $198.00/mo GPT-5
Coding agent 500K req · 12,000 in / 1,500 out · 70% cached $11,700/mo $10,275/mo GPT-5
Bulk extraction 2,000K req · 800 in / 120 out · 20% cached $4,640/mo $4,040/mo GPT-5

Computed from list prices verified 2026-08-26. 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 o3 if…

  • You prefer its $2.00 input rate for read-heavy workloads.
  • Your documents fit its 200K window comfortably.
  • You value its provider ecosystem and tooling.

Pick GPT-5 if…

  • Output-heavy agent loops favor its $10.00 output rate.
  • You need 400K 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 o3 cheaper than GPT-5?

GPT-5 is cheaper on input at $1.25 per 1M tokens vs $2.00 — input pricing is 1.6× more expensive. On output, o3 wins at $8.00 vs $10.00. At a balanced workload (100K requests, 2K in / 500 out), GPT-5 runs $750.00/mo vs $800.00/mo — a 1.1× difference.

o3 vs GPT-5: which has the bigger context window?

GPT-5, with 400K tokens vs 200K — 2.0× more room. Filling GPT-5's window once costs $0.500 at list price, vs $0.400 for the smaller window.

Should I switch from o3 to GPT-5?

Switch if your bottleneck matches GPT-5's strengths: the larger 400K context and its pricing profile. Stay on o3 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.