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SOLVENCY

Head to head

GPT-5 vs o3

GPT-5: legacyo3: legacyheavy tier

Verdict · modelled basis

GPT-5 costs 1.2x less per solved task.

On output token price alone, o3 looks 1.3x cheaper (1.6x on input). The ranking reverses once you divide by pass rate — the cheaper tokens do not win the task.

Source: Aider polyglot benchmark · verified 2026-08-21 · prices from each provider's pricing page

Input $/M tokens

lower is better

  • GPT-5$1.25
  • o3$2

Output $/M tokens

lower is better

  • GPT-5$10
  • o3$8

Cost per solved task

modelled basis · lower is better

  • GPT-5$1.66
  • o3$1.99
GPT-5o3
Input $/Mtok$1.25$2
Output $/Mtok$10$8
Cached input $/Mtok$0.125$0.5
Pass rate88%81%
Pass rate sourceAiderAider
Cost basismodelledmodelled
Cost per solved task$1.66$1.99

verified 2026-08-21 · heavy task tier; measured rows ignore the tier· Methodology· GPT-5· o3