GPT-5 vs O3
Data reconciled August 15, 2026
Short answer
GPT-5 and O3 each win on different axes — neither is simply cheaper or better across the board.
GPT-5 is 1.6× cheaper on input.
O3 is 1.3× cheaper on output.
GPT-5 holds a 1.4× larger context window.
GPT-5 returns a 1.3× longer answer per call.
Side by side
What it costs on your own workload
A price gap per million tokens says little until your volumes are plugged in: on a long fixed system prompt the winner is the model with cheap cache reads, not the one with a cheap input rate. Run GPT-5 and O3 against your own numbers.
Open the cost calculatorWhat is deliberately absent
We do not compare answer quality and we do not reprint third-party benchmarks. We have no quality measurements of our own, and external tables go stale faster than prices while being compiled, almost always, by someone with a stake in the result. What is here is only what we reconcile ourselves every day: prices, limits and supported capabilities.