o3 vs GPT-5.1: token pricing & cost compared (July 2026)

How o3 (OpenAI) and GPT-5.1 (OpenAI) actually compare on price — input, output, and total monthly cost at the MAU you care about. Updated against live OpenRouter pricing.

OpenAI

o3

Input: $2.00 / 1M tokens
Output: $8.00 / 1M tokens
Output / Input ratio: 4.0×
Context window: 200K

OpenAI

GPT-5.1

Input: $1.25 / 1M tokens
Output: $10.00 / 1M tokens
Output / Input ratio: 8.0×
Context window: 400K

The short answer

o3 wins for output-heavy work (chat, generation). GPT-5.1 wins for input-heavy work (RAG, summarisation, classification).

Token pricing side-by-side

o3
GPT-5.1

Cost at your usage

Avg input tokens / call

Avg output tokens / call

Calls per active user / day: 5

Active days / month: 20

MAU: 1,000

Per call

$0.00500

Per user / mo

$0.5000

Total / mo

$500

GPT-5.1

Per call

$0.00563

Per user / mo

$0.5625

Total / mo

$563

o3 is cheaper by $0.0625/user/month — a saving of $63/month at 1,000 MAU.

Total monthly bill across MAU

o3
GPT-5.1

Same usage profile applied to both models; only the per-token price differs.

Run this against your real numbers

The mini-calculator above is a preview. Use the full tools to model power-user blast radius, gross margin, and 12-month spend forecasts.

Other comparisons

DeepSeek V4 Pro vs GPT-5.1 Claude Sonnet 4.6 vs GPT-5.1 GPT-5.1 vs Claude Sonnet 4.5 GLM 5.2 vs GPT-5.1 Fable 5 vs GPT-5.1 DeepSeek R1 vs o3

Comparing o3 vs GPT-5.1 on price alone never tells the whole story — output-token weighting, context length, and your usage profile change the answer dramatically. Use the calculators below for the full picture.