Budgeting the migration
OpenAI's named replacement for o1 is GPT-5.5, priced at $5 input / $30 output per MTok (verified 2026-09-07). What common volumes cost at those rates, assuming a 75% input / 25% output token split, before caching or batch discounts:
| Volume | Split | Cost at GPT-5.5 rates |
|---|---|---|
| 100K tokens in a day | 75,000 in + 25,000 out | $1.12 |
| That pace over a 30-day month (3M tokens) | 2.25M in + 750K out | $33.75 |
| 1M tokens in a month | 750,000 in + 250,000 out | $11.25 |
| Heavy month — 12M tokens | 9M in + 3M out | $135 |
Token counts are not portable across model families — tokenizers differ — so treat these as rate-card numbers and re-measure with your own payloads after migrating.
Frequently asked questions
When does o1 shut down?
OpenAI has scheduled o1 for shutdown on 2026-10-23. Shutdown 2026-10-23 → migrate to GPT-5.5.
What replaces o1?
The named migration target is GPT-5.5, currently priced at $5 per 1M input tokens and $30 per 1M output tokens (verified 2026-09-07).
What will GPT-5.5 cost to run?
At GPT-5.5 rates, 100K tokens a day (75% input / 25% output) costs about $1.12 — roughly $33.75 over a 30-day month — and 1M input + 1M output tokens together cost $35. Straight rate-card math; token counts differ between model families, so re-measure with real payloads.
Why is no price listed for o1?
We publish only prices verified against the provider's official pricing page, and OpenAI's pricing page no longer lists current rates for o1 — so this page tracks its status, shutdown date and migration path instead.