---
title: "Exact model token count"
method: POST
path: "/count_tokens"
---

# Exact model token count

`POST /count_tokens`

## Request

- Base URL: `https://api.openmayhem.ai/v1`
- URL: `https://api.openmayhem.ai/v1/count_tokens`
- Auth: HTTP bearer

Alias of POST /tokenize. Supply exactly one of messages or prompt. This request is authenticated and rate-limited but never billed.

## Headers

- `X-Mayhem-Min-Att-Tier` union
  - integer
  - 'T1' | 'T2' | 'T3' | 'T4'
- `X-Mayhem-Min-Ctx` integer
- `X-Mayhem-Quant` string
- `X-Mayhem-Prefer-Providers` string
- `X-Mayhem-Hedge` 0 | 1
- `X-Mayhem-Min-Tok-S` number
- `X-Mayhem-Max-Wait-Ms` integer
- `X-OpenMayhem-Max-Cost-Usd` string: Non-negative decimal USD string with at most 6 decimal places, parsed with exact fixed-point arithmetic.
- `X-OpenMayhem-Max-Input-Price-Per-Million-Usd` string: Non-negative decimal USD string with at most 6 decimal places, parsed with exact fixed-point arithmetic.
- `X-OpenMayhem-Max-Output-Price-Per-Million-Usd` string: Non-negative decimal USD string with at most 6 decimal places, parsed with exact fixed-point arithmetic.
- `X-OpenMayhem-Max-Representative-Request-Price-Usd` string: Non-negative decimal USD string with at most 6 decimal places, parsed with exact fixed-point arithmetic.
- `X-OpenMayhem-Estimate` string

## Request body

- object
  - `model` string, required: Catalog model id (vendor/model).
  - `messages` object[]
  - `prompt` string
  - `return_tokens` boolean

## Response `200`

Exact tokenization response.

## Other responses

- `400`: Contract violation; nothing charged.
- `401`: Missing or invalid API key.
- `402`: Insufficient credit.
- `403`: Scope, allowlist, spend limit or account restriction.
- `429`: Rate limit; wait Retry-After seconds.
- `503`: No provider capacity; retry with backoff.

---

[API](https://skmtc.dev/openmayhem/apis/openmayhem-api.md) · [All operations](https://skmtc.dev/openmayhem/apis/openmayhem-api/llms.txt) · [OpenAPI document](https://skmtc.dev/openmayhem/apis/openmayhem-api/revisions/0ea33ad12f21?raw)