---
title: "Calibrate Scale Region"
method: PATCH
path: "/api/v1/scale-regions/{region_id}/calibration"
tags: ["scale-regions"]
---

# Calibrate Scale Region

`PATCH /api/v1/scale-regions/{region_id}/calibration`

## Path parameters

- `region_id` string, uuid, required

## Request body

- UpdateScaleRegionCalibrationRequest — Set or update a region's calibration. Server computes `scale_ratio` from the embedded CalibrationData via the existing `compute_scale_ratio` and recomputes only this region's measurements, atomically (spec §5.3). Mirrors `UpdatePageCalibrationRequest`.
  - `calibration` CalibrationDataInput, required — User-entered calibration tuple, the shape stored in pages.calibration JSONB.
    - `drawing_distance` union, required
      - number
      - string
    - `drawing_units` 'in' | 'ft' | 'mm' | 'cm' | 'm', required
    - `actual_distance` union, required
      - number
      - string
    - `actual_units` 'in' | 'ft' | 'mm' | 'cm' | 'm', required
    - `source` 'standard' | 'manual' | 'calibrate', required
    - `description` string, required
  - `accepted_suggestion` boolean
  - `confirm_reduced_print` boolean

## Response `200`

Successful Response

- ScaleRegionMutationResponse — Returned by calibrate / edit / delete: the region (omitted on delete is out of scope — delete returns only the count) plus how many measurements were recomputed in the same transaction.
  - `region` ScaleRegion, required — A single rectangular scale region on a page. `scale_ratio` / `calibration` are None until the region is calibrated; an uncalibrated region is inert for scale resolution (spec §5.1).
    - `id` string, uuid, required
    - `project_id` string, uuid, required
    - `page_id` string, uuid, required
    - `name` string, required
    - `color` string, required
    - `x` string, required
    - `y` string, required
    - `width` string, required
    - `height` string, required
    - `scale_ratio` string, nullable
    - `calibration` CalibrationDataOutput — User-entered calibration tuple, the shape stored in pages.calibration JSONB.
      - `drawing_distance` string, required
      - `drawing_units` 'in' | 'ft' | 'mm' | 'cm' | 'm', required
      - `actual_distance` string, required
      - `actual_units` 'in' | 'ft' | 'mm' | 'cm' | 'm', required
      - `source` 'standard' | 'manual' | 'calibrate', required
      - `description` string, required
    - `created_at` string, date-time, required
    - `updated_at` string, date-time, required
    - `scale_source` 'autoset' | 'user' | 'import', required
    - `suggested_notation` string, nullable
    - `suggested_ratio` string, nullable
    - `prior_violated` boolean, nullable
  - `recomputed_measurement_count` integer, required

## Other responses

- `4XX` — Client Error
- `5XX` — Server Error

---

[API](https://skmtc.dev/rudus/apis/rudus-api.md) · [All operations](https://skmtc.dev/rudus/apis/rudus-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/rudus/rudus-api/revisions/5673f72c8a5d/schema)