---
tag: m0421
title: Set Mesh Value
brief: Set a single mesh Z height
author: thinkyhead

requires: AUTO_BED_LEVELING_(BILINEAR|UBL)|MESH_BED_LEVELING
group: motion

related: [ G29, M420 ]
codes: [ M421 ]

notes:

parameters:
  -
    tag: I
    optional: true
    description: X index into the mesh array
    values:
      -
        type: int
  -
    tag: J
    optional: true
    description: Y index into the mesh array
    values:
      -
        type: int
  -
    tag: X
    optional: true
    description: X position (which should be very close to a grid line) (`MESH_BED_LEVELING` only)
    values:
      -
        tag: linear
        type: float
  -
    tag: Y
    optional: true
    description: Y position (which should be very close to a grid line) (`MESH_BED_LEVELING` only)
    values:
      -
        tag: linear
        type: float
  -
    tag: Z
    optional: true
    description: The new Z value to set
    values:
      -
        tag: linear
        type: float
  -
    tag: Q
    optional: true
    description: A value to add to the existing Z value
    values:
      -
        tag: linear
        type: float
  -
    tag: C
    optional: true
    description: Set the mesh point closest to the current nozzle position (`AUTO_BED_LEVELING_UBL` only)
    values:
      -
        type: bool
  -
    tag: N
    optional: true
    description: Set the mesh point to undefined (`AUTO_BED_LEVELING_UBL` only)
    values:
      -
        type: bool

examples:
  -
    pre: Set the Z height in the middle of a 5x5 grid
    code: M421 I2 J2 Z-0.05
  -
    pre: Set the same Z height using XY
    code: M421 X100 Y100 Z-0.05
  -
    pre: Adjust the mesh point by -0.01
    code: M421 I2 J2 Q-0.01

---

This command is used to set a single Z value for a mesh point in the stored bed leveling data.

Allowed forms are `M421 In Jn Zn`, `M421 Xn Yn Zn` (`MESH_BED_LEVELING` only) or `M421 C Zn` (`AUTO_BED_LEVELING_UBL` only).