Bed Mesh

Understand the surface4 sections

Reading a bed mesh

Read the surface, understand the numbers, and separate overall tilt from the shape that remains.

Start with the measured grid

A mesh records heights at sampled positions across your print bed. It describes the measurements your printer reported, including the effects of the probe and measurement setup. A smooth-looking chart alone does not establish the accuracy of those measurements.

Bed Mesh keeps the original row order. Hover a point or open View measured values to check it. Use Flip X or Flip Y to match the plot to your printer. If you enter dimensions, use the width and depth of the sampled area, which may be smaller than the bed.

Read the numbers together

Height range
The highest measurement minus the lowest. It captures the full spread, including isolated points.
Mean height
The signed average. It can change when the height reference changes between measurements.
Standard deviation
The spread around the mean, using every sampled value. It adds context to the two extremes.

The main statistics and exported CSV always use the original measurements. Display settings do not rewrite them.

Separate tilt from surface shape

The analysis fits a least-squares plane to the regularly spaced grid. Fitted X rise describes that plane's height change from the first column to the last; Fitted Y rise runs from the first row to the last. Their signs follow input order, so identify your printer's orientation before interpreting a direction.

Subtracting the plane leaves residuals: the variation that a simple overall slope cannot explain. Residual range is their full spread; residual RMS is their root-mean-square height around zero. A tilted, flat mesh can have a large original range and tiny residuals. A bowl can retain substantial residual variation.

Overall tilt and remaining curvature The left cross-section has five points on a straight tilted line. The right shows a separate bowed cross-section after fitted tilt removal, with its edges above zero and centre below zero. Height is exaggerated. Tilted, flat surface Original heights Bowed residual After fitted tilt removal Position across the sampled area Position across the sampled area 0
Two illustrative cross-sections. Removing overall tilt flattens a straight slope; curvature remains in a bowed surface. Height is exaggerated.

These are descriptions of the grid. They do not identify which component needs adjustment or calculate screw turns.

Choose a useful view

The 3D view exaggerates height to reveal variation. Use the heatmap for a view from above. Centre on mean and Remove fitted tilt change the displayed reference only. Return to Measured height whenever you want to inspect the original heights.