Variable layer height in PrusaSlicer: controls and checks explained

Distribute vertical detail

Variable layer height lets you use different layer heights in regions of the same model. You can generate an automatic profile, edit it manually or combine both methods. This guide is for readers who have already loaded an FDM/FFF model and know how to select a print profile.

The workflow and commands come from the official Prusa Research guide “Variable layer height function”, classified as PrusaSlicer 2.9 (Legacy). Some source images may come from earlier versions. We have not checked the current interface: compare this documented scope with your installation.

Choose a base profile and open the tool

Choose a profile close to the layer height expected for most of the model. A profile also changes other settings, such as extrusion width: it does more than select a height. Before changing the variable layer height profile, keep a reference of the initial preview and estimates for the final comparison.

Hypothetical teaching example: an object with a simple body and curved top. It can help you consider where to distribute different layers, but does not establish the preferred profile or any time saving.

1. Select the model in the 3D view: the variable layer height tool becomes available in the top toolbar.
2. Activate the tool. The official guide describes a contour preview, a window in the bottom right and a side panel for editing the profile.

Adaptive: recalculate after every Quality/Speed adjustment

Quality/Speed changes the proportion of thinner and taller layers. Adaptive calculates the profile from that choice; moving the slider alone is insufficient to display a recalculated profile. The source assigns no universal percentages to this trade-off.

1. Adjust Quality/Speed and press Adaptive to generate the profile.
2. If you move Quality/Speed again, press Adaptive again. Repeat this recalculation after every subsequent slider adjustment before assessing the profile.

Smooth and Keep min: smooth while preserving minima when needed

Smooth regularizes the variable layer height profile. A larger radius has a greater effect and the command can be repeated. Keep min preserves the minimum layer heights during this operation: select it if you want to retain those minima while smoothing the rest.

1. Consider where you want to smooth the profile and choose the Smooth radius.
2. Enable Keep min if you intend to preserve minimum layer heights, then apply Smooth. If you repeat the operation, review the resulting profile before making local edits.

Edit one region and understand shared changes

You can edit the automatic result or start directly with manual editing. Hovering over the side panel highlights the affected region in yellow. The gestures below are those documented by the source; no trackpad equivalents are inferred here.

Changes affect all instances of the same object. Check its copies: this does not mean every separate mesh on the plate is changed. The initial jump in the blue curve represents the first-layer setting; the official guide describes it as normal.

1. Use the left mouse button to add detail and the right button to reduce it in the indicated region.
2. Use Shift+left to restore the base height and Shift+right to smooth. The mouse wheel changes the width of the affected region.
3. To undo all automatic and manual variable layer height changes, use Reset.

Re-slice and check your own project

These are proposed checks, not results of our own experiment. To compare before and after, keep a reference of the initial project’s preview and estimates. After your adjustments, re-slice the project before comparing the new preview and estimates with that reference.

The source “Layers and perimeters” distinguishes the number of solid top/bottom layers from minimum thickness; it describes the usefulness of a minimum with variable layer height and a tooltip that updates the resulting thickness. Setting the number of top or bottom solid layers to zero overrides minimum thickness: a minimum alone does not guarantee closure.

1. Recheck instances of the same object and top/bottom settings, distinguishing layer count from minimum thickness.
2. Re-slice after your adjustments. Then compare your project’s preview and estimates and assess whether the trade-off meets your goal.
3. If the result looks suitable, consider a small test print before applying the choice to other jobs.

What a lower layer height does not establish

According to “Layers and perimeters”, layer height affects vertical Z resolution. In the official example, reducing it does not increase the XY resolution of raised text parallel to the bed. Do not infer an automatic fix for missing walls or guaranteed dimensional accuracy.

The documentation describes a potentially favorable trade-off between time and quality, rather than a guaranteed gain. We performed no slicing, local interface checks or physical prints for this guide. We provide no universal values, compatibility with every machine or material, measured savings or mechanical benefits. Adaptive infill is a different feature and is outside this procedure.