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First Layer Test Generator: One-Layer STL for Your Bed

Type your bed size and first layer height, pick a pattern, and download a one-layer test that covers the bed. Print it and compare the lines with the table: round, gappy lines mean the nozzle is too high, rough and see-through ones mean it is too low. Adjust the Z offset and print again.

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How to use a first layer test

  1. 1

    Enter your bed

    Type the bed width and depth (or pick a common size) and the first layer height you use. Keep the pattern a little inside the edge, away from the clips.

  2. 2

    Pick a pattern

    Rings and the solid pad cover the whole bed, five squares compare the corners and the centre, and lines make it easy to see gaps.

  3. 3

    Print and watch

    Slice with the first layer height you entered and your normal speed and temperature. Watch the first minutes: you can change the Z offset while it prints.

  4. 4

    Adjust the Z offset

    Make the lines slightly squished and joined. Nudge the nozzle down in 0.02 mm steps if they are gappy, up if they are rough, and print again.

Too high, good or too low

Look at the lines from above and touch the surface. The right squish is a small change: steps of 0.02 mm are often enough.

Too highThe lines are round and have gaps between them, or they do not stick and curl up or drag. Move the nozzle closer: Z offset lower by 0.02 to 0.05 mm.
GoodThe lines are slightly flattened, touch each other with no gaps, and the surface feels smooth. The sheet peels off whole.
Slightly lowThe surface is smooth but has ridges at the edges of the lines, and may be hard to remove. Raise the Z offset by 0.01 to 0.02 mm.
Too lowThe surface is rough or see-through, with ridges, or the extruder clicks as it pushes against the bed. Move the nozzle away: Z offset higher by 0.03 to 0.05 mm.
One area differentIf only a corner or the middle is off, the bed is tilted or warped. Level the bed (see the bed level test) before changing the Z offset.
Live adjustMarlin: M290 Z-0.02 moves closer. Klipper: SET_GCODE_OFFSET Z_ADJUST=-0.02 MOVE=1. A negative number brings the nozzle closer to the bed.

Why the first layer matters

The first layer is the only part of a print that has to stick to the bed, and every layer after it is built on top. If it is printed too high, the lines only touch the bed at one point and the print comes loose. If it is printed too low, the plastic is squashed out sideways, the surface goes rough and the bottom edge flares into an elephant foot.

The distance between the nozzle and the bed is set by the Z offset. A good first layer is slightly flattened: wide enough that the lines fuse into one sheet, without piling up at the sides. This test gives you a large, plain area to judge that by eye, instead of a small part where you cannot see what is wrong.

Squish also depends on the first layer height, the line width, the flow and the temperature, but the Z offset is the one to change first and the quickest to fix.

Level first, then set the Z offset

If the bed is not level, no single Z offset is right for the whole bed: one side will be too high while the other is too low. Print the bed level test first. It puts thin squares in the corners and the centre so you can see which knob to turn. This page is for the next step, once the bed is level and you want the offset to be right across the whole surface.

Choose rings or the pad to check that the first layer is even across the bed. Choose five squares to compare the corners with the centre. Choose lines to find the exact offset, because gaps between lines are the easiest thing to see.

A cold nozzle and a cold bed can both be a little different from a hot one. Heat both to printing temperature and let the printer sit for a few minutes before you judge. If you use auto bed levelling, run it before the test, and save the Z offset (M500 in Marlin) when you are happy with the result.

Good first layer? Print your own design

Now that prints stick, turn a picture or a description into something you can print.

Turn an image into an STL →Make a 3D model from text3D print ideas

More calibration tools

3D Printer CalibrationBed level test generatorE-steps calculatorFlow rate calculatorTemperature tower generatorCalibration cube generatorRetraction test generator

First layer test FAQ

A flat, one-layer print that covers a large part of the bed. Because it is just one layer, you can see and feel exactly how the plastic is laid down and whether the nozzle height (Z offset) is right.
Lines that are slightly flattened and fused with their neighbours, with no gaps and no ridges at the sides, and a smooth surface. It should peel off the bed as one sheet.
Change the Z offset in small steps of 0.02 mm. If the lines are round with gaps, move the nozzle closer. If the surface is rough or the extruder clicks, move it away. Print the test again after each change.
Use the one in your slicer profile, often 0.2 to 0.3 mm. Enter it here so the test is the same thickness as your real first layer. A slightly thicker first layer is more forgiving of an uneven bed.
Concentric squares (rings) cover the bed and are good for a general check. Five squares compare the corners and the centre. Lines suit tuning the Z offset. The solid pad is the most demanding, and shows everything at once.
The bed is tilted or warped. Level the bed with the bed level test, or use mesh bed levelling, and then set the Z offset. A Z offset cannot fix a bed that is not flat.
Yes. Run the levelling first and then print the test. If the whole test looks the same but is too high or too low, change the Z offset. If one area differs, check the probe offset and the mesh.
No. The model is built in your browser and downloaded straight to your device. It is free, with no signup and no upload.

The STL holds the exact sizes you set. Keep your hands and tools clear of the hot nozzle and bed while you adjust the Z offset, and change it in small steps.