Layer height: what it changes and what it does not

By Tiehl Roberto Matías · 8 min read · Updated 26 October 2026

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Layer height is the first setting everybody touches when a piece does not come out as expected, and on a QR code it is the worst understood: it nearly always gets lowered to gain a detail that does not depend on it, and almost nobody looks at the one thing it does decide, which is whether the relief you chose can be printed as it stands.

What does not change: the detail of the code

Let us start by undoing the misunderstanding, because it is the one that wastes the most print hours. Lowering the layer height does not make the modules finer or better defined. Layer height is a vertical measurement: it says how thick each pancake of plastic the machine stacks is. Module size is horizontal, and something else decides that.

The horizontal is decided by the width of the bead coming out of the nozzle, which is roughly its diameter. That is why a module needs to fit two beads, and why with a 0.4 mm nozzle the minimum module is 0.8 mm: the full calculation is in the minimum size guide. That 0.8 is the same whether you print at 0.08 mm layers or at 0.30.

What does change: the relief comes in whole layers

Here is what this option really decides. The relief of the code is a short piece — between six tenths and a millimetre and a half — sitting on top of the base. And a filament printer cannot make half a level: the relief comes out as a whole number of layers. If the number does not come out round, the slicer rounds it on its own, and what you print is not what you chose.

The generator offers relief in steps of two tenths, from 0.4 to 2.4 mm. These are the values that land exactly on a layer multiple at each common height:

Layer height	Reliefs that come out exact	Out of eleven
0.10 mm	all of them	11
0.20 mm	all of them	11
0.08 mm	0.4 · 0.8 · 1.2 · 1.6 · 2.0 · 2.4	6
0.12 mm	0.6 · 1.2 · 1.8 · 2.4	4
0.15 mm	0.6 · 1.2 · 1.8 · 2.4	4
0.30 mm	0.6 · 1.2 · 1.8 · 2.4	4
0.16 mm	0.8 · 1.6 · 2.4	3
0.24 mm	1.2 · 2.4	2
0.25 mm	1.0 · 2.0	2
0.28 mm	1.4	1

At 0.10 and 0.20 mm any relief in the generator works, because they are all multiples of two tenths. At 0.28 only one fits in the whole scale.

When it does not fit, this is what comes out. The case of the 0.6 mm relief, which is the one to use on keychains and tags:

Layer height	Layers	Real relief
0.10 · 0.12 · 0.15 · 0.20 · 0.30 mm	6 · 5 · 4 · 3 · 2	0.60 mm exactly
0.08 mm	7 or 8	0.56 or 0.64 mm
0.16 mm	3 or 4	0.48 or 0.64 mm
0.24 mm	2 or 3	0.48 or 0.72 mm
0.25 mm	2 or 3	0.50 or 0.75 mm
0.28 mm	2 or 3	0.56 or 0.84 mm

Look at the first row: 0.30 mm, the thickest layer on the list, behaves better than 0.25 and than 0.28. It is not a question of fine or thick, but of whether it divides exactly. Two layers of 0.30 give 0.60 on the nose.

The band it has to fit into

A relief coming out at 0.56 instead of 0.60 sounds like a difference that does not matter. It stops sounding that way the moment you remember which two limits it has to fall between, set out in the relief guide:

• At the bottom, 0.6 mm. Any less and the colour of the code comes out so thin that the base shows through and the contrast drops.
• At the top, 70 % of the module. Any more and the relief itself hides the light modules as soon as the phone looks from the side.

On a large plate those two limits leave plenty of room. On a small piece they close in until they almost touch, and then the layer height decides whether there is any gap left to fit a whole number of layers into. With the reference code of these guides — a 49-character link, version 4, 33 modules a side — this is what comes out:

Piece	Module	Valid band	Layer heights that do not work
Keychain 40 mm	0.92 mm	0.60 – 0.64 mm	0.24 · 0.25 · 0.28
Keychain 50 mm	1.15 mm	0.60 – 0.80 mm	0.28
Stand 90 mm	2.04 mm	0.60 – 1.43 mm	none
Plate 90 mm	2.09 mm	0.60 – 1.46 mm	none
Plate 150 mm	3.49 mm	0.60 – 2.44 mm	none

«Does not work» means literally that: there is no whole number of layers that falls inside the band. On a 40 mm keychain printed at 0.28, two layers give 0.56 and fall under the contrast floor; three give 0.84 and go over the 0.64 ceiling. There is no option in between, because you cannot print a layer and a half.

On plates there is nothing to watch: the module is so large that the ceiling is miles up and any layer height finds room. The problem belongs to the small pieces, which are exactly the ones that get printed most.

A thick layer also forces a bigger piece

The sum can be turned round, and that gives the most useful result in this guide. If the lowest relief you can print at your layer height is n × layer, and that relief cannot exceed 70 % of the module, then your layer height is fixing a minimum module for you. And from that, a minimum size of piece.

Layer height	Lowest possible relief	Minimum module	Minimum piece
0.10 · 0.12 · 0.15 · 0.20 · 0.30 mm	0.60 mm	0.86 mm	36 mm
0.08 mm	0.64 mm (8 layers)	0.91 mm	38 mm
0.16 mm	0.64 mm (4 layers)	0.91 mm	38 mm
0.24 mm	0.72 mm (3 layers)	1.03 mm	43 mm
0.25 mm	0.75 mm (3 layers)	1.07 mm	44 mm
0.28 mm	0.84 mm (3 layers)	1.20 mm	50 mm

The right-hand column is the side of the piece for that 33-module code. Put another way: the same keychain that comes out fine at 36 mm printing at 0.20 needs 50 mm if you print it at 0.28. Thirty-nine per cent more piece for a setting chosen to go faster.

And there is something else worth seeing: with a 0.4 mm nozzle the minimum module on the nozzle side is 0.8 mm, but the one coming out of this table is 0.86 even in the best case. On small pieces it is not the nozzle in charge: it is the relief, and at 0.24 layers or more the difference stops being a detail.

The base, the colour change and the first layer

The base has the same problem, but with a different consequence: if your printer has a single extruder, the filament change has to land exactly where the base ends. If the base height does not give a whole number of layers, the change lands mid-layer and leaves a mixed band. That sum, with its table, is in the colour change guide, and the thicknesses the base guide recommends are chosen with this in mind too.

There is one trap neither of them covers, because it belongs to the profile rather than the piece: many profiles print the first layer thicker than the rest, so it grips the plate better. The moment that happens, the whole sum goes out. Every base thickness in the generator is a multiple of two tenths, so with 0.20 mm layers for the rest:

• First layer of 0.20 or 0.40 mm: the sum still gives a whole number.
• First layer of 0.25, 0.28 or 0.30 mm: no base thickness gives a whole number. With a 2 mm base and a 0.3 first layer you get 9.5 layers.

There is no need to do the sum by hand: the slicer shows the height of each layer as you move the cursor through the preview. Find it, check there is a layer starting exactly at your base height, and if there is not, set the first layer equal to the rest.

Which layer height to use

With all of the above, the recommendation writes itself and it is fairly boring:

Piece	Layer height	Why
Anything, by default	0.20 mm	Divides every relief and base exactly.
Keychain or tag	0.20 mm	The 0.6 relief is exactly three layers.
Plate or stand in a hurry	0.30 mm	Divides 0.6 and 1.2, and there the ceiling is miles up.
Finer finish to the eye	0.10 mm	Divides everything, but takes twice as long.
0.24 · 0.25 · 0.28 mm	Avoid on small pieces	They leave no valid relief below 50 mm.

The short rule, if you take only one thing away: use 0.20 mm and forget about it. It is the one that divides everything the generator offers exactly, in the base and in the relief, and it is the one the other guides take for granted when they say «0.6 mm is three layers».

If your fast profile uses another, nothing happens as long as the piece is large. Before launching a whole batch with it, do the thirty-second check: look in the slicer preview at what height the relief actually ends and compare it with the one you chose. It is one of the four tests in the testing guide, and here it catches a failure that is impossible to diagnose by eye on the finished piece.