Every 3D print is built from layers stacked one on top of another. How thick each layer is, the layer height, is one of the main things that decides how smooth a print looks and how long it takes. This guide explains the trade-off in plain terms, and what to do if your part needs a particular finish.
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Our instant quote does not ask you to choose a layer height. If your part needs a specific layer height or surface finish, email us before you order (see below).
What layer height is
An FDM printer builds a part by laying down a thin line of melted plastic, one layer at a time, then moving up and printing the next layer. The layer height is the thickness of each of those layers, usually a fraction of a millimetre.
A resin printer also builds in layers, curing a whole layer of liquid resin at once. Its layers are very thin, which is a large part of why resin prints look so smooth.
The trade-off: detail against time
Thinner layers
- Smoother curves and slopes. Every layer leaves a small step on the surface. Thinner layers mean smaller steps, so domes, faces and gentle slopes look smoother.
- Finer vertical detail. Small features such as raised text, ridges and edges on the side of a part come out crisper.
- Longer print times. A part twice as tall at the same layer height needs twice as many layers; halving the layer height also doubles the number of layers. More layers means more time on the printer.
Thicker layers
- Faster prints, which matters most on large or tall parts.
- More visible layer lines, especially on curved and sloped surfaces, which show a “staircase” effect.
- Less fine detail in the vertical direction.
Where layer height makes little difference
Layer height mostly affects surfaces that slope or curve. Straight vertical walls look similar at different layer heights, and flat tops and bottoms are not affected by it at all. So a boxy enclosure gains little from thin layers, while a figure or a rounded product gains a lot.
Layer height also has little to do with the price you see in our quote. PLA pricing is based mostly on the weight of plastic printed, which depends on size and infill; see our infill percentage guide.
How layer height interacts with size
- Small, detailed parts benefit most from fine layers, because each layer step is large compared with the features. For very small detailed parts, such as miniatures, resin is usually the better answer.
- Large parts hide layer lines naturally, because each step is tiny relative to the whole part, and viewers stand further back. Fine layers on a large part mainly add hours.
- Tall parts multiply everything. The number of layers rises with height, so a tall part at fine layers takes much longer than a short one.
Other ways to get a smoother finish
- Matte PLA scatters light instead of reflecting it off each layer, so layer lines are much less noticeable. See matte PLA 3D printing.
- Silk PLA does the opposite: its shine can make layer lines more visible on some shapes. See silk PLA 3D printing.
- Orientation. The direction a part is printed in decides which surfaces show layer steps. Our guide to designing for FDM covers this.
- Sanding and priming after printing. Our guide to post-processing 3D prints explains how.
How to ask us for a specific layer height
If your part needs a particular layer height or surface finish, email quotes@3dprinting.zone before you order. Include:
- the model file (STL, 3MF, OBJ or STEP),
- the layer height or finish you need, and why (for example, a visible curved face, fine text, or a part that must match another part),
- the material and colour, and how many you need.
We will let you know what we can do and whether it changes the price or timing. For most parts, the standard settings work well and you can simply order through the instant quote.
For a comparison of the materials we sell, see our 3D printing materials guide, and for how ordering works, our online 3D printing service.
Frequently asked questions
What layer height do you print at?
The instant quote does not offer a layer height choice. If your part needs a specific layer height, email quotes@3dprinting.zone before ordering and we will tell you what we can do.
Does a smaller layer height make a part stronger?
Not in any simple way. Layer height mainly affects surface finish and print time. For strength, infill, wall thickness and print orientation matter more; see the infill percentage guide.
Will I be able to see layer lines on my print?
On FDM prints, usually yes, if you look closely, especially on curved and sloped surfaces. Matte PLA makes them less noticeable, and resin prints show far less.
Is resin better than PLA for detail?
Yes, for small parts. Resin builds in very thin layers and gives a much smoother surface, but the build size is limited to 80 x 127 x 160 mm.
Can layer lines be removed after printing?
They can be reduced by sanding, priming and painting. See our guide to post-processing 3D prints.