What is minimum layer time?

The shortest time a layer should take before the next layer starts. If a layer prints too fast, the previous layer has not cooled enough and will deform. Most slicers default to 8-15 seconds.

When should I use 100% fan?

PLA prints benefit from 100% fan for overhangs and bridges. For PETG reduce to 30-50%. For ABS and ASA, use minimal or no fan to prevent warping.

Why do small prints curl?

Small layers complete very quickly, giving no time for the plastic to cool and solidify before the next layer is deposited. Enable minimum layer time in your slicer to automatically slow down.

3DPrintCalcs

Cooling Calculator — Layer Time & Fan Speed

Estimate minimum layer time and fan speed for proper cooling of small parts and overhangs.

Total Path Length per Layer

Total extrusion path printed on a single layer (perimeters + infill). Find it in your slicer's per-layer print info, or estimate the part outline length.

Print Speed

Average print-head speed for this layer, in mm/s (your slicer's outer/inner wall speed for small parts).

How We Calculate This

Calculation

Layer time = Total path length per layer ÷ Print speed (mm ÷ mm/s = seconds).
This is a quick estimate from extrusion moves only. Real slicer layer time is a little longer because it also includes travel moves and the time lost to acceleration/deceleration, so treat the result as a lower bound.
If layer time is below the minimum (Cura defaults to 10 s; PrusaSlicer slows down below ~8 s for PLA, ~9 s for PETG, ~20 s for ABS), the slicer scales the print speed down — or lifts the nozzle — so the previous layer has time to solidify.
Fan-speed guidance is for PLA and uses simple layer-time bands. Real slicers interpolate the fan continuously between a "minimum fan speed at" and "maximum fan speed at" layer time rather than stepping. For PETG use roughly 30–50%, and for ABS/ASA keep the part fan off (or low, only over overhangs) to avoid warping and cracking.

Frequently Asked Questions

Related Calculators

Print Time Estimator

Estimate total print time from layer count, speed and travel moves.

Print Speed Calculator

Calculate maximum print speed based on volumetric flow rate and layer dimensions.

Infill Calculator

Estimate material usage and print time for different infill percentages and patterns.

Flow Rate Calculator

Calculate volumetric flow rate from print speed, layer height and line width.

First Layer Calculator

Calculate optimal first layer height, width and speed for strong bed adhesion.

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Last updated: February 2026

All calculations are estimates. Always verify settings with test prints before committing to final prints.