When should I use a raft?

Use a raft when printing with warpy materials like ABS or Nylon, when your part has a very small footprint, or when bed adhesion is unreliable. For PLA on a good surface, a brim is usually sufficient.

How many raft layers should I use?

Two to three layers is standard. The base layer provides adhesion, and interface layers create a smooth surface for the part. More layers can help on uneven beds but waste more material.

How do I separate the raft cleanly?

Raft separation depends on the air gap setting in your slicer (typically 0.1-0.3mm; Cura default is 0.3mm, and a good starting point is about half the nozzle diameter — ~0.2mm for a 0.4mm nozzle). Let the part cool completely, then flex or peel the raft away. A larger air gap makes removal easier but may give a rougher bottom surface.

3DPrintCalcs

Raft Calculator — Extra Material & Time

Estimate extra material and time for raft adhesion layers.

Part Width (X)

Footprint width of the part on the bed (longest dimension along X)

Part Depth (Y)

Footprint depth of the part on the bed (longest dimension along Y)

Raft Margin

Extra area around the part

Raft LayersTotal raft layers (1 base layer + interface layers); 2-3 is standard

Material DensityFilament material — sets the density used to convert raft volume to weight

How We Calculate This

Formula

Raft dimensions = Part dimensions + 2 x Margin (margin is added on each side of the part)
Base layer volume = Raft area x Base Layer Height x Base Infill Fraction (defaults 0.3mm x 60%)
Interface volume = Raft area x Interface Layer Height x 90% density x (Raft Layers - 1) (default 0.2mm)
Raft weight = Total volume x Material density

The base layer uses a thicker layer height with gaps for easy removal. Interface layers are denser to create a smooth surface for the part to print on. Change the advanced inputs and the calculation tracks your values — the figures shown above are the defaults.

Frequently Asked Questions

Related Calculators

Bed Levelling Calculator

Calculate mesh bed levelling points and spacing for your build plate size.

Build Plate Calculator

Work out how many copies of a part fit on your build plate with spacing.

Adhesion Calculator

Estimate the contact area and adhesion force for your print footprint.

Brim Width Calculator

Calculate optimal brim width based on part footprint and material shrinkage.

Bed Temperature Calculator

Find recommended bed temperatures for different materials and surfaces.

Last updated: February 2026

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