What is cure depth and why does it matter?

Cure depth is how deep the UV light polymerises the resin in one exposure. It must be deeper than the layer height so each new layer bonds to the one below. Typically, cure depth should be 1.5-2x the layer height.

What is the Jacobs equation?

The Jacobs equation (Cd = Dp x ln(E/Ec)) describes how deep UV light cures into resin. Dp is the penetration depth (material property), E is the energy dose, and Ec is the critical energy needed to start curing. It is the fundamental equation of SLA printing.

How do I find my printer UV intensity?

Check your printer specifications for UV power density in mW/cm². Typical values: budget printers 8-12 mW/cm², mid-range 12-18 mW/cm², high-end 18-30 mW/cm². You can also measure with a UV radiometer.

What happens with too much over-cure?

Over-curing causes the light to bleed past the intended layer boundary, curing resin that should remain liquid. This results in loss of fine detail, thicker features than designed, and can cause hollow parts to cure solid if the walls are thin.

3DPrintCalcs

Layer Cure Calculator — Cure Depth & Energy Dose

Determine optimal cure depth and exposure energy for each resin layer.

Layer Height

Exposure Time

UV Intensity

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Resin Type

How We Calculate This

Layer Cure Formulas (Jacobs Equation)

Energy dose = UV intensity (mW/cm²) x Exposure time (s) = mJ/cm²
Cure depth = Dp x ln(E / Ec)
Over-cure = Cure depth - Layer height
Penetration ratio = Cure depth / Layer height

Dp is the resin penetration depth and Ec is the critical energy threshold. Both are material properties that vary by resin type. The ideal penetration ratio is 1.5-2.0x the layer height for good inter-layer bonding without excessive over-cure.

Frequently Asked Questions

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Last updated: February 2026

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