How do I find the correct exposure time?

Start with the manufacturer recommended time and print an exposure test (like the Resin XP2 validation matrix or AMERALABS town). Adjust in 0.2-0.3s increments. Under-exposure causes layer separation; over-exposure causes loss of detail.

Why do bottom layers need longer exposure?

Bottom layers need extra exposure to create a strong bond to the build plate. A common rule of thumb is 8-15x the normal time, but the exact ratio depends on your layer height: it is largest at the thinnest layer heights and decreases steadily as the layer height increases, so always read the actual bottom time this calculator gives rather than relying on a fixed multiple. Too little bottom exposure makes the print detach and fail; too much causes elephant foot (an enlarged, flared base).

What is the difference between mono and RGB screens?

Monochrome (mono) LCD screens transmit far more 405nm UV than older RGB screens — roughly 6% versus 1% — so they need much shorter exposure. In practice mono is about 4-8x faster: a resin needing ~2s on mono can need 8-16s on RGB (Liqcreate measured 2.0s mono vs 16.0s for the same resin on an RGB panel). Mono screens also last several times longer per panel. Almost all printers sold today are mono; if you have an RGB panel, calibrate carefully because transmission varies between models.

Does layer height affect exposure time?

Yes, thicker layers need proportionally more exposure. 0.05mm layers need roughly half the exposure of 0.1mm layers. The UV light must penetrate and cure the full depth of each layer.

Exposure Time Calculator

Exposure Time Calculator — Layer Exposure Settings

Calculate layer exposure time based on resin type, layer height and UV power.

Resin TypeSelect a resin type or choose Custom to enter a base exposure time

Layer Height

Height of each printed layer

Screen TypeMono LCD transmits ~6% of UV vs ~1% for older RGB, so RGB needs roughly 4-8x longer exposure. Almost all current printers are mono.

UV PowerMost mSLA UV arrays sit around 2-8 mW/cm². A higher-irradiance array cures resin faster, so it shortens the exposure time needed.

How We Calculate This

Exposure Time Formulas

Normal exposure = Base time x Screen multiplier x Layer factor x Power factor
Bottom exposure = Base bottom time x Screen multiplier x Bottom-layer factor x Power factor
Layer factor = Your layer height / 0.05mm (reference)
Bottom-layer factor = 1 + (Layer factor − 1) × 0.5 (a damped layer factor, since bottom layers are already heavily over-exposed for adhesion)
Screen multiplier = 1.0 for mono LCD, ~4.0 for older RGB LCD (RGB transmits far less UV)

The layer factor scales exposure linearly with thickness. The true physics follows the exponential Jacobs working curve (cure depth Cd = Dp × ln(E/Ec), so dose E rises exponentially with thickness). The linear factor over-estimates the dose needed for thick layers, which is the safe/conservative direction, and is accurate enough as a starting point across the usual 0.01-0.15mm range.

These are starting point estimates. Every resin, printer, and screen combination is different. Always run an exposure calibration test for your specific setup (such as the AMERALABS Town print or your printer's built-in RERF/R_E_R_F file). Adjust in small increments (0.2-0.5s) for fine-tuning.

Frequently Asked Questions

Last updated: February 2026

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

Exposure Time Calculator — Layer Exposure Settings

How We Calculate This

Exposure Time Formulas

Frequently Asked Questions

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