The resin exposure time calculator provides starting-point exposure times for MSLA and DLP resin printers. Select your resin type, layer height, and UV light source wavelength to get bottom layer and normal layer exposure times.
How Resin Exposure Times Work
Resin 3D printers (MSLA/SLA/DLP) cure photopolymer resin with UV light. The exposure time controls how long each layer is illuminated — too short and layers won't cure properly (under-cure), too long and fine details wash out (over-cure).
Bottom layers vs normal layers
Bottom layers (the first 4-6 layers) use significantly longer exposure times (10-30x longer) to ensure strong adhesion to the build plate. Normal layers use much shorter times optimized for detail and speed. Getting bottom layer exposure right is critical — too short causes print detachment mid-print.
Calibration prints
Use an exposure matrix (sometimes called a "resin calibration lattice" or "Cones of Calibration") to find exact exposure times for your specific printer and resin. These test prints vary exposure across a single print so you can identify the optimal time visually. Most resin printer communities have calibration files available for free download.
Why times vary by wavelength
Different UV wavelengths cure resin at different rates. 365nm UV cures most resins faster than 405nm because photopolymers have higher absorption at shorter wavelengths. High-power DLP projectors at 365nm can achieve 1-2 second layer times. Consumer MSLA printers at 405nm typically need 2-6 seconds per layer.
FAQ
Why do bottom layers need longer exposure?
Bottom layers need 10-30x longer exposure than normal layers to cure deep into the resin and bond strongly to the build plate or supports. Insufficient bottom layer exposure is the #1 cause of print detachment mid-print. Most printers use 4-6 bottom layers.
How do I know if my exposure time is correct?
Under-exposure: layers won't stick together, supports fail, fine features are missing. Over-exposure: detail is lost, holes fill in, text becomes unreadable. Run an exposure matrix test print — it tests multiple exposure times in one print so you can identify the optimal visually.
What wavelength does my resin printer use?
Most consumer MSLA printers (Elegoo Mars, Anycubic Photon) use 405nm mono LCD screens. Some newer Anycubic models use 385nm. DLP projectors vary — check your printer's spec sheet. Higher-power printers using shorter wavelengths (365nm) cure resin much faster.
Does layer height affect exposure time?
Yes — thicker layers require longer exposure to cure all the way through. The relationship isn't linear; a rough square root approximation applies. 0.1mm layers need roughly 40% more exposure than 0.05mm layers.
Is this calculator free?
Yes, completely free and no signup required.