Resin Exposure Time Calculator
Turn your resin's Dp and Ec, your light intensity and your layer height into a starting exposure time, a bottom-layer time and a total print estimate, with the working curve reacting live
Resin & Printer Settings
Resin and light
Use 100% if you measured the intensity recently; lower it if the screen or LEDs have aged
Layers
Lift and retract
A starting point: confirm with a test print
- Suggested test range
- 3.1 – 4.9 s
- Cure depth target
- 100 µm
Numbers look consistent. Print a small calibration model first and adjust in 10–20% steps.
Working curve: cure depth vs exposure time
The curve flattens as exposure grows: each extra bit of cure depth costs more light
How to use this tool
- Enter your resin's penetration depth Dp (mm) and critical energy Ec (mJ/cm²) from its datasheet.
- Enter the light intensity measured at the plate, adjust the remaining light-source power, and pick the layer thickness and cure-depth target.
- Fill in print height, bottom layers and multiplier, and the lift and retract distances and speeds.
- Read the normal and bottom exposure times, the energy dose and the total print estimate, then confirm with a small test print.
Worked example
With Dp = 0.15 mm, Ec = 8 mJ/cm², 4 mW/cm² at the plate and 0.05 mm layers at a 2× target, the cure depth is 0.10 mm. The working curve Cd = Dp · ln(E/Ec) solves to t = Ec · e^(Cd/Dp) / P = 8 · e^0.667 / 4 ≈ 3.9 s, a dose of 15.6 mJ/cm². An 8× bottom multiplier makes the bottom layers 31.2 s. A 40 mm print is 800 layers, and with a 6 mm lift at 60 mm/min and retract at 150 mm/min each layer spends 8.4 s moving, for a total near 2 h 46 min. The result is a starting point, not an exact value: resin batch, temperature and lens or screen age shift the real value, so calibrate in 10–20% steps.
Why this tool exists and where its numbers come from
Resin printers need an exposure time that matches a resin's cure behavior. The tool applies the working-curve equation to the values you enter, plus rules of thumb for overcure. The sources below define the equation and its terms; they do not give exposure times for any particular resin or printer, so always follow the resin maker's data sheet and safety guidance.
Sources
- Kolibaba et al., Results of an Interlaboratory Study on the Working Curve in Vat Photopolymerization (preprint, Additive Manufacturing)
- 3DResyns: Fundamentals of stereolithography (working curve model)
For the full method, see the Methodology section just below.
Methodology
Resin printers cure each layer with UV light, and the cured thickness follows a logarithmic law rather than a straight line. This calculator applies the working curve from stereolithography and a simple motion-time model so you can set a starting exposure for your own resin.
Marta's tired screen: when the light fades to 70%
Marta prints a 30 mm figure in 0.05 mm layers. Her resin sheet lists Dp = 0.12 mm and Ec = 6 mJ/cm². The printer is rated 5 mW/cm², but the screen has seen many hours, so she sets the remaining power to 70%. Lift is 5 mm at 60 mm/min, retract 180 mm/min, 6 bottom layers at 8×, cure depth target 2×.
- Effective intensity: 5 × 0.70 = 3.5 mW/cm².
- Cure depth target: 0.05 × 2 = 0.10 mm, so the dose is 6 · e^(0.10/0.12) = 13.8 mJ/cm².
- Normal exposure: 13.8 ÷ 3.5 = 3.9 s; bottom layers 8× = 31.6 s; suggested test range 3.2 – 4.9 s.
- 30 mm ÷ 0.05 mm = 600 layers, each adding 6.7 s of lift and retract. Total: 1 h 49 min, about 61% of it motion.
If she had left the slider at 100%, the tool would say 2.8 s and 1 h 36 min. On her worn screen that exposure would deliver only about 9.7 mJ/cm², a cure depth near 57 µm instead of 100 µm, barely above the layer height. So she starts a small calibration print at 3.2 – 4.9 s. This is an estimate, not a guarantee: resin batch and temperature still matter.
Resin Printing Essentials
Resin, post-processing and safety gear to match your calculation
SUNLU ABS-Like 3D Printer Resin 2 kg, Gray (405 nm, for LCD/DLP/SLA Printers)
ABS-like 405 nm photopolymer resin: less brittle than standard resin, with low shrinkage, for 2K to 8K LCD, DLP and SLA printers.
Anycubic Wash & Cure 3 Station with Gooseneck Lights (2-in-1)
2-in-1 wash and cure station for the Photon Mono 4/4 Ultra and Mars series, with a 165 × 100 × 180 mm washing size.
Disposable Black Nitrile Gloves, 6-mil, Heavy Duty (Latex Free)
Latex-free 6-mil nitrile gloves that protect your skin when handling uncured resin.
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Frequently asked questions
How do I find Dp and Ec for my resin? ▼
Some manufacturers publish them on the technical datasheet. If yours does not, measure them: print a cure-depth test at three or more exposure times, plot cure depth against the logarithm of the dose, and the slope is Dp while the point where Cd = 0 gives Ec. Until then, the defaults here (Dp 0.15 mm, Ec 8 mJ/cm²) are only a placeholder.
Why doesn't doubling the exposure double the cure depth? ▼
Because the working curve is logarithmic. Doubling the dose adds only Dp × ln 2, about 0.69 × Dp. With Dp = 0.15 mm that is roughly 0.10 mm more depth. This is why overexposing “just in case” mostly blurs detail instead of adding strength.
Why do bottom layers need much longer exposure? ▼
The first layers must bond to the build plate against peel force, with no layer below them. Slicers multiply the normal exposure for those layers; this tool uses a multiplier you set (5× to 10× is a common starting range) and shows what it does to total time. Too long and the first layers bloom (elephant foot).
How much of my print time is exposure versus lift? ▼
On many 0.05 mm prints the lift and retract motion takes longer than the light. With this calculator's defaults, about two thirds of the time goes to motion. Reducing lift distance or raising speeds often saves more time than shortening exposure, but peel force rises, so change one value at a time.