3D Printing Calculators
Bottom / Burn-in Layer Exposure
https://www.3dsizing.com/calculators/bottom-layer-exposure/
Estimate only — not firmware, a slicer profile or a shop quote. Confirm on a test print.
Bottom / Burn-in Layer Exposure
Rafts stick when the first layers get several times the normal UV dose. Multiply normal exposure by your burn-in factor, then by how many bottom layers you run, to see how much of the job is just the base.
Inputs
Results
- Bottom exposure per layer
- 25.00s
- Total burn-in UV time
- 150.0s
- Multiplier used
- 10.00
Does not include lift, retract or wait times.
Calculation method
Bottom-layer exposure is normal exposure times the burn-in multiplier. Total UV time for the base is that bottom exposure times the number of bottom layers. The ratio output repeats the multiplier so you can confirm what went into the math. Times are seconds and do not convert with the imperial toggle. Invalid if any input is not positive.
Exact formula
bottom_s = normal_s × multiplier. total_bottom = bottom_s × bottom_layers. ratio echoes the multiplier. Limits: Multiplier is a starting guess. Too much welds the raft to FEP; too little drops the print in the vat.
Transition layers
Some slicers fade from burn-in to normal over a few layers. This calculator treats a hard step: N layers at full bottom exposure.
Frequently asked questions
Do I scale burn-in the same as normal exposure?
Usually less aggressively. If you cut normal time in half for a new mono screen, try 0.6–0.8× on the old burn-in, then test a raft.
How many bottom layers?
4–8 is common. Heavy hollows and small rafts may want more. Extra bottom layers add minutes and FEP wear.
Is total bottom time the print time?
No. Lifts, retracts and waits dominate resin print clocks. This is only the UV on the base.
FEP is new — same multiplier?
New FEP can need slightly less burn-in because release is easier and light is cleaner. Re-check adhesion rather than copying a two-year-old profile.
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