Curing isn't a fixed number of seconds; it's a target amount of energy. Our free Curing Time Calculator turns your light's measured irradiance and your material's requirement into a defensible exposure time. Learn the principle below, then run the numbers.
A cure is governed by how much energy the material receives, radiant exposure, not by the clock alone. Two of these three numbers set the third.
Radiant exposure
J/cm² · the dose
=
Irradiance
mW/cm² · your light
×
Time
seconds · your choice
Irradiance
mW/cm²
How much light power your unit delivers per unit area, at the distance the restoration actually sits. It is not the number on the box: tip wear, distance, and angle all pull it down.
Exposure time
seconds
How long the light is held on the surface. The one variable most operators change by feel, and the one a calculator lets you set on purpose.
Radiant exposure
J/cm²
Irradiance × time. The total energy the material receives, and what actually drives the cure. On the Bluelight scale, an adhesive needs about 5 J/cm², a composite about 10, and a bulk-fill increment about 16.
Why it isn't just a number on a chart
Reciprocity, and where the physics stops cooperating.
Halve the irradiance and you'd expect to double the time to land the same dose. That's the reciprocity principle, and it holds across a useful range. But it breaks down at the extremes: very high irradiance over very short times doesn't fully substitute for adequate exposure, and a weak light can't always be rescued by simply curing longer.
That's why a generic "20 seconds" recommendation is a guess. The only way to set a defensible time is to start from your light's measured output and your material's requirement.
The tool
Curing Time Calculator.
Enter your light's measured irradiance, choose what you're curing, and get a target exposure time. Free, no account required.
What are you curing?
Recommended exposure
10seconds
To deliver 10 J/cm² to composite at 1,200 mW/cm². The restorative workhorse dose, per layer.
DeliveredMetShortfallJ/cm² · the energy a material needs vs. delivered. Synthetic data.
time = 1000 × required energy ÷ irradiance, rounded up to 5 s · for a verified number, measure with CheckUp or CheckMARC
A guide built on the Bluelight energy model and 1,300+ catalogued materials. It assumes the irradiance you enter is accurate, which is exactly the catch.
The catch
A calculated time is only as good as the irradiance you put into it.
Every number above hinges on one input you probably haven't measured: what your light actually delivers, today, at the working distance, not its rating when it was new.
In measured clinics, roughly 37.5% of cures fail to hit target before any training. The lights look fine. The output isn't. A calculator can't see that; a measurement can.
That's what CheckMARC does: we measure every light and every operator in your clinic, then hand back the real numbers to feed into a calculation like this one.
Request a CheckMARC evaluation: a partner visits, measures every light and operator, and you get the real per-light, per-operator numbers behind every cure.
