Coverage Rate Calculator
Divide an area by how much one bag, gallon, roll, or box covers to get the number of units to buy — rounded up — plus how much your units will cover.
Bags, gallons, rolls, and boxes all come with a coverage rating — how much area one unit spreads over. To find how many units a job needs, divide the total area by that coverage rate. A `400` square foot job with a product that covers `32` square feet per unit needs `400 ÷ 32 = 12.5` units, which rounds up to `13` because you cannot buy half a bag. The calculator always rounds the purchase count up so you are never a fraction of a unit short.
It also runs the math the other way. Enter how much one unit covers and the calculator shows what your rounded-up count actually covers — `13` units at `32` square feet each blanket `416` square feet, a little more than the `400` you measured. That surplus is normal and useful: it absorbs spillage, uneven surfaces, and the odd miscut. Switch the toggle to enter area and coverage in square meters, and read the same unit count. Coverage ratings come from the product label, so use the manufacturer's number for the surface and conditions you actually have.
= 400 / 32 = 12.5 -> round up to 13 units
= 13 x 32 = 416 sq ft covered