Flooring Calculator
Estimate how many boxes of laminate, vinyl plank, hardwood or tile you need, with a waste allowance, total flooring cost and underlayment rolls.
Flooring is sold in boxes that each cover a fixed area, so the job is to measure the floor, add a little for cuts and mistakes, and round up to whole boxes. This calculator does that for laminate, vinyl plank, engineered or solid hardwood and tile, in square feet or square meters. It also prices the boxes you will actually buy and counts underlayment rolls, and compares 5%, 10%, 15% and 20% waste so you can see what a diagonal layout costs.
How to use this tool
- Choose feet or meters and enter the room length and width.
- Add closets or a second part of an L-shaped room as extra area.
- Set the waste allowance for your layout.
- Enter the coverage per box and the price per square foot or meter.
- Enter the underlayment roll coverage, or 0 if you do not need it.
Formula
Boxes = ⌈(L × W + extra) × (1 + waste ÷ 100) ÷ coverage per box⌉
L and W are the room length and width, ⌈ ⌉ rounds up to a whole box, and cost = boxes × coverage per box × price per unit area, because you pay for every full box. Underlayment rolls use the same area including waste.
Example
A 15 ft × 12 ft living room is 180 sq ft. Adding 10% waste gives 198 sq ft. With boxes of 20 sq ft, 198 ÷ 20 = 9.9, so you buy 10 boxes, or 200 sq ft. At $3.50 per sq ft the flooring costs $700, and with underlayment rolls of 100 sq ft you need 2 rolls. Switching to a 15% allowance for a diagonal lay raises it to 207 sq ft and 11 boxes ($770).
Frequently asked questions
How much waste should I add for flooring?
Around 5–10% for planks laid straight in a simple rectangular room, and 15% or more for diagonal, herringbone or rooms with many corners. Check the manufacturer’s installation guide for your product.
Where do I measure from?
Measure wall to wall at floor level and round up to the next inch or centimeter. Include areas under door frames and inside closets that will get the same floor.
Why does the cost use full boxes?
Stores sell flooring by the box, so you pay for the whole box even if some planks are left over. The cost shown is boxes × coverage × price per unit area.
Should I keep the leftover boxes?
Keeping a few spare planks or an unopened box makes repairs easier, because later batches can differ slightly in color.
Last updated: 2026-10-30