THE MATH, MADE VISIBLE
How it works
Add the net areas of all rooms using the same product. Apply the allowance once to the total. Boxes = round up(adjusted area ÷ area per box). Cost = whole boxes × your price per box.
Real project examples
Two rooms, one product
12 × 10 ft plus 8 × 5 ft = 160 ft². With 10% extra, plan 176 ft². At 22 ft² per box, buy 8 boxes. At $50 per box, material cost is $400.
The cost of rounding each room separately
The same two rooms need 6 and 2 boxes respectively when rounded separately: 8 boxes total. With 20 ft² cartons, however, separate rounding gives 7 + 3 = 10 boxes, while pooling 176 ft² gives 9. At an entered $50 per box, pooling saves one $50 carton. Keep different products in separate orders.
Before you buy
- For an L-shaped room, split the floor into non-overlapping rectangles and add each with Add another room. Do not multiply the longest length by the widest width or count overlapping sections twice.
- This area-and-carton calculation works for laminate, vinyl plank and hardwood sold in boxes. Enter the coverage and allowance for the exact product; it does not design plank layouts.
- Combine rooms only when they use the same material and package coverage. Estimate different products separately.
- Read the carton’s coverage. Box quantity, plank dimensions and actual area vary by product.
- 10% is an editable planning assumption. Follow the manufacturer and installer for your pattern and geometry.
- Buy compatible batches and check return rules. Carpet and sheet goods require roll-width and seam planning beyond this boxed-flooring estimate.
Questions worth asking
How many boxes of flooring do I need?
Add each room length × width, subtract areas that will not receive flooring, multiply the net total by 1 + your allowance / 100, then divide by carton coverage and round up once. Use Price per box to calculate the actual whole-carton material cost.
How do I exclude a kitchen island or built-in cabinet?
Enter the measured footprint under Room excluded area in Product & allowance assumptions, only if the installation instructions say that area will not receive flooring. For example, a 12 × 10 ft room minus a 6 × 3 ft footprint leaves 102 ft²; with 10% extra and 22 ft² per box, order 6 boxes.
Why pool rooms before rounding?
If they share the same product, a partial box from one room can supply another. Rounding each room independently can buy unnecessary boxes.
What does leftover mean?
Package overage is purchased area minus your target including allowance. Total extra also includes the allowance itself; neither guarantees reusable full planks.
Does this calculate installation or adhesive cost?
No. Optional cost covers purchased boxes only. Use your installer and product guidance for other materials.
Sources & assumptions
NIST · unit conversion factorsPERGO · product-specific installation guidanceLast reviewed October 1, 2026. Planning defaults are editable examples. Product labels and supplier information override them.