How Much Flooring or Tile Do You Need?

Buying flooring or tile is one of those jobs where running short mid-project is a real headache, because a fresh batch may not match, while over-buying wastes money. Working out how much flooring you need protects you from both. The method is simple: find the room’s area, add a margin for cutting waste, then divide by how much each box covers. This guide walks through the calculation with a worked example, explains how much waste to allow for different patterns, and shows how to handle multiple rooms. For measuring unusual rooms, our area calculator is a handy companion. It works the same for laminate, wood, vinyl, and tile.

The three steps

1. Calculate the room area: length times width.
2. Add a waste margin, usually 10%, for cuts and mistakes.
3. Divide by the area each box covers, then round up to whole boxes.

A worked example

Suppose your room is 12 feet by 10 feet, and each box of flooring covers 20 square feet.

1. Room area: 12 x 10 = 120 square feet.
2. Add 10% waste: 120 x 1.10 = 132 square feet.
3. Boxes needed: 132 / 20 = 6.6, so round up to 7 boxes.

In plain English: a 120 square foot room needs about 132 square feet of flooring once waste is included, which is 7 boxes at 20 square feet each. Always round up, since you cannot buy part of a box.

Measure the room first

Start by finding the room area. Our guide on how to calculate square footage shows how, and our area calculator handles rooms that are not simple rectangles.

How much waste to add

The waste margin covers offcuts, mistakes, and future repairs. How much to add depends on the layout:

• Simple straight layout: add about 5 to 10%.
• Diagonal or patterned layouts: add 15% or more, as angled cuts create more offcuts.
• Rooms with many corners or obstacles: lean toward the higher end.

It is also wise to keep a spare box after the job for future repairs, so the replacement matches your batch.

Multiple rooms

For several rooms with the same flooring, calculate each room’s area, add them together for the total, then apply the waste margin to the combined figure. Finally, divide by the coverage per box. Adding the areas first, before the waste and box calculation, gives a more efficient total than working out each room separately and rounding up several times.

Practical tips

• Check the box coverage carefully; it varies between products and is printed on the packaging.
• Buy all your flooring in one order so it comes from the same batch and matches.
• Measure twice before ordering, as flooring is expensive to get wrong.
• Account for thresholds and doorways if the flooring extends into them.

Frequently asked questions

How much flooring do I need?

Calculate the room area by multiplying length by width, then add about 10% for cutting waste. For a 120 square foot room, that is roughly 132 square feet. Divide this by the area each box covers and round up to find how many boxes to buy. Add more waste for diagonal or patterned layouts.

How much extra flooring should I buy for waste?

Add about 5 to 10% for a simple straight layout, and 15% or more for diagonal or patterned installations, which produce more offcuts. Rooms with many corners or obstacles also warrant a higher margin. It is also worth keeping one spare box after the job so any future repairs match your original batch.

How do I calculate how many boxes of flooring to buy?

Work out the total area you need including waste, then divide by the coverage per box printed on the packaging, and round up to the next whole box. For 132 square feet needed and boxes covering 20 square feet each, that is 132 divided by 20, which is 6.6, so you buy 7 boxes.

Is calculating tile the same as flooring?

Yes, the method is identical: find the area, add a waste margin, and divide by the coverage per box or the number of tiles per box. Tile often warrants a slightly higher waste allowance, around 10 to 15%, because tiles can crack and patterned or diagonal layouts create more cuts. Always round up.

How do I calculate flooring for multiple rooms?

Calculate each room’s area, add them together for a combined total, then apply the waste margin to that total and divide by the coverage per box. Adding the areas first is more efficient than rounding each room up separately, since offcuts from one room can sometimes be used in another.

The bottom line

To find how much flooring you need, calculate the room area, add roughly 10% for waste (more for diagonal or patterned layouts), then divide by the coverage per box and round up. A 120 square foot room needs about 132 square feet, or 7 boxes at 20 square feet each. Buy in one batch and keep a spare box. Measure unusual rooms with our area calculator.

Further reading

For authoritative background on this topic, see Flooring on Wikipedia.