Flooring Calculator
A 20 by 15 foot room plus a 12 by 10 foot room is 420 square feet. Ten percent waste is 462 square feet, and 24 boxes at 20 square feet per box.
Last updated . Room sizes start in feet. Switch a room to yards or meters. Straight starts at 10 percent, diagonal at 15, and herringbone at 20. Box coverage starts at 20 ft², a planning figure. No price.
Enter up to three rooms. They are added, not overlapped. Waste follows the pattern. Boxes divide the area after waste by the square feet on the carton.
A tile size and a grout joint: tile calculator. Sand-and-cement screed: screed calculator. A bagged leveling compound: self-leveling concrete calculator.
Flooring for several rooms
The three rooms are added. They are not overlapped. Use 0 for a room you do not have.
10, 15, and 20 percent are planning allowances for straight, diagonal, and herringbone layouts. The box starts at 20 ft². Type the coverage on the carton. No price.
Results
How the floor area is counted
Net = room A + room B + room C. The rooms are added. They are not overlapped, and a wall they share is not subtracted. Leave a room at 0 when you do not have it. There is no separate square-footage page on this site. This is the multi-room floor.
Waste is a planning allowance by pattern: 10 percent straight, 15 percent diagonal, and 20 percent herringbone. The field stays editable until you change the pattern. Boxes = area after waste ÷ square feet per box, rounded up. The box starts at 20 ft² so the division can be checked. Type the coverage on the carton. This page does not count pieces from a tile size. That is the tile calculator. Why those percents are planning allowances, and what a large tile changes, is the tile waste guide.
Worked example
Leave every field as it opens: room A 20 ft by 15 ft, room B 12 ft by 10 ft, room C 0, pattern Straight, waste 10 percent, box coverage 20 ft². Room A reads 300.00 ft² · 27.87 m². Room B reads 120.00 ft² · 11.15 m². Room C reads 0.00 ft² · 0.00 m². Net reads 420.00 ft² · 39.02 m². With waste reads 462.00 ft² · 42.92 m². Boxes read 24. 462.00 ÷ 20 = 23.10, which rounds up to 24.
The same two rooms at the other patterns, then a third room of 10 by 8 feet at 10 percent.
| Pattern | Rooms | Net | With waste | Boxes |
|---|---|---|---|---|
| Straight, 10% | 20×15 and 12×10 | 420.00 ft² · 39.02 m² | 462.00 ft² · 42.92 m² | 24 |
| Diagonal, 15% | 20×15 and 12×10 | 420.00 ft² · 39.02 m² | 483.00 ft² · 44.87 m² | 25 |
| Herringbone, 20% | 20×15 and 12×10 | 420.00 ft² · 39.02 m² | 504.00 ft² · 46.82 m² | 26 |
| Straight, 10% | plus 10×8 | 500.00 ft² · 46.45 m² | 550.00 ft² · 51.10 m² | 28 |
Frequently asked questions
How much flooring for two rooms?
Leave room A at 20 ft by 15 ft, room B at 12 ft by 10 ft, and room C at 0. Room A reads 300.00 ft² · 27.87 m². Room B reads 120.00 ft² · 11.15 m². Room C reads 0.00 ft² · 0.00 m². Net reads 420.00 ft² · 39.02 m². At 10 percent, with waste reads 462.00 ft² · 42.92 m², and boxes read 24 at 20 ft² per box.
How is the net area added?
Net = room A + room B + room C. The rooms are added. They are not overlapped, and a shared wall is not subtracted. Use 0 for a room you do not have. There is no square-footage calculator on this site. This page is the multi-room floor.
How much extra for a diagonal layout?
Choose Diagonal, 15 percent. Net stays 420.00 ft² · 39.02 m². With waste reads 483.00 ft² · 44.87 m². Boxes read 25. Straight, diagonal, and herringbone set 10, 15, and 20 percent. Those are planning allowances. The waste field stays editable until the pattern changes.
How much extra for herringbone?
Choose Herringbone, 20 percent. With waste reads 504.00 ft² · 46.82 m². Boxes read 26. The net stays 420.00 ft² · 39.02 m². Twenty percent of 420.00 is 84.00, and 420.00 + 84.00 = 504.00.
What if there is a third room?
Set the pattern back to Straight so waste is 10, then set room C to 10 ft by 8 ft. Room C reads 80.00 ft² · 7.43 m². Net reads 500.00 ft² · 46.45 m². With waste reads 550.00 ft² · 51.10 m². Boxes read 28. 550.00 ÷ 20 = 27.50, which rounds up to 28.
How are the boxes counted?
Boxes divide the area after waste by the square feet per box and round up. The box starts at 20 ft², a planning coverage. Type the coverage on the carton. 462.00 ÷ 20 = 23.10, so the default order is 24 boxes. This page does not count tiles from a tile size. That count is the tile calculator.
Does this include grout, thinset, or screed?
No. This page is floor area, a pattern waste, and boxes. Grout in the joints is the grout calculator. Mortar under the tile is the thinset calculator. A sand-and-cement screed is the screed calculator. A bagged self-leveling compound is the self-leveling concrete calculator.