Square Footage Calculator
Find the area of any room or space with this square footage calculator. Pick a shape, type the size, and read the area in square feet, square yards, square meters and square inches at once. Feet and inches sit in their own fields, so 12 ft 6 in never turns into the wrong 12.6 ft. The buy line then adds your waste percent, ready for a flooring, paint or yard order.
What the result numbers mean
The main answer. It is the true area of the shape you measured, in the unit that floors, paint and sod sell by.
The same area divided by 9. Carpet, sod and some fabrics price by the yard, so this line speaks their language.
The same area in metric. One set of measurements serves both unit worlds, with no second measuring round.
The area times 144. Small jobs like countertops and tile backsplashes read easier in inches.
Your area plus the waste percent. Order this amount and the cuts, the pattern and a damaged piece stay covered.
Odd rooms split into simple shapes. The L shape choice adds two rectangles for you, so no corner counts twice.
How do you calculate square footage?
Multiply the length by the width. A room that is 12 ft 6 in long and 10 ft 8 in wide is 12.5 ft by 10.67 ft. Its area is about 133 square feet. Convert inches to feet first, or the math goes wrong.
How the math works
Choose a rectangle, an L shape, a circle, a triangle or a trapezoid. Most rooms and yards match one of the five.
A room with a notch or a bay splits into two rectangles. The L shape choice runs both parts and adds them for you.
Inches turn into feet before any multiply. Six inches is half a foot, so 12 ft 6 in reads 12.5 ft, never 12.6 ft.
Inches / 12Each shape runs its own area rule. A rectangle multiplies length by width. A circle uses pi times the radius squared.
Length x WidthOne result shows square feet, square yards, square meters and square inches together. No second tool, no hand converting.
The buy line adds your waste percent. Ten percent covers straight cuts, 15 covers diagonal patterns, and complex rooms can need 20.
A living room, 12 ft 6 in by 10 ft 8 in
Here is the room from the quick answer, on a breakdown slip, the way the tool builds it.
Read the slip top to bottom. The convert lines come first, because inches typed as decimal feet are the top error on this topic. The wrong read of this same room, 12.6 by 10.8, gives 136 square feet and buys material the room never uses.
Each shape, explained
Every shape in this square footage calculator runs one clean area rule. Only the measuring changes. Find your shape below, measure the way it says, and tap a card to load that shape in the tool.
Rooms, floors, decks and most walls. Measure the full length and the full width. Feet and inches sit in their own fields, and the tool converts the inches for you.
Key measure: length and width, feet plus inchesTap to load in the calculatorRooms with a notch, a bay or a closet bump. Split the floor into two rectangles, measure each part, and the tool adds both parts into one total.
Key measure: two length and width pairsTap to load in the calculatorRound patios, pools, tree rings and fire pit pads. Measure straight across the middle. That line is the diameter, and the tool halves it into the radius.
Key measure: diameter across the middleTap to load in the calculatorCorner lots, angled garden beds and gable ends. Measure the base along the ground and the height straight up from the base, never along the slope.
Key measure: base and straight heightTap to load in the calculatorYards and driveways with two parallel sides of uneven length. Measure both parallel sides and the straight distance between them.
Key measure: side A, side B and heightTap to load in the calculatorFour more shapes, same habit
The tool runs rectangles, L shapes, circles, triangles and trapezoids. These four shapes show up in yards and patios too. Work the math here, then add your waste in the tool.
Slanted beds, angled patios and skewed lots. Multiply the base by the straight up height. The slanted side never enters the math.
Key measure: base times vertical heightA pie slice of a round bed or a curved patio corner. Take the slice angle over 360, times 3.1416, times the radius times itself.
Key measure: slice angle and radiusTree rings, fire pit surrounds and round paths. Run the full circle in the tool, run the inner hole as its own circle, and subtract the hole.
Key measure: outer area minus inner areaA border around a patio, a pool or a garden bed. Run the outer shape, run the inner shape, and subtract. The border is what stays.
Key measure: outer minus innerArea numbers, in one place
| Shape | Formula |
|---|---|
| Rectangle | Length times width |
| L shape | Section one area plus section two area |
| Circle | Pi times radius times radius |
| Triangle | Base times height, divided by 2 |
| Trapezoid | Side A plus side B, divided by 2, times height |
Common mistakes
12 ft 6 in is 12.5 ft, never 12.6 ft. This is the top error on this topic, and it grows with every inch on the tape.
A notched room forced into one rectangle counts a corner twice or drops it. Split the room and add the parts.
Small areas still drink material. Skip them in the measure and the flooring runs short on the last row.
Perimeter walks the edge of a room. Area covers the floor. A fence order needs the first, a floor order needs the second.
How to buy with your area number
The result moment is the buying moment. An area from this square footage calculator feeds two kinds of orders. Each route reads the number its own way.
Option A: Floor coverings
- Order the buy area, never the bare area. The waste percent covers cuts and pattern turns.
- Flooring sells by the box. Take the buy area to the flooring calculator and it counts the boxes.
- Carpet prices often read per square yard. The yard line in the result speaks that language.
- Keep the room sketch with the sizes on it. The store can check your split of an odd room in seconds.
Option B: Yard and bulk materials
- Yard materials need depth as well as area. The same area at 2 inches and at 4 inches doubles the order.
- The mulch, topsoil and gravel calculators take your area and a depth and return yards, tons and bags.
- Sod sells by the square foot or by the pallet. The bare area is the order number there, with a small waste margin.
- Past a few cubic yards, bulk delivery beats bags on price and on trips.
Measure a whole house room by room and add the rooms on this page. Then hand the area to the tool that owns the order. The flooring calculator counts boxes, and the mulch and topsoil calculators turn area plus depth into yards and bags.
Questions, answered
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