Square Footage Calculator
Pick a shape, enter the measurements, and get the exact area — plus how much material to order with waste included.
An L-shape is two rectangles added together. Measure each section separately.
Extra material for cuts and mistakes — 10% is the standard for flooring and tile.
Measure each wall twice and round up — it is cheaper than running short mid-project.
Square Footage Calculator
Four shapes, four units, one honest number — plus exactly how much material to order so you never drive back to the store mid-project.
The Saturday That Taught Me to Measure Twice
A few years ago I helped a friend lay laminate in a 12-by-10-foot bedroom. We did the math on a scrap of cardboard: 12 × 10 = 120 square feet, so we bought exactly 120 square feet of flooring. Confident. Efficient. Wrong.
By late afternoon we were staring at a half-finished floor and a pile of offcuts too small to use anywhere. Cuts around the doorway, the closet corner, two boards ruined by a slipped saw — it all added up to about twelve missing square feet. One more trip to the store, one more hour gone, and the new boxes were from a different dye lot, a shade off from the morning's work.
That day is why a good square foot calculator does two things, not one: it gives you the exact area and it adds the waste allowance before you order. The calculator on this page does both — pick a shape, type your measurements, and it hands you the total plus the "order this much" number with waste already folded in.
Four Projects, Four Shapes
The fastest way to understand square footage is to walk through real rooms. Each project below uses one shape, shows the formula, and ends with the number you'd actually order. Every result matches what the sqft calculator on this page produces — try them yourself.
The bedroom floor
The room is 12 ft long and 10 ft wide. A rectangle's area is simply length times width:
Now the part most people skip: waste. Flooring gets cut around doorways and closets, and miscuts happen. The standard allowance is 10%:
Practical finish: if each laminate box covers 20 sq ft, that's 132 ÷ 20 = 6.6 boxes — so you buy 7 boxes. Always round up; an unopened box can go back, a half-finished floor cannot.
The L-shaped living room
Odd-shaped rooms scare people, but the trick is boring: split the L into two rectangles, measure each, and add them. Our living room splits into Section A (12 × 8 ft) and Section B (6 × 4 ft):
With 10% waste that's 132 sq ft to order — same as the bedroom, interestingly, even though the rooms look nothing alike. That's the thing about area: shape doesn't matter, only the total.
The round patio
For a circular patio you only need one measurement: the radius (center to edge). Ours is 5 ft. The formula is π times radius squared:
Only have a tape long enough to measure straight across? That's the diameter — 10 ft here — and the calculator accepts that too, halving it for you: same 78.54 sq ft. If you're laying 12-inch square pavers (1 sq ft each), that's 79 pavers plus 10% waste, so grab 87.
The triangular flower bed
Wedge-shaped beds and gable ends are triangles: half of base times height. Base 8 ft, height 6 ft (measured straight up from the base at a right angle, not along the slope):
Ordering sod or mulch? 24 sq ft plus 10% waste = 26.4 sq ft. For mulch depth, remember that area is only half the story — but for coverage, this number is the whole story.
Every Formula on One Card
Bookmark this table. It covers every shape the calculator handles — and every shape you'll meet in a house:
| Shape | What to measure | Formula |
|---|---|---|
| Rectangle | Length and width | L × W |
| Square | One side | S × S (a rectangle where L = W) |
| L-shape | Both rectangles' sides | (A₁ × B₁) + (A₂ × B₂) |
| Circle | Radius or diameter | π × r² |
| Triangle | Base and vertical height | ½ × base × height |
A room that's a rectangle with a rectangular closet jutting in? That's an L-shape in disguise — split and add. A bay window bump-out? A rectangle plus a triangle. Nearly every "weird" room is just two or three simple shapes wearing a trench coat.
When One Shape Isn't Enough
Real rooms rarely match a single diagram. The bay window jutting out of the bedroom, the fireplace bump in the living room wall — the method never changes: break the room into simple shapes, measure each, and add them up.
Take the bedroom from Project 1 (120 sq ft) with a triangular bay window added. The window's base is 6 ft along the wall, and it sticks out 3 ft — measured straight out from the wall, not along the angled glass:
With 10% waste that's 141.9, so you order 142 sq ft. The calculator handles one shape per run, so do two quick runs and add the totals — thirty seconds of work, and your number survives contact with reality.
How to Use the Square Footage Calculator
Here's exactly what happens when you run the tool at the top of this page — no surprises, no hidden steps:
- Pick a shape. Four buttons: Rectangle, L-Shape, Circle, Triangle. The input panel switches instantly to show only the fields that shape needs.
- Pick your unit. The ft / in / m / cm toggle converts everything behind the scenes, so you can measure with whatever tape you own.
- Circle only: radius or diameter? A second toggle lets you enter whichever one you actually measured — the calculator halves the diameter for you.
- Type your measurements. Plain number fields. Pressing Enter in any field calculates too, if you like keyboard speed.
- Set the waste allowance. It starts at the standard 10%. Drag it to 0–100 depending on the job (more on that below).
- Hit Calculate. You get the big total in square feet, the exact formula it used (so you can double-check the math), a green "Order X sq ft" chip with waste included, and instant conversions to square inches, square yards and square meters.
- Reset clears every field and returns waste to 10% for the next room.
Measure in Whatever Unit You Have
Not everyone owns a tape marked in feet. Maybe your laser measure reads meters, or you're working from a plan dimensioned in inches. A proper sq ft calculator shouldn't make you convert by hand — and this one doesn't. It converts every entry to feet internally (1 inch = 1/12 ft, 1 meter = 3.28084 ft) before doing the area math.
Example: a room measured as 10 m × 4 m becomes 430.56 sq ft automatically. Try switching the unit toggle mid-calculation and watch the same room give the same answer.
What the three conversions are for
| Conversion | Math | When you need it |
|---|---|---|
| Square inches | × 144 | Small tiles and cut lists — 120 sq ft = 17,280 sq in |
| Square yards | ÷ 9 | Carpet is priced per square yard — 120 sq ft = 13.33 sq yd |
| Square meters | × 0.092903 | Tiles and flooring sold metric — 120 sq ft = 11.15 sq m |
The Waste Allowance, Demystified
Waste is the material that ends up as offcuts, broken pieces and miscuts. The calculator's order chip uses one simple formula:
So which percentage do you pick?
| Waste | Use it when… |
|---|---|
| 5% | Simple rectangle, large tiles or planks, and you've done this before. |
| 10% | The default. Standard flooring, tile and sod jobs with a few corners or doorways. |
| 15% | Diagonal tile layouts, rooms with many angles, or your first DIY attempt. |
Why not just buy exactly the area? Because flooring and tile are cut from fixed-size pieces — a 4-inch strip cut off a 12-inch plank to fit a wall leaves an 8-inch offcut that rarely fits anywhere else. Those slivers are the waste, and every room has them. Ordering short means a second trip, a possible dye-lot mismatch, and a stalled project. Ordering 10% over means, at worst, returning one unopened box.
What You'll Actually Buy With the Number
Square footage is never the end of the story — it's the key that unlocks the shopping list:
- Flooring: boxes are labeled with their coverage in sq ft. Divide your order total by the box coverage and round up — 132 sq ft ÷ 20 = 7 boxes.
- Paint: one gallon covers roughly 350 sq ft. Walls of a 12 × 10 ft room with 8 ft ceilings: 2 × (12 + 10) × 8 = 352 sq ft — one gallon, with a splash to spare.
- Carpet: priced per square yard, so convert first: 120 sq ft ÷ 9 = 13.33 sq yd. Order 15 to be safe.
- Tiles: boxes state their coverage in sq ft — a 48 sq ft bathroom needs 48 × 1.10 = 52.8 sq ft, so 6 boxes at 10 sq ft each.
- Pavers and 12-inch tiles: each piece is near enough 1 sq ft — your square footage is your piece count before waste.
- Sod and mulch: sold by the sq ft (sod rolls) or cubic yard (mulch) — area gets you to the register either way.
Four Measuring Mistakes That Cost Real Money
After watching friends — and myself — get this wrong, these are the four errors that actually cost cash:
1. Measuring the wall instead of the floor
Baseboards steal roughly half an inch per wall. Across a whole room that quietly adds up to square feet you don't have. Measure wall-to-wall at floor level, or better yet, measure the open floor itself where the material will actually lie.
2. Mixing feet and inches in one number
"10 feet 6 inches" typed as 106 is a disaster — the calculator reads it as one hundred and six feet. Convert first: 10.5 ft. The unit toggle converts between whole unit systems, but a feet-and-inches combo must be decimalized by you before typing.
3. Measuring the slope instead of the height
For triangles, height means the vertical drop from the base to the tip — not the slanted edge you can comfortably reach with a tape. Measure the slope and you'll overstate the area every single time, then wonder why you have half a box left over.
4. Measuring once, on a bad day
Tapes kink, the hook slips off the wall, and tired eyes read 63 as 68. Measure twice. If the two readings disagree, take a third — the odd one out is the liar. Two extra minutes now beats a second trip to the store later, every time.
Questions People Ask
Measure the length and width in feet, then multiply them. A 12 ft by 10 ft room is 12 × 10 = 120 sq ft. For L-shaped rooms, split the shape into two rectangles, calculate each, and add the results. The calculator above does all of this — including the waste allowance — in one click.
Yes — "square foot calculator," "sqft calculator" and "sq ft calculator" are three names for the same tool. "Sqft" and "sq ft" are just abbreviations of "square feet." They all compute area the same way.
Divide the L into two rectangles on paper. Measure each rectangle's length and width, multiply to get each area, then add them together. For example, (12 × 8) + (6 × 4) = 96 + 24 = 120 sq ft. Choose "L-Shape" in the calculator and it walks you through exactly this.
10% is the industry standard for flooring, tile and sod — it covers cuts, offcuts and the occasional miscut. Use 5% for simple rectangles with large pieces, and 15% for diagonal layouts or rooms with lots of corners. The calculator applies whatever percentage you set and shows the final order quantity.
Divide by 9 for square yards (120 sq ft = 13.33 sq yd) and multiply by 0.092903 for square meters (120 sq ft = 11.15 sq m). The calculator shows all three conversions automatically under every result.
Yes. Switch the unit toggle to in, m or cm and type your measurements as-is — the calculator converts them to feet before calculating, so the square footage comes out correct without any manual conversion.
The Two-Minute Tape Checklist
Run through this before you order anything, and you'll never repeat the Saturday-afternoon flooring disaster:
- Measure every wall twice — tapes slip and eyes misread.
- Measure in feet, or let the calculator convert your inches or meters.
- Sketch L-shapes as two labeled rectangles before touching the math.
- Add the 10% waste allowance before you fall in love with the base number.
- Round up to whole boxes, gallons or rolls — never down.
- Keep one spare box; dye lots change and floors get damaged.
That's the whole craft. Measure honestly, add your waste, order once — and spend Saturday installing instead of driving back to the store.