📐 Square Footage Calculator
Calculate the area of any room, lot, or project in square feet — plus square meters, square yards, acres, perimeter, and material cost. Rectangle, circle, triangle, and border shapes. Free, no sign-up.
A square footage calculator finds the area of a room, lot, or project — the space inside its boundary. It converts your dimensions into square feet, square meters, square yards, and acres, and also gives the perimeter and an estimated material cost. The standard area formula for a rectangle is:
How to calculate square footage in 3 steps:
- Pick a shape — rectangle, circle, triangle, or border — and measure its dimensions in feet.
- Enter the length and width (or diameter, or base and height). For irregular spaces, split into rectangles and total them.
- Click Calculate Area to see square feet, square meters, square yards, acres, perimeter, and material cost.
For example, a 12 ft × 10 ft room is 12 × 10 = 120 square feet. That equals about 11.15 square meters, 13.33 square yards, and 0.0028 acres, with a 44-foot perimeter for baseboards or trim.
Square Footage Calculator
Pick a shape, enter dimensions, see area in every unit plus perimeter and cost.
Measure Any Space Once –
and Know Exactly What It Will Take to Cover
Square footage is the number behind every flooring quote, paint estimate, and lot listing. Get it wrong and you over-buy materials or come up short mid-job. This free calculator turns your measurements into area in every unit — plus perimeter and material cost — in seconds.
⚡ Try the Calculator NowSquare Footage Is the Number Behind Every Project
Flooring, paint, sod, a property listing — each one starts with the same question: how many square feet? Area is the number every material order and cost estimate is built on. It is also the number that, measured a little carelessly, quietly costs you a box of tile or a gallon of paint.
A plain rectangle is just length times width — no trouble there. The trouble is that real rooms are not plain rectangles. They have alcoves, a bay window, a round patio off the back, a corner cut at an angle. The actual skill is not the multiplication. It is looking at an awkward space and seeing the two or three simple shapes hiding inside it, measuring those, and adding the pieces.
This Square Footage Calculator covers the four shapes that handle almost any real measurement — rectangle, circle, triangle, and border — and converts the result into square feet, square meters, square yards, and acres. It also returns the perimeter, useful for trim and edging, plus an optional material cost estimate.
How the Square Footage Calculator Works
Pick a shape, enter two or three measurements, and click once. The calculator returns the area in four units plus perimeter and cost. Here is what each field does.
Pick the Shape
Rectangle covers most rooms, lots, and panels. Circle handles round patios, pools, and tree rings. Triangle covers angled corners and gable walls. Border calculates the area of a frame or path around something — a walkway, a margin, a trim strip.
Enter the Dimensions
For a rectangle, enter length and width. For a circle, the diameter — the full distance across the widest point. For a triangle, the base and the perpendicular height. For a border, the outer length and width plus the border strip width.
📐 Decimal feet work fine — enter 12.5 for 12 feet 6 inches.Switch Units If Needed
The Imperial / Metric toggle lets you enter measurements in feet or meters. The result still shows every unit — square feet, square meters, square yards, and acres — so you can read whichever your plans, supplier, or listing uses.
Enter the Number of Areas
If you are measuring several identical spaces — four matching rooms, three identical panels, a row of planter beds — enter the count and the calculator totals them in one step. For a single space, leave this at 1.
Set Waste Factor & Project Type
In Advanced mode, choose a waste factor for material cuts and a project type that auto-fills a price per square foot. This turns the raw area into a realistic order quantity and a material cost estimate.
Hit Calculate — Read Every Number
Instantly see total square feet, square meters, square yards, acres, perimeter, the area to order with waste, and the estimated material cost.
✅ Rectangle formula: Area = Length × WidthThe Formula Behind Each Shape
Every shape in this calculator uses an exact geometric formula — no estimates, no averages. Here is the math, in plain language, for each one.
Rectangle: Area equals length multiplied by width. A 12-foot by 10-foot room is 120 square feet. A square is just a rectangle where both sides are equal. This is the formula behind the large majority of real measurements.
Circle: Area equals π (about 3.14159) multiplied by the radius squared. The radius is half the diameter. For a round patio measured at 16 feet across, the radius is 8 feet, so the area is 3.14159 × 8 × 8 ≈ 201 square feet. Always measure the diameter through the true center.
Triangle: Area equals one-half the base multiplied by the height. The height must be the perpendicular distance from the base to the opposite point, not the slanted side. A triangle with a 12-foot base and an 8-foot perpendicular height is 0.5 × 12 × 8 = 48 square feet. The area formula holds for any triangle; this calculator's perimeter reading assumes a right angle between the base and height.
Border: Area equals the outer rectangle minus the inner rectangle. Enter the outer length and width and the width of the border strip; the calculator subtracts the inner space the border surrounds. A 26 by 22 outer area with a 3-foot border has a 20 by 16 inner area, leaving 572 − 320 = 252 square feet of border. This is how you measure a walkway, a margin, or a frame.
Area Unit Conversions Every Measurer Should Know
Square footage rarely travels alone. Carpet is quoted by the square yard, plans may be in square meters, and land is in acres. These are the conversions that link them all.
| Conversion | Multiplier | When You Use It |
|---|---|---|
| Square feet → square yards | ÷ 9 | Comparing carpet quotes, which are priced per square yard |
| Square feet → square meters | × 0.0929 | Working with metric plans or international suppliers |
| Square feet → acres | ÷ 43,560 | Measuring lots, land, and large parcels |
| Square meters → square feet | × 10.764 | Converting metric measurements back to US units |
| Square yards → square feet | × 9 | Turning a carpet quote into a per-square-foot comparison |
| Acres → square feet | × 43,560 | Breaking a land parcel into a usable area figure |
The conversions in plain language: A square yard is a 3-foot by 3-foot square, so it holds 9 square feet. A square meter is slightly larger than a square yard — about 10.76 square feet. An acre is 43,560 square feet, roughly the playing area of a US football field minus the end zones. Memorising the "÷ 9" and "× 0.0929" pair covers most everyday flooring and plan work.
Quick Reference: Common Room Sizes
| Room | Typical Dimensions | Square Footage |
|---|---|---|
| 🛏️ Small bedroom | 10 × 10 ft | 100 ft² |
| 🛏️ Average bedroom | 12 × 12 ft | 144 ft² |
| 🛋️ Living room | 15 × 18 ft | 270 ft² |
| 🍳 Kitchen | 12 × 14 ft | 168 ft² |
| 🚗 Two-car garage | 22 × 22 ft | 484 ft² |
| 🏡 Small lot | 50 × 100 ft | 5,000 ft² (0.11 acre) |
Factors That Affect Your Square Footage Measurement
The formula is exact, but the inputs are where accuracy is won or lost. Here are the variables that change your result — and which way they push it.
Measuring by Shape: Which Formula Fits Your Space
Most measuring problems come down to recognising which shape — or combination of shapes — describes the space in front of you. Here is how the four compare.
| Shape | What You Measure | Use It For | Watch Out For |
|---|---|---|---|
| Rectangle | Length and width | Standard rooms, lots, walls, panels | Out-of-square walls — measure both sides |
| Circle | Diameter across the center | Round patios, above-ground pools, tree rings | Measuring a chord instead of the true diameter |
| Triangle | Base and perpendicular height | Angled corners, gable-end walls, pie-shaped lots | Using the slanted side instead of the height |
| Border | Outer dimensions and strip width | Walkways, garden edging, painted margins, frames | Confusing inner and outer dimensions |
| Combination | Each piece separately | L-shaped and irregular rooms | Overlapping or leaving gaps between pieces |
How to Measure a Space, Step by Step
A reliable measurement follows the same four phases every time, whether it is a single bedroom or a whole house.
Make a rough sketch of the room or lot — it does not need to be to scale. Mark every wall, closet, alcove, and angled section. The sketch becomes the place you record each measurement, and it forces you to notice the irregular parts before you start.
On your sketch, draw lines that break the space into rectangles, triangles, and circles. Aim for the fewest pieces that cover everything without overlapping. Most rooms split into two or three rectangles at the inside corners.
Measure each piece at floor level with a taut tape or laser. For rooms that may be out of square, measure both lengths and both widths. Write every number directly on the sketch next to the wall it belongs to, in feet with one decimal.
Enter each shape into the calculator, note its square footage, and add the pieces for the grand total. Then apply a waste factor for material ordering. Keep the sketch with the numbers on it — it is your reference if a supplier or contractor questions the figure.
What Square Footage Costs to Cover in 2026
Once you know the area, the next question is always cost. Most coverings are priced per square foot, so your area number multiplies straight into a budget.
The calculator's Advanced mode includes a project type that auto-fills a typical 2026 material price per square foot. Multiply that by the area-with-waste and you have a material estimate. Installation is usually a separate charge, often in the same range as the material itself.
| Space | Area | Laminate Material | Tile Material |
|---|---|---|---|
| Small bedroom | 100 ft² | $220–$330 | $440–$770 |
| Living room | 270 ft² | $590–$890 | $1,190–$2,080 |
| Kitchen | 168 ft² | $370–$550 | $740–$1,290 |
| Two-car garage | 484 ft² | $1,060–$1,600 | $2,130–$3,730 |
| Whole 1,500 ft² home | 1,500 ft² | $3,300–$4,950 | $6,600–$11,550 |
Example Square Footage Calculations
Three spaces, three shapes — each worked through with verified math so you can sanity-check your own results.
Getting an Accurate Square Footage Every Time
Accuracy comes from method, not from math. These habits separate a measurement you can order materials against from a guess that leaves you short or over-bought.
The biggest single improvement is splitting irregular spaces into simple shapes. People lose accuracy when they try to force an L-shaped room into one rectangle, eyeball an "average" width, or skip the alcove entirely. A space drawn as two clean rectangles is two exact calculations; the same space guessed as one is one inexact one.
The second habit is measuring both directions of a room. Houses settle and walls bow, so the two lengths of a "rectangular" room often differ by several inches. Measuring both and averaging — or splitting the room — captures area that a single reading misses.
Six Habits for a Reliable Measurement
When This Calculator Is the Wrong Tool
The four shapes cover the large majority of measuring jobs, but not every one. Here are the situations where you need something more.
1. Truly free-form curves. A kidney-shaped pool or a curving garden bed is not a circle or a rectangle. Approximate it by splitting it into shapes you can measure, or for a precise figure use a planimeter, a measuring wheel along a grid, or a mapping app that traces the outline.
2. Non-right triangles where you need the perimeter. The triangle area formula (½ × base × height) is exact for any triangle. But this calculator's perimeter reading assumes a right angle between the base and height. For a triangle with three known but unequal sides, the area is best found with Heron's formula and the perimeter by adding the three measured sides directly.
3. Official home appraisals and listings. Real estate square footage follows specific regional standards — which spaces count, how walls are measured, what ceiling height qualifies. This calculator gives you usable floor area; it does not replace a professional appraisal or an ANSI-standard measurement for a property listing.
4. Sloped and three-dimensional surfaces. A pitched roof, a ramp, or a hillside has more surface area than its flat footprint. For those, the flat measurement understates the real coverage area. A roofing or slope calculator that accounts for pitch is the right tool.
Where to go instead: Once you have the area, pair this with a material calculator for what you are installing — flooring, paint, sod, or gravel. For volume jobs that need a depth as well — concrete, mulch, soil — use a calculator that multiplies area by depth. This tool's job is the flat area, which is the starting point for all of them.
Square Footage Terms You'll See On This Page
Quick reference for the area and measurement terms used throughout this calculator.
- Square Foot (ft²)
- The area of a square one foot on each side. The standard US unit for room, building, and flooring area.
- Square Yard (yd²)
- The area of a square one yard (3 feet) on each side, equal to 9 square feet. Carpet is commonly priced per square yard.
- Square Meter (m²)
- The metric area unit — a square one meter on each side, equal to about 10.764 square feet. Standard outside the US.
- Acre
- A land-area unit equal to 43,560 square feet, or about 0.405 hectares. Used for lots and parcels rather than buildings.
- Area
- The amount of two-dimensional space inside a boundary. What you measure to buy flooring, paint, sod, or tile.
- Perimeter
- The total distance around the edge of a shape. Used for baseboard, trim, fencing, and edging — a different measurement from area.
- Diameter
- The distance straight across a circle through its center. The radius is half the diameter.
- Radius
- The distance from the center of a circle to its edge — half the diameter. The circle area formula uses the radius squared.
- Base & Height (Triangle)
- The base is one side of a triangle; the height is the perpendicular distance from that base to the opposite point. Area is half their product.
- Border Area
- The area of a frame or strip around a shape, found by subtracting the inner area from the outer area.
- Waste Factor
- A percentage added to measured area to cover cuts, trim, and spare material. Typically 5–10%, more for diagonal or patterned layouts.
- Footprint
- The flat ground area a structure or shape occupies, viewed from directly above — before any slope or vertical surface is considered.
- Out of Square
- A room whose corners are not true 90-degree angles or whose opposite walls differ in length. Common in older buildings.
- Gross vs Usable Area
- Gross area includes wall thickness and structure; usable (or net) area is the open floor space inside the walls.
Frequently Asked Questions
The most common questions about calculating and measuring square footage — answered clearly.
How do I calculate square footage?
Multiply length by width for a rectangular area, with both measurements in feet. A room 12 feet by 10 feet is 12 × 10 = 120 square feet. For other shapes: a circle is π × radius squared; a triangle is half the base times the height. If a room has an irregular shape, split it into rectangles, calculate each one, and add the results. This calculator does all four shapes and the unit conversions automatically.
How many square feet are in a square yard?
One square yard equals 9 square feet, because a yard is 3 feet and 3 × 3 = 9. To convert square feet to square yards, divide by 9. To convert square yards to square feet, multiply by 9. Carpet is often priced by the square yard, so this conversion matters when comparing carpet quotes against flooring priced per square foot.
How do I convert square feet to square meters?
Multiply square feet by 0.0929 to get square meters. To go the other way, multiply square meters by 10.764 to get square feet. For example, a 200 square foot room is 200 × 0.0929 = 18.58 square meters. This calculator shows both units at once, so you can read whichever your supplier or plans use.
How many square feet are in an acre?
One acre is 43,560 square feet. To convert square feet to acres, divide by 43,560; to convert acres to square feet, multiply by 43,560. An acre is roughly the size of a US football field without the end zones. For lot and land measurements, acres are the standard unit; for rooms and buildings, square feet are used.
How do I measure the square footage of a room?
Measure the length and the width of the room in feet using a tape measure, then multiply them. For an L-shaped or irregular room, divide it into separate rectangles, measure and multiply each one, and add the totals. Measure at floor level, include closets if they will be floored, and round each measurement to the nearest few inches — small measurement errors have little effect on the total.
How do I calculate the square footage of a circle?
The area of a circle is π (about 3.14159) multiplied by the radius squared. The radius is half the diameter. For a round patio 16 feet across, the radius is 8 feet, so the area is 3.14159 × 8 × 8 = about 201 square feet. Select the Circle shape in this calculator and enter the diameter — the full width across the center — and it does the rest.
What waste factor should I use for flooring?
A 5–10% waste factor is standard for flooring. Use 5% for a simple rectangular room with straight runs; 10% (the recommended default) for most rooms; and 15–20% for diagonal or herringbone layouts, rooms with many corners, or patterned material that needs matching. The waste covers cuts, trim pieces, and a few spare planks or tiles for future repairs.
How do I calculate square footage for an irregular room?
Break the irregular space into simple shapes — rectangles, triangles, and circles — that together cover the whole area without overlapping. Calculate the square footage of each piece separately, then add them together. Most L-shaped, T-shaped, and alcoved rooms split cleanly into two or three rectangles at the inside corners. This calculator's Number of Areas field can total identical pieces in one step.
What is the difference between square footage and perimeter?
Square footage measures area — the space inside a boundary, used for flooring, paint, and sod. Perimeter measures the distance around the edge, used for baseboards, trim, fencing, and edging. They are different measurements: a long narrow room and a square room can have the same square footage but very different perimeters. This calculator shows both.
How much does flooring cost per square foot in 2026?
In 2026, flooring material runs roughly $1–$8 per square foot in the US: laminate and basic carpet around $2–$3, vinyl plank around $3–$5, tile around $4–$7, and hardwood around $6–$10. Installation typically adds $2–$6 per square foot. This calculator's material estimate uses the type you select; always get local quotes for an accurate total.
How do I find the square footage of a house?
Add the floor area of every finished, heated room measured from inside the walls, including hallways and stairwells. Standard practice excludes unfinished basements, attics, garages, and open porches. Measure each room's length by width, sum the rooms, and the total is the home's finished square footage. Listed home sizes follow this convention, though local appraisal rules vary.
Does square footage include walls and closets?
For flooring and finishes, you measure the usable floor area inside the walls, and closets are included if they will be floored. For a home's listed living area, square footage is measured to the inside face of exterior walls, so interior wall thickness is included but the wall cavities are not separated out. Always confirm which standard your project or listing uses.
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