Choose the shape
Use Rectangle for most rooms and floors. Choose Square, Circle, Triangle, or Trapezoid when the outline calls for it.
ROOM • FLOOR • LOT
Square Footage Calculator for Rooms, Floors, and Lots
Use this square footage calculator to measure rooms, floors, walls, yards, lots, and other surfaces. Enter feet, inches, yards, meters, or centimeters, then see square feet with optional waste and cost estimates.
Jump to the calculator
No account or upload required
- US customary and metric units
- Multiple areas for irregular spaces
- Feet-and-inches input support
- Waste and material cost estimates
MEASURE YOUR SPACE
Calculate square footage
Use the square footage calculator for one simple area: choose a shape, enter dimensions, and add areas when a floor plan is irregular.
01
CALCULATOR INPUTS
Enter dimensions
02
CALCULATED RESULT
Your area estimate
Example result
192
sq ft
A 12 ft × 16 ft rectangle gives 192 square feet.
- Base area
- 192 sq ft
- Square meters
- 17.84 m²
- Square yards
- 21.33 sq yd
- Square inches
- 27,648 sq in
Material area
211.20 sq ft
Estimated cost
$739.20
Area breakdown
1 area
- Area 112 ft × 16 ft = 192 sq ft
Formula used
12 ft × 16 ft = 192 sq ft
Example includes 10% waste and $3.50 per sq ft. Adjust both values.
Enter valid dimensions to see the result
Check the highlighted fields and calculate again. Results include conversions, coverage, and cost when available.
Calculations run in your browser; measurements are not uploaded.
Rectangle: length × width = square feet. Choose another shape or add separate areas when needed.
A SIMPLE WORKFLOW
How to use the square footage calculator
Measure each area, choose its shape, and let this square footage calculator convert units before applying the formula.
Enter the dimensions
Enter each side and its unit. Feet, inches, yards, meters, centimeters, and ft + in are supported.
Add areas when needed
Split an L-shaped or multi-room plan into non-overlapping sections, then add another area.
Review the estimate
Review square feet and conversions. Add waste and price when you need a material estimate.
THE MATH BEHIND THE RESULT
How to calculate square footage
Measure length and width, convert them to one unit, and multiply. Results are reported in square feet while the original units remain visible.
Square footage calculator formula
square feet = length in feet × width in feet
For inches, divide by 12 before multiplying. One square meter is about 10.7639 square feet.
Rectangle
length × width
Square
side × side
Circle
π × radius²
Triangle
base × height ÷ 2
Trapezoid
(base 1 + base 2) × height ÷ 2
A 12 ft × 16 ft room
Confirm both sides use the same unit, then multiply for geometric area before waste.
12 ft
16 ft
= 192 sq ft
With 10% waste, the planning area is 211.20 sq ft; use it as an allowance, not an order guarantee.
ROOM MEASUREMENT
Calculate the square footage of a room
Preserve real measurements instead of rounding every wall. Measure the usable section and separate attached spaces that change the outline.
Measure wall to wall
Measure the longest wall and adjacent wall from consistent points. Keep inches instead of rounding 11 ft 8 in to 12 ft.
Split irregular spaces
Split alcoves, closets, entries, or bump-outs into separate rectangles so the total is easy to check.
Use quantity for repeats
Use Quantity for repeated rooms; add separate areas when dimensions differ.
Separate floor from wall area
Floor and wall area are different. Measure each surface and account for doors, windows, trim, and product coverage.
FEET + INCHES TIP
Keep the fractions from your tape measure
Choose ft + in for whole feet plus leftover inches. The calculator converts 11 ft and 8 in to 11.6667 ft instead of rounding to 12 ft.
PROJECT PLANNING
Square footage for flooring and material cost
A square footage estimate is often the first project number. Add waste and price per square foot to see planning coverage and cost.
Flooring and carpet
Add allowance for seams, offcuts, damaged boards, patterns, and room shape. Follow the manufacturer’s coverage guidance.
Tile and hard surfaces
Diagonal layouts, corners, and matching can increase tile needs. Review adjusted coverage beside the base area.
Paint, wall, and garden work
Measure each wall or garden section separately. For paint, use product coverage and account for coats.
How the estimate is calculated
Material area = base area × (1 + waste ÷ 100). Estimated cost = material area × price per sq ft.
COMMON FORMULAS
Square footage formulas for common shapes
Use simple non-overlapping shapes for complex plans, then add their areas.
| Shape | Formula | Useful for |
|---|---|---|
| Rectangle | length × width |
Rooms, floors, walls, patios, lots |
| Square | side × side |
Equal-sided rooms or pads |
| Circle | π × radius² |
Round beds, pools, rugs, zones |
| Triangle | base × height ÷ 2 |
Gables, corners, triangular sections |
| Trapezoid | (base 1 + base 2) × height ÷ 2 |
Tapered sections |
| Multiple areas | area 1 + area 2 + area 3 |
L-shaped or irregular plans |
CHECK THE ASSUMPTIONS
Square footage calculator accuracy and limits
Use this tool for quick geometric planning, not official property measurements, professional takeoffs, or guaranteed material orders.
Measure twice before ordering
Recheck corners, openings, wall lengths, and units before buying. Keep exact measurements and use waste as an allowance.
Know when surface area changes
A horizontal footprint may differ from a sloped roof, stairs, curved wall, vaulted ceiling, or uneven site. Measure unusual surfaces separately.
Do not use it for official records
Official living area, appraisal, tax, permit, and legal measurements can follow local rules for walls, garages, stairs, balconies, and unfinished space.
The basic calculation stays local
Calculations run locally in your browser without an account or upload. Optional third-party services have their own privacy practices.
METHOD NOTE
Consistent units make a trustworthy result
Dimensions are converted to feet before the shape formula runs. Results are rounded for display; compare estimates using the same boundaries, units, and space definition.
COMMON QUESTIONS
Square footage calculator FAQ
Get quick answers about this square footage calculator, formulas, units, rooms, waste, and material estimates.
What is the formula for square footage?
For a rectangle, convert length and width to the same unit, then multiply. For other shapes, use the matching formula and add separate non-overlapping areas.
How do I calculate square feet of a room?
Measure length and width, keep units consistent, and multiply. For an irregular room, split the outline into simple shapes and add each result.
Can I use feet and inches in the calculator?
Yes. Choose ft + in, enter whole feet and leftover inches, and let the calculator convert the pair before applying the formula.
How many square feet are in a square meter?
One square meter is approximately 10.7639 square feet. The result panel also shows square yards and square inches for a quick check.
Should I add a waste factor for flooring or tile?
Often. Cuts, seams, damage, patterns, and installation mistakes can require extra material. Choose a reasonable allowance and follow product guidance.
How do I find the square footage of an L-shaped room?
Divide the L shape into non-overlapping rectangles. Add each with Add another room or area, then review the breakdown instead of measuring one large rectangle around empty space.
Does the calculator find the official square footage of a house?
No. It calculates the geometric area represented by your dimensions. Official finished living area can follow local rules for walls, ceilings, garages, stairs, balconies, and unfinished spaces.
Can I calculate material cost with this tool?
Yes. Enter waste and a price per square foot to see base area, adjusted coverage, and estimated cost. Labor, delivery, tax, fees, and product coverage are not included.
READY TO MEASURE?
Start your square footage estimate
Enter the measurements you have and keep the formula, conversions, waste allowance, and breakdown together for an easier estimate.