Square Footage Calculators — Pick the Right Tool for Your Project
FootyCalc is a hub of free, specialised square footage tools. Use the quick calculator for rectangle rooms below, or jump to the scenario-specific calculator that fits your project — flooring, paint, tile, roofing, land, or whole-house.
Need every shape in one place? Open the full Square Footage Calculator for circles, triangles, trapezoids, L-shapes, and irregular rooms.
Last updated:Quick rectangle square footage calculator
Not a rectangle? Use the full seven-shape calculator for circles, triangles, trapezoids, L-shapes, irregular rooms, and multi-room totals.
One 12 × 10 room, five different quantities
Assume a measured interior rectangular floor of 12 ft × 10 ft, with four vertical walls of uniform 8-ft height. One 3-ft × 7-ft door opening and one 4-ft × 4-ft window opening are unpainted. No other deductions are modeled; ceiling and trim paint are excluded.
| What you need | Calculation | Result / next step |
|---|---|---|
| Measured floor area | 12 ft × 10 ft = 120 sq ft | 120 sq ft of physical floor. Do not deduct wall door or window openings from the floor area. |
| Flooring with an optional example 10% allowance | 120 sq ft × (1 + 10/100) = 132 sq ft | 132 sq ft of material before whole-carton rounding. The extra 12 sq ft is an allowance, not physical floor area. Check product and layout requirements in the flooring calculator. |
| Net wall area | Perimeter: 2 × (12 ft + 10 ft) = 44 ft Gross walls: 44 ft × 8 ft = 352 sq ft Openings: (3 ft × 7 ft) + (4 ft × 4 ft) = 37 sq ft Net walls: 352 sq ft − 37 sq ft = 315 sq ft | 315 sq ft of wall surface, not gallons. The paint measurement guide explains the next calculation: multiply by coat count and divide by product coverage. Its embedded tool is area-only. |
| Full-height room volume | 120 sq ft × 8 ft = 960 cu ft | 960 cu ft of geometric room volume, not a flooring quantity or an HVAC sizing recommendation. |
| Separate hypothetical 3-inch fill layer | Depth: 3 in ÷ 12 = 0.25 ft 120 sq ft × 0.25 ft = 30 cu ft 30 cu ft ÷ 27 = 1.111… cu yd | 30 cu ft ≈ 1.11 cu yd over the same footprint, before material-specific compaction, overage or supplier rounding. Use the area-and-depth calculator. |
The floor stays 120 sq ft in every row. The 10% flooring allowance is not automatically an allowance for paint or fill. The 3-inch layer is a separate example, not the room's 8-ft height.
To estimate paint, use net wall area × coats ÷ coverage in sq ft per gallon per coat. Coverage depends on the product and surface; check its instructions and round purchases to available container sizes. Sherwin-Williams' Painter Skills Program, pages 31–36, explains perimeter × wall height and separate wall, ceiling and trim calculations. Its 350-sq-ft-per-gallon example is not a universal coverage guarantee.
Interior floor area is not certified appraisal living area. Room totals alone do not establish which spaces qualify or compliance with the applicable measurement standard. For example, Fannie Mae's appraisal guidance, “Above- and Below-Grade Area(s)”, distinguishes those areas for its appraisal requirements; it is not a universal rule for every listing. Use the house calculator as an estimate and confirm measurement requirements for your intended use.
Choose a tool by what you know and what you need
Start with the wanted output, then check the missing inputs. A floor measurement alone cannot tell you paint gallons, fill volume or material length.
| Known input | Wanted output | Missing input | Existing tool |
|---|---|---|---|
| Floor length and width | Floor area in sq ft | Dimension units and confirmation that the floor is rectangular; other shapes need their own measurements. | Use the rectangle calculator above, or the full shape calculator. |
| Room length and width | Paint gallons for walls | Wall height, dimensions of unpainted openings, number of coats and product coverage per gallon per coat. Measure ceiling and trim separately if painting them. | Paint measurement guide; calculate gallons separately using the formula above and your product label. |
| Floor area | Fill volume in cu ft | Layer depth and its units; product-specific allowances and purchase rounding come afterward. | Sq ft to cubic feet calculator |
| An area value | The same area in different units | Source and target area units; no height or depth is needed. | Sq ft to square meters calculator, or square meters to sq ft |
| Area to cover | Material length in linear ft | Usable material width and its units; check layout and cuts separately. | Sq ft to linear feet calculator |
Specialized Square Footage Calculators
Choose a tool for the quantity you need. Project calculators offer different inputs and estimating assumptions; check waste, coverage and installation requirements for your actual product.
Main Calculator
All seven shapes with waste factor, cost, and visualization.
Room Calculator
Dedicated tool for bedrooms, kitchens, and living rooms.
House Calculator
Room-area totals and guidance on home-measurement scope.
Flooring Calculator
Hardwood, vinyl, and laminate with an example 10% allowance; check product and layout requirements.
Tile Calculator
Tile counts and box quantities with pattern waste.
Carpet Calculator
Convert floor area to square yards; check roll layout separately.
Paint Area & Gallon Guide
Measure wall area, then use coats and labeled paint coverage to estimate gallons separately.
Roof Calculator
Shingle squares and pitched-roof adjustments.
Cost per Sq Ft
Two-way converter for budgeting renovations.
Guides: Learn the Math Behind Square Footage
If you'd rather understand the formulas and measurement tricks than just click a tool, start with these plain-English guides.
How to Calculate Square Feet
Step-by-step guide for every shape, with worked examples.
Square Feet Formulas
Full formula reference for rectangles, circles, triangles, and L-shapes.
Inches & Feet to Sq Ft
Convert feet-and-inch tape readings to clean square footage.
Sq Ft vs Linear Feet
When to measure by area and when to measure by length.
Sq Ft vs Cubic Feet
Use area for flooring, volume for mulch, concrete, and HVAC.
Price per Square Foot
How real-estate, flooring, and renovation cost-per-sqft is calculated.
How Many Square Feet Is My Room?
Browse example room dimensions with unit conversions and related tools. These are reference sizes, not a survey of room-size popularity. For more context, see our room-size guide.
How many square feet is a 10x10 room?
100 sq ft — small bedroom, home office, flooring & paint estimates.
10×1210 × 12 = 120 sq ft
Standard bedroom.
12×12How much flooring for a 12x12 room?
144 sq ft — dining or guest room with waste & cost tables.
12×1512 × 15 = 180 sq ft
Small master bedroom.
14×1614 × 16 = 224 sq ft
Mid-size living room.
15×2015 × 20 = 300 sq ft
Large living room.
16×2016 × 20 = 320 sq ft
Large master suite.
20×2020 × 20 = 400 sq ft
Great room, two-car garage.
AllBrowse all sizes
See 60+ room dimensions with notes.
Project Questions
Each question links to a calculator or guide for that task.
- How many square feet is a 10x10 room?
- How to calculate square feet for flooring
- How much flooring do I need for a 12x12 room?
- Square feet to square yards for carpet
- Cost per square foot to build a house (2026)
- How many gallons of paint for a 10x10 room?
Unit Conversions at a Glance
The area conversions keep the same physical area. Using the exact international-foot definition, 1 ft = 0.3048 m, gives 1 sq ft = (0.3048)² sq m = 0.09290304 sq m exactly. See NIST Handbook 44 (2024), Appendix B, page B-8. Displayed calculator results may still be rounded.
The last two rows are not unit-only conversions: volume requires depth, and linear length requires material width. Both dimensions must be supplied in the units shown.
| From | To | Formula |
|---|---|---|
| sq ft | sq m | × 0.09290304 (exact factor; Sq Ft → Sq M) |
| sq ft | sq yd | ÷ 9 (Sq Ft → Sq Yd) |
| sq ft | acres | ÷ 43,560 (Sq Ft → Acres) |
| sq m | sq ft | ÷ 0.09290304 (exact factor; Sq M → Sq Ft) |
| acres | sq ft | × 43,560 (Acres → Sq Ft) |
| sq ft | sq in | × 144 (Sq Ft → Sq In) |
| sq ft + depth | cu ft | Area in sq ft × (depth in inches ÷ 12); requires depth (Sq Ft → Cu Ft) |
| sq ft + width | linear ft | Area in sq ft ÷ (width in inches ÷ 12); requires width (Sq Ft → Linear Ft) |
How to Check Your Estimate
- Check the shape. Length × width assumes a rectangle. Divide an irregular floor into non-overlapping shapes rather than using its longest dimensions as a bounding box.
- Keep area and order quantity separate. Total Area excludes waste. The optional material allowance and price use your selected waste percentage.
- Check the input units. Each dimension can use its own unit. Displayed results are rounded; measurement and shape assumptions still affect accuracy.
- Know the limits. These are estimating tools, not a survey, appraisal, building-code check, or product installation specification.
Frequently Asked Questions
How do I calculate square footage?
For a rectangle, multiply length by width in feet: 12 × 10 = 120 sq ft. For other shapes, open the full Square Footage Calculator; this homepage has a rectangle-only tool.
What is a square foot?
A square foot is the area of a square with 1-foot (12-inch) sides. One square foot equals 144 square inches, 0.09290304 square meters, or one ninth of a square yard.
Is this sqft calculator free?
Yes. The browser calculators are free and require no sign-up. Their calculations run locally in your browser; the separate developer API processes submitted requests on the server.
Which calculator should I use for my project?
Use this rectangle tool for floor area. For purchasing estimates, choose Flooring, Tile, Carpet, Paint, Roof, or Cost per Sq Ft from the directory above, then check that tool's assumptions against your project and product instructions.
How accurate is the result?
Results depend on your measurements, the chosen shape, unit conversion and display rounding. Decimal places are not an accuracy guarantee. Measure again if a small difference could change how much material you buy.
Does it work offline?
The calculator can keep working in an open tab after its scripts have loaded. Opening a saved HTML file alone or reloading without a connection is not guaranteed to work; the required JavaScript files must also be available.
Can I use inches, meters, or centimeters?
Yes. Each dimension has a unit selector: ft, in, yd, m, or cm. Inputs are converted to feet before the area is calculated, so you can mix units across fields.
What if my room has an alcove or cut-out?
Open the full calculator and split the occupied floor into non-overlapping rectangles using L-shape or Irregular mode. Do not include a missing corner or count an overlapping section twice.