Free 23 calculators · 25 guides · no sign-up
Measure rooms.
Plan materials.
Buy with confidence.
Free calculators for the interior projects that are easiest to get wrong at the hardware store. See the math, adjust the assumptions, and leave with a practical quantity.
A simple footprint to keep your measurements grounded.
Start with the room
Enter the floor dimensions in feet. You can switch units once you open the full calculator.
Your measurements stay in your browser.
Browse by project.
Every project type has its own hub, workflow, and guides.
Popular calculators.
Pick a tool, enter the measurements you have, and refine from there.
Square Footage Calculator
Find floor area, square yards, and room perimeter from length and width.
MeasurementWall Area Calculator
Calculate gross and net wall square footage after doors and windows.
MeasurementPaint Calculator
Estimate gallons of wall paint from room size, coats, coverage, and allowance.
PaintFlooring Calculator
Convert room area into flooring boxes with a visible waste allowance.
FlooringFlooring Cost Calculator
Budget flooring material, optional installation, and underlayment.
FlooringCarpet Calculator
Plan roll-width runs, seams, and square yards of carpet for a room.
FlooringTile Calculator
Count tiles from area, tile size in inches, and a transparent allowance.
TileDrywall Calculator
Count 4 × 8 or 4 × 12 drywall sheets from net wall area.
Walls & TrimWallpaper Calculator
Estimate rolls from full-height drops, pattern repeat, and trim.
Walls & TrimRug Size Calculator
Find the largest standard area rug that leaves a balanced floor border.
Room PlanningCurtain Size Calculator
Size the rod, curtain length, and number of panels for the fullness you want.
Room PlanningTV Viewing Distance Calculator
Find the seating distance range for a TV size, or the TV size for your couch.
Room PlanningHow a project comes together
A room project is a chain of small decisions.
Work from the room outward: measure once, choose the material, add a deliberate allowance, and price it with your own numbers. Each step hands its result to the next.
- Step 01 Measure the room Floor area and perimeter from length and width. 12 × 10 ft 120 sq ft Open calculator
- Step 02 Choose the material Coverage, coats, and a visible allowance, rounded to whole cans. 332 sq ft of wall 3 gallons Open calculator
- Step 03 Price it your way Your shelf price and supplies, with no national averages. 3 gal × $42 $126 Open calculator
See the why
Every calculator shows its formula and a worked example that matches its default result.
Adjust the reality
Coverage, price, and allowance stay editable because products and rooms differ.
Keep it private
Calculations run in your browser with no account and no stored measurements.
Guides for the measuring part.
Short, practical answers for the decisions calculators cannot make for you.
How much paint do I need?
Understand wall area, coats, openings, coverage, and the allowance that changes the answer.
How many boxes of flooring do I need?
Turn square footage into cartons, see how waste and whole-box rounding add up, and avoid a short order.
How many tiles are in a square foot?
A tile-size reference table and the one-line formula behind it, for any tile in inches or centimeters.
How to calculate square footage of a room
Measure rectangles, split L-shaped rooms, and convert between square feet, square yards, and square meters.
4x8 vs 4x12 drywall sheets
Compare sheet counts, seams, and handling for the two most common drywall sizes.
What size TV for my room? Viewing distance explained
How the 30° and 40° viewing-angle guidelines turn into seating distances and screen sizes.