Interior project calculators
Turn room measurements into practical quantities for paint, wallpaper, drywall, flooring and tile—complete with waste, package rounding and live visual feedback.
Start with Wallpaper →Choose your project
Every calculator includes US and metric inputs, editable waste and package coverage, and a practical shopping list.
Measure once.
Order with evidence.
Enter each measurement directly, review the assumptions, and use the rounded package quantities to prepare the order.
- 1
Sketch the room shell
Record wall-to-wall length, width and height before thinking about product packs. Split alcoves, halls and height changes into separate rectangles so every number remains auditable.
- 2
Mark openings and fixed areas
Doors, large windows, cabinets and permanent fixtures affect different materials in different ways. Use each calculator's dedicated controls instead of applying one blanket deduction.
- 3
Finish with the product label
Enter the exact box, sheet, roll or can coverage and a layout-appropriate waste allowance. The final shopping list rounds to whole purchasable packages.
Interior calculator questions
Which measurements can I reuse across interior calculators?
Room length, width and wall height can often be reused, but each material needs different deductions and package information. Paint and wallpaper use wall area; flooring and tile use floor area; drywall can also include the ceiling.
Should I calculate the whole home as one area?
Separate rooms are easier to verify and let you handle different heights, finishes and waste rates. ProjectMeter combines multiple entries only after each room is measured.
Why do package counts round up?
Retailers sell complete cans, rolls, sheets and boxes. Rounding only the final combined requirement avoids suggesting an impossible partial package while reducing unnecessary over-rounding.