Interior Design Calculators
Curtain Fabric Calculator
Calculate the fabric yardage and panel count needed for curtains from window size, fullness ratio, hem allowance, and fabric bolt width.
Furniture Layout Calculator
Calculate clear floor space and an estimated walkway width after furniture placement, compared against standard clearance guidelines.
Furniture Scale Calculator
Convert an actual furniture or room dimension into a scaled drawing dimension for a floor plan using a chosen scale ratio.
Interior Design Space Planner
Calculate what percentage of a room's floor area is used by furniture and how much open space remains, against a comfortable-layout guideline.
Interior Lighting Design Calculator
Calculate the total lumens needed for a room's general lighting based on its area and a recommended foot-candle level for that room type.
Lumen Requirement Calculator
Calculate the total lumens needed for a room from its area and a custom required foot-candle lighting level for any use case.
Paint Quantity Calculator
Calculate the gallons of paint needed for a room from total wall area, door and window area to subtract, and the number of coats.
Room Color Scheme Calculator
Generate complementary, triadic, analogous, split-complementary, or tetradic color scheme hues from a single base color hue value.
Rug Size Calculator
Find the largest standard area rug size that fits a room while leaving a recommended floor border between the rug edge and the walls.
Wall Art Spacing Calculator
Calculate the even gap width needed to space multiple art pieces evenly across a wall based on wall width and each piece's width.
The Proportions That Make a Room Feel Right
Interior design decisions that feel purely aesthetic — rug size, art placement, lighting brightness — actually follow fairly specific proportional rules that separate a room that feels balanced from one that feels off, even when it's hard to articulate exactly why. These calculators apply those established design ratios directly.
Popular Interior Design Calculators
Ten tools span layout, lighting, and textiles:
- Rug Size Calculator — recommends rug dimensions based on room size and furniture arrangement.
- Lumen Requirement Calculator — estimates total lighting output needed for a room based on its size and function.
- Furniture Layout Calculator — checks clearances and traffic flow for a proposed furniture arrangement.
- Curtain Fabric Calculator — calculates fabric yardage needed based on window size and desired fullness.
- Wall Art Spacing Calculator — finds correct height and spacing for hanging art relative to furniture and eye level.
Why Rug Size Mistakes Are So Common
The most frequent interior design sizing mistake is choosing a rug too small for the room — a common guideline is having at least the front legs of major furniture pieces resting on the rug, which visually anchors the seating area, while a too-small rug "floating" in the middle of a room makes the whole space feel disconnected and smaller than it is. This same anchoring logic extends to lighting: a single overhead fixture sized for a much smaller room leaves a large space under-lit no matter how bright the bulb, which is why lumen requirement calculations scale directly with square footage and room function rather than using a single fixture recommendation for every room size.
Frequently Asked Questions
How high should art actually be hung above furniture?
A common design guideline places the center of the artwork at eye level (around 57–60 inches from the floor) when hung alone, or about 6–8 inches above furniture when hung above a sofa or console.
Do lumen requirements change by room type?
Yes significantly — task-oriented spaces like kitchens and home offices need considerably more lumens per square foot than a bedroom or living room designed for softer ambient light.
Explore More
Planning the structural side of a remodel? See the Home Improvement Calculators, or check outdoor space planning in the Landscaping Calculators.