Bed Size Calculator
Compare mattress sizes in inches and centimetres and see how much floor space each one leaves in your room.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Bed dimensions are nominal references and can vary by region, maker and product. This estimate assumes the bed length follows the room length; check the frame and mattress maker’s dimensions before buying.
Worked example
calculated with the default values below
Bed size Queen (60 × 80 in) · Room length 12 ft · Room width 10 ft Bed width 60 in · Bed length 80 in · Bed width 152.4 cm · Bed length 203.2 cm · Floor space left in the room 86.7 sq ft · Walkway at the foot of the bed 64.0 in
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
F = L_r × W_r − w × l ÷ 144
- w
- Bed width, in
- l
- Bed length, in
- L_r
- Room length, ft
- W_r
- Room width, ft
- F
- Free floor area, ft²
Nominal regional/product dimensions in inches; 1 sq ft = 144 sq in. The bed must fit room length × width in either orientation. Walkway follows the bed dimension along room length; other furniture and side clearance are excluded.
Frequently asked questions
How much floor area remains in a 12 by 10 foot room with a king bed?
The calculator subtracts the mattress footprint from room area. Its US king is 76 × 80 inches, or about 42.2 square feet, leaving about 77.8 square feet in a 120 square foot room. The separate walkspace output subtracts bed length from room length, giving 64 inches for a 12 foot room. It does not assess clearance at both sides or account for other furniture.