How do I calculate room area?

Room area equals length multiplied by width. For a 12 ft × 10 ft room, the area is 120 square feet. This tool does the multiplication automatically and converts between unit systems.

What is room volume used for?

Room volume (length × width × height) is needed to size HVAC systems and air conditioners, calculate ventilation rates, and estimate heating or cooling loads. It is measured in cubic feet or cubic meters.

How much paint do I need for a room?

A standard gallon of paint covers about 350–400 square feet per coat. Calculate your four wall areas (perimeter × ceiling height) and add the ceiling area, then subtract windows and doors. Use the area result from this tool as a starting point.

Can I enter measurements in feet and inches?

Yes. Select Imperial units and enter feet as a decimal — for example, 10 feet 6 inches = 10.5 ft. Or just use the decimal feet field directly.

Why is my room area different from what the contractor quoted?

Contractors often measure to the center of walls or include closets and alcoves. This calculator uses the exact dimensions you provide. Always measure the actual floor space in the room for the most accurate result.

How do I convert square feet to square meters?

1 square foot = 0.0929 square meters. For quick mental math, divide square feet by 10.764. This tool shows both simultaneously so no manual conversion is needed.

Room Size Calculator

Enter room length, width, and optional height to instantly get area and volume in metric or imperial units.

Room Dimensions

Unit System

Length (ft)

Width (ft)

Ceiling Height (ft, optional)

Optional: Material Cost Estimate

Enter your flooring or carpet price per square unit to see total material cost.

Enter room dimensions on the left
to see area and volume results.

Summary

The Room Size Calculator instantly computes room area and volume from your entered length, width, and optional ceiling height. Switch between metric (meters) and imperial (feet/inches) units with a single click. Results include square footage, square meters, cubic feet, and cubic meters — everything you need for flooring, paint, carpet, and HVAC estimates.

How it works

Select your preferred unit system: imperial (feet/inches) or metric (meters/centimeters).
Enter the room length and width in the input fields.
Optionally enter the ceiling height to calculate room volume.
Results update instantly — area and volume are shown in both unit systems.
Use the per-unit cost fields to estimate flooring or carpet material costs.

Use cases

Calculate square footage for flooring material orders.
Estimate paint coverage needed for walls and ceilings.
Determine carpet area before purchasing rolls.
Size HVAC units and ventilation requirements.
Plan furniture layout by knowing exact room dimensions.
Estimate insulation needs based on room volume.
Convert between metric and imperial room measurements.
Provide room dimensions when getting contractor quotes.

Frequently Asked Questions

Last updated: 2026-05-29 · Reviewed by Nham Vu

Room Size Calculator

Room Dimensions

Floor Area

Room Volume

Wall Area (all 4 walls)

Material Cost Estimate

Dimension Summary

Summary

How it works

Use cases

Frequently Asked Questions

Room Size Calculator

Use the Room Size Calculator

Room Dimensions

Floor Area

Room Volume

Wall Area (all 4 walls)

Material Cost Estimate

Dimension Summary

Summary

How it works

Use cases

Frequently Asked Questions