1. Measure in feet and inches
Use your tape measure to record both feet and inches for each dimension. Enter the values directly into the calculator without converting first.
What is a feet-and-inches measurement?
A feet-and-inches measurement combines two units on the same tape measure. For example, 7 ft 4 in means 7 whole feet plus 4 additional inches. To calculate square footage from feet and inches, convert the inches to a decimal fraction of a foot (divide by 12), then multiply length by width. This dual-unit format is the standard reading on most US tape measures and is used in construction, real estate, and interior design.
Getting started
How to Calculate Square Feet from Feet and Inches
To calculate square footage from feet and inches, first convert each measurement to decimal feet. Divide the inches portion by 12 and add it to the feet value. Then multiply length by width. For example, a space measuring 10 ft 6 in by 8 ft 3 in converts to 10.5 ft by 8.25 ft, giving an area of 86.625 square feet.
2. Select your shape
Choose Rectangle, Room, or Square from the shape dropdown. The calculator adjusts input fields to match your selection.
3. Get precise square footage
View results in square feet, square yards, square meters, and acres. Add a material price per unit to estimate total project cost.
Quick reference
Reference
1 acre = 43,560 square feet
1 square yard = 9 square feet
1 square meter = 10.764 square feet
1 square inch = 0.00064516 square feet
Core formula
Basic Formula for Area
Area is the amount of space occupied by a 2-dimensional shape. The shape could be a floor, a wall, a playground, or a field. The simplest formula for area applies to any rectangular shape:
Area = Length × Width
Measure the length and width of the space in feet. Multiply the two values to get the area in square feet. A rectangular room that is 12 feet (3.66 meters) long and 10 feet (3.05 meters) wide has an area of 120 sq ft (11.15 sq m).
Square yardage is area measured in yards, and square meters is area measured in meters. Measure in feet, find the area in square feet, then convert to the unit you need.
For an L-shape room, split the floor into 2 rectangular sections, calculate each area, and add the results. Convert all measurements to the same unit before multiplying, if your dimensions are in different units like inches and feet.
Shape formulas
Area Formulas for Different Shapes
The Square Foot Calculator supports multiple shape formulas for construction, interior design, landscaping, and flooring projects. Each formula below includes a diagram with labeled dimensions.
Rectangle Shape
Calculate square foot of a rectangle
Using measurements in feet: Area (ft²) = Length × Width. This is the most common formula for calculating square footage of a rectangular room, floor, wall, or field. A room 15 feet (4.57 meters) long and 12 feet (3.66 meters) wide has a Rectangle Area of 180 sq ft (16.72 sq m).
Room Shape
Calculate square foot of a room
Using measurements in feet: Area (ft²) = Room Length × Room Width. Measure the longest wall for length and the perpendicular wall for width. A standard rectangular room that is 12 feet (3.66 meters) long and 10 feet (3.05 meters) wide has an area of 120 sq ft (11.15 sq m). Door and window openings do not reduce floor area because the floor extends under the opening. For rooms with closets or alcoves, measure each rectangular section separately and add the areas together.
Waste factor
Adding 10% Surplus for Materials
Add a 10% surplus to your calculated area to account for material waste during cutting, breakage, and pattern matching. This waste factor applies to flooring, carpet, tiling projects, and landscaping materials.
Original Area
100 sq ft
+10%
Order Amount
110 sq ft
Total Material = Area × 1.10
A room with 200 sq ft of floor area needs 220 sq ft of material: 200 × 1.10 = 220 sq ft. Increase the surplus to 15% (multiply by 1.15) for diagonal flooring installation patterns or complex tiling projects with many cuts. The Square Foot Calculator includes a waste factor field for this calculation.
FAQ
Frequently Asked Questions
How do I convert feet and inches to square feet?
Convert inches to a decimal fraction of a foot by dividing by 12, then add to the feet value. For example, 5 feet 6 inches = 5.5 feet. Multiply length by width to get square feet: 5.5 ft × 4.25 ft = 23.375 sq ft.
How do I enter 5 feet 6 inches?
Enter 5 in the feet field and 6 in the inches field. The calculator converts this to 5.5 feet automatically. You can also enter 5.5 directly in the feet field if you prefer decimal input.
What is 10 ft 3 in × 8 ft 6 in in square feet?
10 ft 3 in = 10.25 ft and 8 ft 6 in = 8.5 ft. Multiply: 10.25 × 8.5 = 87.125 square feet. Use the Feet and Inches Calculator to compute this instantly.
Why do I need a feet and inches calculator instead of a regular one?
Many tape measures display feet and inches together (e.g., 7 ft 9 in). A dual-unit calculator lets you enter these measurements directly without manual conversion, reducing errors and saving time.
How do I convert inches to feet for square footage?
Divide the inch value by 12 to get feet. For example, 42 inches ÷ 12 = 3.5 feet. Then multiply length × width in feet to get square feet. The calculator handles this conversion automatically.
Can I mix feet and inches with other units?
Yes. The Feet and Inches Square Foot Calculator converts all inputs to feet before calculating. You can enter one dimension in feet and inches and another in yards or meters — the calculator unifies everything automatically.