1. Select your shape
Choose from rectangle, circle, triangle, trapezoid, L-shape, annulus, or wall-and-window layouts to match your project.
What is rectangle border square footage?
Rectangle border square footage is the area of the border (frame) around a rectangular shape, measured in square feet. To calculate border area, subtract the inner rectangle area from the total outer rectangle area: Border Area = Total Area - Inner Area. This is used for walkways, garden borders, trim, and edging projects.
Getting started
How to Calculate Rectangle Border Square Footage
To calculate rectangle border area: 1) Calculate the inner area (Length x Width). 2) Add border width to each side to get outer dimensions. 3) Calculate outer area. 4) Subtract inner from outer. A 10x8 ft rectangle with a 1-foot border has a border area of 40 square feet.
2. Enter your measurements
Input dimensions in feet, inches, yards, meters, or centimeters. The Square Foot Calculator converts units automatically.
3. Get area and cost
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
Material pricing
Calculate Cost of Materials
Enter the price per square foot of material to estimate total cost. The calculator accepts pricing in square feet, square inches, square yards, or square meters and converts to the correct total based on your area.
There are 2 steps to calculate material cost:
- Enter the price per unit area. For tiling projects, enter the price per box and the number of square feet each box covers. For carpet, enter the cost per square yard. For flooring installation with hardwood or laminate, enter the cost per square foot.
- Select the unit of area that matches your pricing. The Square Foot Calculator multiplies your total area by the unit price to produce an estimated material cost, including labor costs when added to the per-unit price.
To calculate the volume of bulk materials like mulch or gravel for landscaping, convert area to cubic yards or cubic meters by multiplying the area by the depth of material.
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.
Basic Length Conversion
Convert other units of measure to feet with these 4 formulas:
| From | To Feet | Formula |
|---|---|---|
| Inches | Feet | Divide by 12 |
| Yards | Feet | Multiply by 3 |
| Meters | Feet | Multiply by 3.28084 |
| Centimeters | Feet | Divide by 30.48 |
For example, 48 inches ÷ 12 = 4 feet. A measurement of 5 meters × 3.28084 = 16.40 feet. The Square Foot Calculator handles these conversions automatically when you select the input unit.
Unit conversion
Area Conversion
Measure your space in inches or centimeters, calculate area in square inches or square centimeters, then convert to any unit you need, including square feet, square yards, square meters, or acres.
| Unit | Square Feet Equivalent |
|---|---|
| 1 sq ft | 144 sq in |
| 1 sq yd | 9 sq ft |
| 1 sq m | 10.764 sq ft |
| 1 acre | 43,560 sq ft |
A 300 sq ft room equals 33.33 sq yd, 27.87 sq m, or 43,200 sq in. The Square Footage Calculator displays all conversions at once so you can compare units for flooring, carpet, or tiling projects without manual math.
Shape formulas
Area Formulas for Different Shapes
The Square Foot Calculator supports 11 shape formulas for construction, interior design, landscaping, and flooring projects. Each formula below includes a diagram with labeled dimensions.
Rectangle Border Shape
Calculate square foot of a rectangle border
Using measurements in feet:
- Inner Area (ft²) = Length × Width
- Total Area (ft²) = (Length + 2 × Border Width) × (Width + 2 × Border Width)
- Border Area (ft²) = Total Area − Inner Area
Use this formula for painting a border, installing trim, or measuring a walkway around a rectangular garden. A 10 ft × 8 ft (3.05 m × 2.44 m) area with a 1-foot border has a border area of 40 sq ft.
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 calculate border area around a rectangle?
Calculate the outer rectangle area, subtract the inner rectangle area. Outer dimensions = inner dimensions + (2 x border width) on each side.
How much material do I need for a walkway around a pool?
Enter the pool dimensions as the inner rectangle and the walkway width as the border. The calculator gives you the walkway area for material ordering.
What is the formula for rectangle border area?
Border Area = (L + 2B)(W + 2B) - (L x W), where L = length, W = width, and B = border width. This subtracts the inner area from the outer area.
Can I use this for picture frame calculations?
Yes, enter the picture dimensions and frame width to find the frame material area. The calculator works for any rectangular border or frame.
How do I calculate garden edging area?
Enter the garden bed dimensions and the edging width. The border area tells you how much edging material you need.
What if the border width is different on each side?
This calculator uses uniform border width. For borders with different widths on each side, calculate each border strip separately as a rectangle and add the areas.