Rectangle Border Calculator — Frame Area Tool

Q: 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.

Q: 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.

Q: 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.

What is rectangle border square footage?

Rectangle border square footage equals total outer rectangle area minus inner rectangle area. Apply Area = (outer length × outer width) − (inner length × inner width). For full-area rectangles, use the rectangle calculator; for a walkway around the border, see the driveway calculator.

Getting started

How to Calculate Rectangle Border Square Footage

To calculate rectangle border square footage, measure the outer rectangle length and width and the inner rectangle dimensions in feet. Subtract inner area from outer area. Useful for picture frames, garden borders, and room moldings.

1. Measure outer rectangle

Measure outer length and width including the border in feet.

2. Measure inner rectangle

Measure the inner empty rectangle dimensions in feet.

3. Subtract inner from outer

Border area = outer area − inner area.

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

Rectangle border area times price per unit equals material cost. Apply to picture frames, garden edging, or wall trim.

There are 2 steps to calculate material cost:

Enter the cost per square foot or per linear foot of the border material — trim, edging, sod, or pavers.
The Square Foot Calculator multiplies the border area by your unit price for material total.

Borders have 4 corners that need miter cuts. Add 10-15% extra material for angled joins.

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.

REFERENCES

Rectangle Border
Calculator — Frame Area Tool

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