How this calculator works
One acre is 43,560 square feet. Find the area of the lot in square feet from its shape: length times width for a rectangle, half the base times the height for a triangle, and π times the radius squared for a circle. Divide by 43,560 to get acres, and multiply by 0.0929 for square meters.
Worked example: a lot 200 ft by 150 ft is 30,000 square feet, which is 0.689 acres (0.2787 hectares). A triangle with a base of 200 ft and a height of 150 ft is 0.344 acres, and a circle 200 ft across 0.721 acres.
Common lot sizes in acres
Rectangles.
| Lot | Square feet | Acres |
|---|---|---|
| 50 × 100 ft | 5,000 | 0.115 |
| 100 × 100 ft | 10,000 | 0.230 |
| 100 × 150 ft | 15,000 | 0.344 |
| 150 × 200 ft | 30,000 | 0.689 |
| 200 × 218 ft | 43,600 | 1.001 |
| 300 × 300 ft | 90,000 | 2.066 |
| 330 × 660 ft | 217,800 | 5.000 |
Tips before you buy
- An acre is 43,560 square feet. A football field without the end zones is about 1.1 acres.
- A quick check: 1/4 acre is 10,890 square feet, about 104 × 104 feet.
- Use the deed or survey for the true area, since measurements on the ground can be off.
- For a fertilizer, seed or lawn job, use the dedicated calculators, which work from the area.
- To convert to hectares multiply acres by 0.4047.
Tools & materials for this project
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Frequently asked questions
How many square feet are in an acre?
43,560. A square acre is about 208.7 feet on a side.
How do you calculate acres from length and width?
Multiply the length by the width in feet, and divide by 43,560. 200 ft × 150 ft = 30,000 ft² = 0.689 acres.
How big is a quarter acre?
10,890 square feet, about 104 feet by 104 feet, or 50 × 218 ft.
How many hectares in an acre?
About 0.4047 hectares. One hectare is 2.471 acres.
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Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.