An acre is the standard unit for land in the US, and it is still widely used in the UK, Canada and Australia alongside hectares. This acreage calculator converts the dimensions of a lot, garden or field into acres, and shows the same area in square feet, square yards, square metres and hectares. It also handles irregular lots, which are far more common than perfect rectangles.
How to calculate acreage
Work out the area in square feet, then divide by 43,560:
Acres = square feet ÷ 43,560
- Find the boundary lengths. Use your plat map, survey or deed if you have one, or measure with a long tape or measuring wheel.
- Choose the closest shape. Many suburban lots are rectangles or trapezoids (a different width at the front and back).
- For irregular lots, split the land into triangles using a diagonal, and measure all three sides of each. The Triangle (3 sides) option uses Heron’s formula, so you don’t need to measure any heights. Add each triangle to the total.
- Read the result in acres, with square feet and hectares alongside.
How big is an acre?
- 43,560 square feet, or 4,840 square yards
- 4,046.86 square metres, or 0.4047 hectares
- A square about 208.7 ft on each side
- About 76% of an American football field including the end zones (360 × 160 ft)
Worked example
A rectangular lot is 75 ft wide and 140 ft deep: 75 × 140 = 10,500 sq ft, and 10,500 ÷ 43,560 = 0.241 acres.
A lot that is 60 ft wide at the street, 80 ft wide at the back and 150 ft deep is a trapezoid: (60 + 80) ÷ 2 × 150 = 10,500 sq ft, which is also 0.241 acres.
Common lot sizes in acres
| Lot size (feet) | Square feet | Acres | Hectares |
|---|---|---|---|
| 50 × 100 ft | 5,000 | 0.115 | 0.046 |
| 50 × 150 ft | 7,500 | 0.172 | 0.07 |
| 60 × 120 ft | 7,200 | 0.165 | 0.067 |
| 75 × 100 ft | 7,500 | 0.172 | 0.07 |
| 75 × 150 ft | 11,250 | 0.258 | 0.105 |
| 100 × 100 ft | 10,000 | 0.23 | 0.093 |
| 100 × 150 ft | 15,000 | 0.344 | 0.139 |
| 100 × 200 ft | 20,000 | 0.459 | 0.186 |
| 150 × 300 ft | 45,000 | 1.033 | 0.418 |
| 208.71 × 208.71 ft | 43,560 | 1 | 0.405 |
| 330 × 660 ft | 217,800 | 5 | 2.023 |
| 660 × 660 ft | 435,600 | 10 | 4.047 |
Measuring a lot yourself
- Start with paperwork. Your deed, plat map or a previous survey lists the boundary lengths, which you can enter directly.
- Use a measuring wheel for long boundaries. Walk in a straight line from corner marker to corner marker.
- Check online maps. Many counties publish GIS parcel maps with measuring tools, which are useful for a quick estimate.
- Split odd shapes into triangles. Measure the diagonal between two opposite corners as well as the sides, and you can calculate any four-sided lot as two triangles.
- Subtract what you don’t need. To find the area of lawn, add the whole lot, then subtract the house, driveway and patio with the Subtract option.
Acres to other units
- 1 acre = 43,560 sq ft = 4,840 sq yd
- 1 acre = 4,046.86 m² = 0.4047 hectares
- 640 acres = 1 square mile
Acres, hectares and square metres
Most countries outside the US measure land in hectares. One hectare is 10,000 m², or about 2.471 acres. In the UK and Canada you will often see both units on property listings, while Australian rural listings commonly use hectares and suburban blocks use square metres. The calculator shows acres and hectares side by side.
Check against official records
A tape or wheel measurement is fine for planning a fence, a lawn treatment or a garden. For buying, selling, building or settling a boundary question, rely on a licensed land surveyor and your recorded plat. Lots are measured horizontally, so slopes, curves and easements can make a measured figure differ from the legal acreage.
Frequently asked questions
How many square feet are in an acre?
One acre is exactly 43,560 square feet.
How do I calculate acres from feet?
Multiply the length by the width in feet to get square feet, then divide by 43,560. A 100 × 200 ft lot is 20,000 sq ft, or 0.459 acres.
How many acres is a 100 × 100 ft lot?
A 100 × 100 ft lot is 10,000 sq ft, which is 10,000 ÷ 43,560 = 0.23 acres.
What are the dimensions of one acre?
An acre has no fixed shape. As a square it is about 208.7 × 208.7 ft; it could equally be 66 × 660 ft, the traditional furlong-long strip.
How do I find the acreage of an irregular lot?
Split the lot into triangles with straight lines between its corners, measure all three sides of each triangle, and add them with the Triangle (3 sides) option. The total is the lot area.
What is the difference between an acre and a hectare?
A hectare is 10,000 m², about 2.471 acres. An acre is about 0.4047 hectares.
How big is a typical house lot?
It varies hugely by region. Many suburban lots in the US are a quarter acre (10,890 sq ft) or smaller, while rural lots can be several acres.
How do I convert acres to square feet?
Multiply the acres by 43,560. For example, 0.75 acres × 43,560 = 32,670 sq ft. To go the other way, divide square feet by 43,560.