How Many Acres? Acreage Calculator for Land

This acreage calculator answers how many acres a piece of land covers. Give it the length and width of a rectangular lot, the base and height of a triangular one, or an area you already know, and it gives the area in acres.

A known area can be in square feet, square metres, hectares or square miles, and the result also comes in the other units people use for land.

The acre is a strange unit to picture. It is not a square of any round size: an acre is 43,560 square feet, and a square of that size has sides that are not a whole number of feet. Historically it was a strip one furlong (660 feet) long and one chain (66 feet) wide, which is why the calculator's default is 660 by 66 feet and comes out at exactly one acre.

The acre here is the international acre, based on the foot of exactly 0.3048 metres. The older US survey acre, used in some land records until the US survey foot was retired at the end of 2022, is larger by about four parts in a million, which matters only on very large surveyed tracts.

1. Choose how to work: from length and width, from a triangle, or from an area you already know.
2. For dimensions, choose feet, yards, metres or miles, and enter the two measurements.
3. For a known area, enter it and choose its unit.
4. Read the acres at the top, and the same area in hectares, square feet, square metres, square yards and square miles below.

The presets convert one hectare to acres, work out a 660 by 330 foot lot, a 100 by 150 foot house lot and a triangular plot.

1. Find the area. A rectangle is length times width. A triangle is half the base times the height. A known area is taken as entered.

1. Convert to square metres. Every unit is converted through its exact size: a square foot is 0.09290304 m², a square yard 9 square feet, a square mile 27,878,400 square feet, a hectare 10,000 m².

1. Convert to acres and the other units. An acre is 43,560 square feet, so acres are square feet divided by 43,560. The same area is shown in hectares, square feet, square metres, square yards and square miles.

1. Round for display. Acres and hectares show four decimal places, square miles six.

The default is a strip 660 feet by 66 feet:

1. Area: 660 × 66 = 43,560 square feet.
2. Acres: 43,560 ÷ 43,560 = 1 acre.
3. Hectares: 0.4047 ha, or 4,046.9 square metres.

A lot 660 by 330 feet is 217,800 square feet, which is 5 acres (2.0234 hectares).

A house lot 100 by 150 feet is 15,000 square feet, or 0.3444 acres.

A triangular plot with a 400 foot base and a 300 foot height is 60,000 square feet, or 1.3774 acres.

One hectare is 10,000 square metres, which is 2.4711 acres.

Measure the boundaries, or take them from your deed or plat, and enter them. For a rectangle, length times width in feet divided by 43,560 is the acreage. For an irregular lot, split it into rectangles and triangles, run each one and add the acres.

Your deed or a survey usually states the acreage; this calculator is useful for checking it, or for working out part of a property such as a pasture or a garden.

Exactly 43,560 square feet, or 4,840 square yards. Any shape with that area is an acre: the default 660 by 66 foot strip is one, and so is a square of the same area.

2.4711 acres. A hectare is 10,000 square metres, a square 100 metres on a side. Going the other way, an acre is 0.4047 hectares. For Spanish speakers asking cuántos acres hay en una hectárea, the answer is the same: 2.4711. The table below converts common sizes both ways.

Sketch the lot from the plat or from your own measurements and draw straight lines that cut it into rectangles and triangles. Measure each piece: the two sides of each rectangle, and the base of each triangle with its height taken square to the base. Run each piece through the calculator and add the acres together.

A four-sided lot whose sides are not parallel can always be split into two triangles by drawing one diagonal; measure the diagonal as the shared base and the distance from each far corner to it as the heights. The more pieces you use, the closer the answer gets to a survey, but a deed or a licensed surveyor is still the authority on the legal acreage.

• Slopes. Land area is measured on the horizontal, as surveys do. A hillside has more ground surface than its acreage.
• Irregular boundaries. Curved or many-sided lots need to be broken into rectangles and triangles, or measured by a surveyor.
• The US survey acre. Older land records may use the survey foot. The difference is about four parts in a million.
• Legal descriptions. The acreage in a deed is a legal matter. This calculator does not replace a survey.

• Dividing by 43,000 or 44,000. The figure is 43,560.
• Mixing feet and metres. Choose one unit for both measurements.
• Using the length of a sloped side as a triangle's height. The height is measured square to the base.
• Assuming an acre is a square. Any shape of 43,560 square feet is an acre.

• NIST Handbook 44, Appendix C, General Tables of Units of Measurement: the acre of 43,560 square feet and the square mile of 640 acres. nist.gov/pml/owm/nist-handbook-44-current-edition
• NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B: the acre and the hectare in square metres. nist.gov/pml/special-publication-811
• NIST, The US Survey Foot: superseded by the international foot from January 1, 2023, except for historic and legacy applications. nist.gov/pml/us-surveyfoot