International Feet to Acres Converter

This calculator converts an area measured in international feet (square feet) into acres. Enter the area in square feet, and you get the equivalent in acres, using the standard international conversion factor of 43,560 square feet per acre.

Formula

The conversion is a simple division:

Acres = Square feet ÷ 43,560

Where:

• Square feet is the area you want to convert, measured in international feet (the standard foot used worldwide, exactly 0.3048 meters).
• Acres is the resulting area in acres (the international acre, exactly 4,046.8564224 square meters).
• 43,560 is the number of square feet in one acre. This is a fixed constant.

Worked Example

Using the default value of 87,120 square feet:

1. Write down the formula: Acres = Square feet ÷ 43,560
2. Plug in the number: Acres = 87,120 ÷ 43,560
3. Do the division: 87,120 ÷ 43,560 = 2

The result is exactly 2.0000 acres. The calculator shows 2.0000 acres (4 decimal places), matching this calculation.

Why “International” Feet Matter

The term “international foot” distinguishes the modern standard from the older U.S. survey foot. In 1959, the United States, the United Kingdom, Canada, Australia, New Zealand, and South Africa agreed to define the international foot as exactly 0.3048 meters. Before that, the U.S. used a slightly different survey foot (about 0.3048006 meters). For most land measurements the difference is tiny—about 2 parts per million—but for very large areas or precise engineering work, the distinction matters. This calculator uses the international foot, which is the standard for most modern applications.

When to Use This Conversion

You would use this conversion in real estate, agriculture, construction, and land management, whenever you have an area given in square feet and need to express it in acres. For example:

• Understanding a property listing that gives lot size in square feet but you want acres.
• Planning a farm or ranch, where field sizes are often quoted in acres.
• Comparing land parcels that are listed in different units.
• Estimating the area of a building site for zoning or permitting.

How to Read the Result

The result is the area in acres, expressed as a decimal. For example, 0.5 acres means half an acre, 1.25 acres means one and a quarter acres. If you want to convert back, multiply the acres by 43,560 to get square feet. Note that an acre is a unit of area, not length, so it does not have a fixed shape—a 1-acre plot could be a rectangle 200 feet by 217.8 feet, or any other shape with the same area.

Common Mistakes and Limits

• Using the wrong foot: If your measurement uses U.S. survey feet, the result will be off by a tiny fraction. For most purposes this is negligible, but for precise legal surveys, check which foot was used.
• Mixing units: This calculator expects square feet. If you have dimensions in feet (length × width), multiply them first to get square feet, then enter that number.
• Rounding too early: If you round the square feet to a whole number before converting, you lose precision. Keep as many digits as you have.
• Confusing acres with square miles: There are 640 acres in a square mile, not 43,560. That number is for square feet.

The formula is exact, but the result is only as accurate as the input. If your square footage is an estimate (e.g., from a pacing or a rough sketch), the acreage will also be an estimate.

Alternatives and Related Units

If you are working with metric units, you might want to convert square meters to hectares instead: 1 hectare = 10,000 square meters, and 1 acre ≈ 0.4047 hectares. For very large areas, square miles or sections (1 section = 1 square mile = 640 acres) are common in the U.S. For small plots, square feet or square yards (1 square yard = 9 square feet) are often used. This calculator focuses on the international foot-to-acre conversion, but the same constant (43,560) applies regardless of the shape of the area.

Frequently Asked Questions

How many square feet are in an acre?

Exactly 43,560 square feet. This is the international acre definition, and it is the same in the U.S. customary and imperial systems.

What is the difference between an international foot and a U.S. survey foot?

The international foot is exactly 0.3048 meters, defined in 1959. The U.S. survey foot is slightly longer: 1200/3937 meters, about 0.3048006 meters. The difference is about 2 parts per million, so for a 1-acre plot, the difference is about 0.04 square feet—negligible for most purposes.

Can I use this calculator for irregularly shaped plots?

Yes, as long as you know the total area in square feet. The conversion does not depend on shape. If you only have length and width, multiply them to get square feet (for rectangles), or use a surveyor for irregular shapes.

Is an acre the same in all countries?

Most countries that use the acre use the international acre, which is exactly 4,046.8564224 square meters. Some countries have historical variants, but the international acre is the standard for international trade and most modern use.

How do I convert acres back to square feet?

Multiply the number of acres by 43,560. For example, 0.5 acres × 43,560 = 21,780 square feet.

Related

• Acre Feet to Cubic Kilometers Conversion
• Hourly to Minute Calculator: Convert Hours to Minutes
• Acres to Cubic Feet? Area vs Volume Explained

in sqft | Area | sq ft | 87120 | 0
out acres | Area in acres | acres | sqft / 43560 | 4