Convert cubic feet and acre-feet, then check gallons or water depth over acres when that context helps.
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Table of contents
How to use our Cubic Feet to Acre-Feet Converter
- Choose the starting unit in Convert from: cubic feet to acre-feet or acre-feet to cubic feet.
- Enter the amount in Volume. Commas and spaces are OK, and zero is allowed.
- Open Advanced options if you want to change Decimal places, turn Also show US gallons on or off, or enter Land area for depth check.
- Click Calculate, then read Converted volume first. Use Formula used to confirm that the conversion direction was not reversed.
- Sanity-check the scale: 43,560 cubic feet should equal 1 acre-foot, and 1 acre-foot over 1 acre should show 12 inches in Depth over your land.
Definitions
Cubic foot: A volume that fills a cube 1 foot long, 1 foot wide, and 1 foot tall.
Acre-foot: A water-volume unit equal to 1 acre covered by 1 foot of water, or 43,560 cubic feet [3].
US liquid gallon: The gallon used for liquid volume in the United States; this converter uses it only for Same volume in US gallons.
Decimal places: The number of digits shown after the decimal point in Converted volume and supporting results.
Depth over your land: The average water depth in inches if the entered volume were spread evenly over the acres you entered.
Common mistakes and quick fixes
Mistake: Picking the wrong Convert from direction.
Fix: Check Formula used ; cubic feet to acre-feet divides by 43,560, while acre-feet to cubic feet multiplies by 43,560.
Mistake: Entering a negative or blank Volume .
Fix: Enter a Volume of 0 or more in the unit shown by Convert from .
Mistake: Reading a rounded Converted volume of 0 as truly zero.
Fix: Set Decimal places to Auto or a larger value, and check Rounding note if it appears.
Mistake: Entering square feet, gallons, or another unit in Land area for depth check .
Fix: Enter land area in acres only, or leave Land area for depth check blank to hide Depth over your land .
Mistake: Treating Same volume in US gallons as the main acre-foot answer.
Fix: Use Converted volume for the official unit conversion and Same volume in US gallons only as a water-volume check.
Limitations & Key Assumptions / Boundary Conditions
- The converter accepts only non-negative volume. It does not model flowing water, storage losses, seepage, evaporation, or storm timing.
- Depth over your land assumes the water is spread evenly over the entered acres. Real ground slope, soil, drains, and low spots can make actual depth uneven.
- Same volume in US gallons uses US liquid gallons, not imperial gallons or dry gallons.
- Rounding changes what is displayed, not the underlying conversion. Use Auto or more decimal places for very small acre-foot values.
- Very large values are formatted for readability. They are still simple unit conversions, not engineering design results.
Methodology
Core conversion
The converter uses the standard relationship that 1 acre-foot equals 43,560 cubic feet. If Convert from is cubic feet to acre-feet, it divides by 43,560. If Convert from is acre-feet to cubic feet, it multiplies by 43,560.
acre_feet = cubic_feet / 43560
cubic_feet = acre_feet * 43560
Gallons check
When Also show US gallons is on, the calculator first finds the cubic-feet amount, then converts that amount to US liquid gallons. One cubic foot has 1,728 cubic inches, and one US liquid gallon has 231 cubic inches.
gallons = cubic_feet * (1728 / 231)
Depth over land
When Land area for depth check is entered, the calculator first finds the acre-feet amount. One acre-foot spread over 1 acre is 1 foot deep, so the depth in feet is acre-feet divided by acres. The calculator then multiplies by 12 to show inches.
depth_inches = (acre_feet / land_area_acres) * 12
Rounding and display
Decimal places controls the displayed answer. Auto keeps useful digits and avoids making small nonzero acre-foot answers look like zero when possible. If a manually rounded Converted volume would display as 0 while the exact value is positive, the calculator shows Rounding note.
Mini-example
For 1,000,000 cubic feet, the main conversion is:
acre_feet = 1000000 / 43560 = 22.9568411387
If that same volume is spread over 2.5 acres, the depth check is:
depth_inches = (22.9568411387 / 2.5) * 12 = 110.1928374656
So the converter shows about 22.9568 acre-feet and about 110.19 inches over 2.5 acres, depending on the selected rounding.