Math for gardeners: Formulas you can use

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

Math comes into play whenever you are gardening. Calculating cubic yards of compost for example, or the area of a garden bed. Smartphones are helpful tools for calculating, but sometimes you need an actual formula or a little geometry. Here are some helpful formulas for gardeners.

Area measures

1 square inch (in.²) = 6.45 cm² = 0.0069ft²

1 square foot (ft²) = 144 in² = 0.111 yd²

1 square yard (yd²) = 9 ft² = 1,296 in²

1 acre (ac) = 43,560 ft² = 4,840 yd²

1 square mile = 640 ac = 3,097,600 yd²

Cubic measures

1 cubic inch (in.³) = 0.00058 ft³ = 0.0043 U.S. gal

1 cubic foot (ft³) = 0.037 yd³ = 7.48 U.S. gal

1 cubic foot (ft³) of water = 62.43 lb

1 cubic yard (yd³) = 27 ft³ = 202 U.S. gal

Weights

1 ounce (oz) = 28.35 g = 0.0625 lb

1 pound (lb) = 16 oz = 453.59 g

1 ton (U.S.) = 2,000 lb = 32,000 oz

Volume

1 fluid ounce (fl oz) = 0.00781 gal = 29.573 ml

1 cup (c) = 8 fl oz = 0.5 pt = 236.59 ml

1 pint (pt) U.S. = 16 fl oz = 2 c = 0.125 gal

1 quart (qt) = 2 pt = 4 c = 32 fl oz = 0.25 gal

1 gallon (gal) = 4 qt = 8 pt = 16 c = 128 fl oz

Linear measures

1 inch (in.) = 25.4 mm = 2.54 cm = 0.083 ft

1 foot (ft) = 12 in. = 0.3333 yd = 30.48 cm

1 yard (yd) = 36 in. = 3 ft = 0.9144 m

1 mile (mi) = 5,280 ft = 1,760 yd

Geometric calculations

Area of a rectangle = length (l) x width (w)

Area of a triangle = base (b) x height (h) / 2

Area of a circle = 3.14 x radius (r)²

Volume of a cone = 3.14 x r² x h / 3

Volume of a hemisphere = (2/3) x 3.14 x r³