Useful Tables and Calculations

Weights and Measures

Liquid

1 mililiter (ml) = 1 cubic centimeter (cc)

1 teaspoon (tsp) = 5 milliliter (ml)

3 teaspoons (tsp) = 1 tablespoon (Tbsp)

1 tablespoon (Tbsp) = 15 milliliter (ml)

2 tablespoons (Tbsp) = 1 ounces (oz)

16 tablespoons (Tbsp) = 1 cup (c.)

1 cup (c.) = 8 ounces (oz)

2 cups (c.) = 1 pint (pt)

1 pint (pt) = 16 ounces (oz)

2 pints (pt) = 1 quart (qt)

8 pints (pt) = 1 gallon (gal)

1 gallon (gal) = 128 ounces (oz)

1 gallon (gal) = 3785 mililiters (ml)

Weight

1 ounce (oz) = 28.4 grams (gm)

16 ounces (oz) = 1 pound (lb)

1 pound (lb) = 454 grams (gm)

1 kilogram (kg) = 2.2 pounds (lbs)

Length and Area

1 mile (mi) = 5,280 feet (ft)

1 mile (mi) = 320 rods

1 rod = 16.5 feet (ft)

1 mile (mi) = 1.6 kilometers (K)

1 acre (A) = 43,560 square feet (sq ft)

1 square rod (sq rod) = 272.3 square feet (sq ft)

1 acre (A) = 160 square rods (sq rod)

Pints of Commercial Material Needed Per Acre

for given amounts of active ingredient (ai)

lb ai/gal of commercial material

Recommended rate in pounds of active ingredient per acre (lbs of ai/A)

0.25

0.5

0.75

1.0

1.5

2.0

Pints of commercial material per acre

1.00

2

4

6

8

12

16

2.00

1

2

3

4

6

8

2.64

0.75

1.5

2.25

3

4.5

6

3.00

0.7

1.33

2

2.7

4

5.33

3.34

0.6

1.2

1.8

2.4

3.6

4.8

4.00

0.5

1

1.5

2

3

4

5.00

0.4

0.8

1.2

1.6

2.4

3.2

6.00

0.33

0.7

1

1.33

2

2.7

6.70

0.3

0.6

0.9

1.2

1.8

2.4

7.00

0.29

0.57

0.87

1.14

1.7

2.3

8.00

0.25

0.5

0.75

1.0

1.5

2.0

Amount of Chemical Needed

for 1 sq rod and 1,000 sq ft
Applied at the rate of 1 lb of ai/A

Liquid

lb ai/gal

milliliters (ml)

per sq rod

per 1,000 sq ft

0.67

35

130

1.00

24

87

1.50

16

58

2.00

12

43

2.50

10

35

3.00

8

29

3.34

7

26

4.00

6

22

6.00

4

14

7.00

3.5

12

Dry

percent (%) ai

grams (g)

per sq rod

per 1,000 sq ft

100

2.8

10

90

3.1

12

80

3.5

13

75

3.8

14

70

4.0

15

65

4.4

16

60

4.7

17

50

5.6

21

40

7.0

26

30

9.4

35

20

14.1

52

10

28.3

104

5

56.6

208

4

71.0

261

3

94.6

347

2

142.0

521

1

284.0

1,042

How to Determine the Amount of Herbicide Needed

  • If rate is recommended for
    Liquid commercial product:

    Rate of product/acre x acres treated = total volume

    Example: 1.5 pt/A x 20 A = 30 pt product

30 pt ÷ 8 pt/gal = 3.75 gal product

  • If rate is recommended as
    Active ingredient (ai) for liquid product:

    Rate of ai/A ÷ lb ai/gal product = gal product/A

    Gal product/A x A treated = total gallons product

    Example: 0.5 lb ai ÷ 4 lb ai/gal = 0.125 gal/A

0.125 gal/A x 20 A = 2.5 gal product

  • If rate is recommended for
    A dry commercial product:

    Rate of product/A x A treated = total weight

    Example: 15 lb/A x 50 A = 750 lb product
  • If rate is recommended as
    Active ingredient (ai) for a dry product

    Rate of ai/A ÷ lb ai/lb product = lb product/A
    lb product/A x acres = total weight

    Example: 2 lb ai/A ÷ 0.8 lb ai/lb product = 2.5 lb product/A

2.5 lb/A x 30 A = 75 lb product

Method for Applying Correct Amount of Spray Solution per Acre

To determine the spray volume of a hydraulic sprayer, use the following short-cut calibration formulas. Other calibration methods and descriptions are in Spray Equipment and Calibration, Bulletin EXT 658, available through the University of Idaho Bulletin Office.

1. Determine application speed in miles per hour (mph)

mph = (feet traveled ÷ time in seconds) x 0.6818

2. Determine nozzle output in gallons/minute (gal/min)

gal/min = ounces collected ÷ (2.13 x seconds)

3. Determine sprayer output in gallons/acre (gal/A)

gal/A = [(5,940 x gal/min per nozzle) ÷ (nozzle spacing in inches x mph)]

* Based on 2,4 D formulation with a 4 lb acid equivalent (ae)/gal


Teaspoon Volume Equivalents

To prepare one gallon of spray solution (using standard kitchen measuring spoons, level measure)

Chemical

Rate per Acre

Volume water per Acre

Tablespoons of chemical for
1 gallon of spray solution

2,4 D amine *

3 pint (1.5 lb)

50 gallons

2.0

2,4 D amine *

1 pint (0.5 lb)

10 gallons

3.2

2,4 D low-volatile ester *

3 pint (1.5 lb)

50 gallons

2.0

2.4 D low-volatile ester *

1 pint (0.5 lb)

10 gallons

3.2

glyphosate

2 quart (1.5 lb)

50 gallons

2.6

naptalam

2 gallons (4.0 lb)

50 gallons

10.2