U.S.
to Metric Measurements
- Inches (")(in) x 25.4 = millimeters (mm)
- Inches (")(in) x 2.54 = centimeters (cm)
- Inches (")(in) x 0.0254 = meters (m)
- Feet (')(ft) x 0.3048 = meters (m)
- Yards (yds) x 0.9144 = meters (m)
- Miles (mi) x 1.6093 = kilometers (km)
- Feet (')(ft) x 0.0003048 = kilometers (km)
- Gallons (gals) x 3.78 = liters (l)
- Cubic feet x 28.316 = liters (l)
- Pounds (P) x 0.4536 = kilograms (kg)
- Square inches x 6.452 = square centimeters
- Square feet x 0.0929 = square meters
- Square miles x 2.59 = square kilometers
- Acres x 4046.85 = square meters
- Cubic inches x 16.39 = cubic centimeters
- Cubic feet x 0.0283 = cubic meters
Area and Distance Conversions
- Acre x 43560 = square feet
- Inches x 0.0833 = feet
- Feet x 12 = inches
- Square mile ("Sections") x 640 = Acres
- Miles x 5280 = feet
- Circumference of circle x 0.3183 = Diameter of the
circle
- Diameter of circle x 3.14 = Circumference of circle
- Diameter squared x 0.7854 = Area of circle
- Radius squared x 3.14 = Area of circle
- Miles x 1760 = yards
- Square Miles x 259 = hectares
- Square kilometers x 100 = hectares
- Acres x 40.47 = areas
- Hectares x 100 = areas
- Areas x 100 = square meters
- Yards x 3 = feet
- Acres x 4840 = square yards
Water Pressure Calculations
- Feet head (of water) x .433 = Pounds per square
inch (PSI)
- Feet head (of water) x 0.3049 = meters head (of
water)
- Feet head (of water) x 0.0295 = atmospheres
- Feet head (of water) x 2.988 = kiloPascals
- Meters head (of water) x 3.28 = feet head (of
water)
- atmosphere (Atm) x 1.013 = 1 bar (b)
- atmosphere x 14.696 = Pounds per square inch (PSI)
- bars x 1.033 = kilograms per square centimeter
- bars x 14.67 = Pounds per square inch (PSI)
- bars x 100 = kiloPascals
- Kilograms per square centimeter x 14.223 = pounds
per square inch (PSI)
- Pounds per square inch (PSI) x 2.31 = feet head
(ft. hd.)
- Pounds per square inch (PSI) x 0.0703 = kilograms
per square centimeter
- Pounds per square inch (PSI) x 0.06895 = bars
- Pounds per square inch (PSI) x 0.06805 =
atmospheres
- Pounds per square inch (PSI) x 2.31 = feet head (of
water)
- Pounds per square inch (PSI) x 6.896 = kiloPascals
- kiloPascal x 0.145 = Pounds per square inch (PSI)
- kiloPascal x 0.01 = bars
- kiloPascal x 0.334 = feet head (of water)
Flow and water Volume Formulas
- U.S. Gallons per minute (gpm) x .1337 = Cubic feet
per minute
- Cubic feet per minute x 7.48 = U.S. gallons per
minute
- Cubic feet per second x 448.8 = U.S. gallons per
minute
- U.S. gallons per minute x 0.00223 = Cubic feet per
second
- Acre inches per hour x 453 = U.S. gallons per
minute
- British Imperial gallons x 1.201 = U.S. gallons
- U.S. gallons x 0.833 = British Imperial gallons
- Acre feet x 325,850 = U.S. gallons
- Acre inches x 27154 = U.S. gallons
- Velocity in feet per second = (0.408 x GPM) /
Inside diameter of pipe in inches, squared
- Q=AV (quantity = area x velocity) ("the basic
equation of water flow")
(example: quantity in cubic feet per second = square feet
of area x feet per second velocity)
- One inch of water depth = 0.62 gallons per square
foot of area
- GPM x 226.8 = liters per hour
- cubic feet per minute x 1699 = liters per hour
- acre inches per hour x 1712.3 = liters per minute
- acre feet x 1231.7 = cubic meters
- acre inch x 102.64 = cubic meters
- velocity (feet/second) x 0.3047 = velocity
(meters/second)
- velocity (meters/second) x 3.281 = velocity
(feet/second)
Pump Calculations
The
following formulas assume 55% pump efficiency (the standard assumption).
Note:
Horsepower is Brake horse power for an electric motor. Do not use for
fuel-powered pump engines
- GPM = (horsepower x
2178) / feet head
- Feet head = (2178 x
horsepower) / GPM
- Efficiency of pump =
(GPM x feet head) /
(horsepower x 3960)
- Horse powers x 745.7 =
watts (W)
- Water flow (in cubic
meters per second) = 0.55 x
pump power (watts) / pressure (pascals)
- Water flow (in
liters per second) = 5.43 x pump
power (kilowatts) / pressure (bars)
