Operator calculator
Pounds Formula (lb/day) calculator
Convert a flow and a concentration in mg/L into pounds per day.
Calculator
Load
62.55 lb/day
- 1. 2.5 MGD × 3 mg/L × 8.34 = 62.55 lb/day
For instructional use. Results assume the standard conversion factors shown on this page. Actual field calculations may need chemical strength, density, temperature, and other adjustments, so check your plant’s procedures.
Formula and inputs
lb/day = flow (MGD) × concentration (mg/L) × 8.34 lb/gal
| Input | Unit |
|---|---|
| Flow | MGD |
| Concentration | mg/L |
| Result: Load | lb/day |
Conversion factors used: 8.34 lb per gallon of water.
When to use it
The pounds formula is the workhorse of operator math. It turns a flow in million gallons per day and a concentration in milligrams per liter into the weight of chemical or solids moved each day.
Chemical feed, solids loading, and BOD loading all start here, so most other formulas on this page cluster are variations of it.
Applies to: Water Treatment, Water Distribution, Wastewater Treatment.
Exam tip: Write MGD and mg/L next to each number before you multiply. If a flow is in gpm, convert to MGD first.
Study guides
Build the math skill behind the calculator
Water Operator Math Made Simple walks through the formulas step by step.
Water Operator Math Made Simple
A Step-by-Step Guide to the Math Every Water Operator Needs to Know