Operator calculator
Chlorine Dosage (mg/L) calculator
Find the dose in mg/L from a feed rate in pounds per day.
Calculator
Dose
2 mg/L
- 1. 3 MGD × 8.34 = 25.02
- 2. 50 lb/day ÷ 25.02 = 2 mg/L
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
dose (mg/L) = feed rate (lb/day) ÷ [flow (MGD) × 8.34]
| Input | Unit |
|---|---|
| Feed rate | lb/day |
| Flow | MGD |
| Result: Dose | mg/L |
Conversion factors used: 8.34 lb per gallon of water.
When to use it
Dosage questions run the pounds formula backwards: you know how much chlorine was fed and need the concentration it produced in the water.
Rearranging is the whole skill. Keep 8.34 in the denominator along with the flow.
Applies to: Water Treatment, Water Distribution.
Exam tip: If the answer is under about 0.1 mg/L or over 10 mg/L for ordinary disinfection, recheck your units.
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