Flow conversion
1 MGD ≈ 694.444 gpm · 1 cfs ≈ 448.831 gpm
Formula · units · worked result
Set up operator math before touching the calculator.
Use the calculators to verify a setup, then generate fresh drills until the units and formula choice become automatic.
The rule that prevents most mistakesWrite units on every value → convert to compatible units → select the formula → estimate the magnitude → calculate → label the answer.
Tank volume
Rectangular: L × W × depth · Circular: π × radius² × depth · 7.48052 gal/ft³
Detention time
Time (min) = volume (gal) ÷ flow (gpm)
Pounds per day
lb/day = MGD × mg/L × 8.34
Liquid product feed
First find active lb/day, then divide by product strength as a decimal.
Sludge Volume Index
SVI (mL/g) = settled sludge (mL/L) ÷ MLSS (g/L)
Operational boundary: A calculator does not replace a facility SOP, calibrated instrument, approved dose-control method, or supervisor review.