Calculator 01
Flow conversion
Convert between gallons per minute, million gallons per day, and cubic feet per second.
Converted flow
1.44
MGD
1,000 GPM ÷ 694.444 = 1.44 MGD
Free operator math workspace
Calculate it. Check the units. See the work.
Six practical calculators for water treatment, distribution, and wastewater operations. Results stay in your browser; nothing is submitted or stored.
Training tool, not a process-control order. Verify plant-specific units, chemical product data, calibration, and standard operating procedures before changing an operating setpoint.
1 MGD = 694.444 GPM
Calculator 02
Tank volume
Calculate gallons in rectangular or circular tanks using inside dimensions.
Tank volume
71,813
gallons
40 ft × 20 ft × 12 ft × 7.48052 gal/ft³
Calculator 03
Detention time
Estimate theoretical time in a tank from liquid volume and flow.
Theoretical detention time
4.17
hours
250,000 ÷ 1,000 ÷ 60
Calculator 04
Pounds per day
Convert flow and concentration to a daily mass loading.
Mass loading
250.2
lb/day
2.0 × 15 × 8.34
Calculator 05
Liquid chemical feed
Estimate gallons per day of a liquid solution from flow, target dose, strength, and specific gravity.
Estimated solution feed
40.0
gal/day
50.04 lb/day ÷ (0.125 × 1.2 × 8.34)
Calculator 06
Sludge Volume Index (SVI)
Wastewater activated-sludge settling indicator using 30-minute settled volume and MLSS.
Sludge Volume Index
80.0
mL/g
240 × 1,000 ÷ 3,000
Unit reference
Formulas worth memorizing
The calculator shows the work, but operators still need to recognize the unit pattern and know when a result is unreasonable.
Daily mass
MGD × mg/L × 8.34 = lb/day
Use when flow is in million gallons per day and concentration is in milligrams per liter.
Detention time
gallons ÷ GPM ÷ 60 = hours
Use liquid volume, not total structural volume above the water surface.
Rectangular tank
L × W × depth × 7.48052 = gallons
All dimensions must be feet.
Circular tank
π × (D ÷ 2)² × depth × 7.48052
Use inside diameter and actual water depth.