Wastewater Operator Calculator

The professional wastewater calculator is built for licensed operators.

16 essential calculations covering Class I through Class IV certification math — from basic Pounds formulas to MCRT, F/M Ratio, and Volatile Solids Reduction. Every result shows the formula and your substituted values so you can verify the math yourself.

CALCULATORS INCLUDED:
Hydraulics & Loading
• Pounds / Mass Loading (lb/day = MGD × mg/L × 8.34)
• Flow Rate Conversions (MGD, GPM, GPD, cfs)
• Detention Time (accepts GPD, MGD, or GPM)
• Percent Removal
• Chemical Dose / Feed Rate (dry and liquid with SG)
• Surface Overflow Rate (SOR)

Solids Control
• Sludge Volume Index (SVI)
• Return Activated Sludge Rate (RAS %)
• MLSS / MLVSS Inventory
• RAS Solids Balance

Process Control
• Sludge Age — Basic (Class I/II)
• MCRT / SRT — Full (Class III/IV, includes effluent SS)
• F/M Ratio
• Solids Loading Rate
• OUR / SOUR
• Volatile Solids Reduction (Van Kleeck)

BUILT FOR THE FIELD:
• Works 100% offline — concrete bunkers, underground pump stations, rural facilities
• Large, readable results designed for gloved hands
• "Show Your Work" expands to show your exact values substituted into the formula
• Copy Result pastes a formatted summary ready for texts or emails to your supervisor
• Formula reference screen with all formulas, variables, and source attribution
• Calculation history saves your last 20 results
• Dark mode support

SHOW YOUR WORK:
Every result displays the formula that produced it. Tap "Show Your Work" to see your actual input values plugged into the equation — the same way you'd show work on a certification exam.

Based on ABC, Sacramento State OIT, and state certification formula sheets.