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Tank Volume & Retention Time Calculator

Work out a tank’s volume and hydraulic retention time (HRT) — for rectangular or cylindrical tanks — from its dimensions and the flow through it. Useful for sizing balance, contact, reaction and storage tanks.

Tank & flow

Result

Liquid volume (m³)
Volume (litres)
HRT (hours)
HRT (minutes)
HRT = liquid volume ÷ flow. Volume is the working (liquid) volume at the depth entered — add freeboard separately for the physical tank height. Typical HRTs: rapid mix ~0.5–2 min, flocculation ~15–30 min, equalisation hours, anaerobic digestion days.