LifeTally
Tank fill time calculator
How long until my tank contains at least my target volume?
Use your current volume, target volume and constant inlet and outlet rates to estimate remaining fill time.
Your volumes and constant flows
Enter litres and litres per minute. Use your own total flows, held constant until the target; enter 0 for no flow. All four values may be zero or fractional.
How the estimate works
Subtract the current volume from the target and use zero if the target is already met. Subtract outlet flow from inlet flow. For a positive remaining volume and positive net inlet, divide the remaining litres by net litres per minute. If the net inlet is not positive, a higher target is unreachable under these constant flows.
R = max(Vtarget − Vnow, 0)
q = Qin − Qout
R = 0: t = 0
R > 0, q > 0: t = R ÷ q
R > 0, q ≤ 0: —A constant liquid-volume balance using only the entered flows. Choose a target that fits your actual vessel; capacity, geometry and overflow are not checked. Pressure changes, pump curves, automatic shutoff, evaporation, reactions and other volume changes are not modeled. This does not calculate emptying time, water quality or suitability, and does not guarantee the actual completion time.
OpenStax: volume flow rate and volume per time ↗Check the filled example
Chosen example: 100 L now, target 500 L, inlet 12 L/min and outlet 2 L/min. The remaining volume is 400 L, the net inlet is 10 L/min, and the model time is 40 min. These are chosen example inputs, not recommended flows or tank dimensions.
Accepted input values
- Current volume, L
- 100
- Target volume: at least this much, L
- 500
- Total inlet flow, L/min
- 12
- Total outlet flow, L/min
- 2