What units does this calculator support?

Volume: US gallons, liters, cubic feet, and cubic meters. Flow rate: GPM (gallons per minute), GPH (gallons per hour), LPM (liters per minute), LPH (liters per hour), and CFM (cubic feet per minute). All combinations work — the calculator converts internally.

What does the drain rate field do?

If water is leaving the tank at the same time (for example, a leak or an outlet), enter that drain rate. The calculator subtracts it from the fill rate to give the net fill time. If drain equals or exceeds fill, the tank never fills.

How accurate is the calculation?

The result is exact given steady flow rates. Real-world fill times vary because flow rates drop as backpressure increases (e.g., garden hose filling a pool). Use the calculator as a baseline estimate.

Can I use this for partial fills?

Enter only the remaining capacity needed. For example, if a 500-gallon tank is already 200 gallons full, enter 300 gallons as the capacity.

Tank Fill Time Calculator

Name: Tank Fill Time Calculator
Availability: InStock
Author: Nham Vu

Enter tank capacity and fill flow rate to get the exact fill time in hours, minutes, and seconds.

Tank & Flow Inputs

Tank Capacity

Fill Flow Rate

GPM = gallons/min · GPH = gallons/hr · LPM = liters/min · LPH = liters/hr · CFM = cubic ft/min

Drain / Outlet Rate (optional)

100%

Enter tank capacity and fill rate

Common Flow Rates

Garden hose: ~9 GPM

Kitchen faucet: ~2 GPM

Pool pump: 30–60 GPM

Fire hydrant: 500–1000 GPM

Well pump (residential): 5–15 GPM

Submersible pump: 10–25 GPM

Summary

Enter tank capacity and fill flow rate to get the exact fill time in hours, minutes, and seconds.

How it works

Enter your tank capacity and select the volume unit (gallons, liters, cubic feet, or cubic meters).
Enter the fill flow rate and select the rate unit (GPM, GPH, LPM, LPH, or CFM).
Optionally enter a simultaneous drain rate in the same units to compute net fill time.
The fill time updates instantly — results show hours, minutes, and seconds.
Watch the animated water-level bar rise as you adjust your inputs.

Use cases

Estimate how long a swimming pool will take to fill with a garden hose or pump.
Plan water storage tank refills at farms, campsites, or remote properties.
Check if a sump pump can keep up with inflow during heavy rain.
Calculate fill times for industrial tanks, aquariums, or rainwater harvesting barrels.

Frequently Asked Questions

Last updated: 2026-06-15 · Reviewed by Nham Vu