Leaky faucet calculator
This leaky faucet calculator turns drips per minute into wasted water. At 10 drips per minute and 1/4 milliliter per drip, a faucet wastes about 0.95 gallons a day and 347 gallons a year.
Example: Drips per minute 10 · Volume of one drip 0.25 mL · Number of leaky faucets 1 · Unit: gallons (US) → Water wasted: 0.95 gal per day, 347 gal per year. Source: USGS Water Science School, Water Q&A: Does a little leak in my house really waste water? – faucet drip between 1/5 and 1/3 mL, bathtub about 1/2 mL; 1/4 mL used: one gallon = 15,140 drips, one liter = 4,000 drips (read 10.10.2026). Updated: .
How it is calculated
Water per day = drips per minute × 1,440 minutes × volume of one drip. There is no scientific definition of a faucet drip. The U.S. Geological Survey measured kitchen and bathroom sink faucets and found 1/5 to 1/3 of a milliliter; bathtub drips are about 1/2 milliliter. For its drip calculator the USGS uses 1/4 milliliter, so one gallon is 15,140 drips and one liter is 4,000 drips.
Water wasted at 1/4 mL per drip
| Drips per minute | Gallons per day | Gallons per year |
|---|---|---|
| 1 | 0.1 | 34.7 |
| 10 | 0.95 | 347.1 |
| 60 | 5.71 | 2082.7 |
One drip per second (60 per minute) is 21.6 liters, or 5.71 gallons, a day and about 2,083 gallons a year. At 10 drips per minute the loss ranges from 0.76 to 1.27 gallons a day depending on drip size (1/5 to 1/3 mL). Enter your water and sewer price per 1,000 gallons to see the cost.
How to count
- Put a cup under the faucet and count drips for a full minute.
- For fast drips, count for 15 seconds and multiply by 4.
- For a bathtub, use about 0.5 mL per drip.
How much water sits in a pipe run is shown by the pipe volume calculator; to switch units, use the liters to gallons converter.
Frequently asked questions
How much water does a leaky faucet waste per day?
At 10 drips per minute and 1/4 mL per drip about 0.95 gallons (3.6 liters); at one drip per second about 5.7 gallons.
How many drips are in a gallon?
Using the USGS value of 1/4 mL per drip, 15,140 drips.
How much is that per year?
About 347 gallons at 10 drips per minute and about 2,083 gallons at one drip per second.
How big is a drop of water from a faucet?
The USGS says there is no scientific definition; its measurements found 1/5 to 1/3 mL at sinks and about 1/2 mL at bathtubs.
How much does a leaky faucet cost?
Enter your combined water and sewer price per 1,000 gallons; the calculator multiplies it by the water wasted.
Sources and legal basis
- USGS Water Science School, Water Q&A: Does a little leak in my house really waste water? – faucet drip between 1/5 and 1/3 mL, bathtub about 1/2 mL; 1/4 mL used: one gallon = 15,140 drips, one liter = 4,000 drips (read 10.10.2026)
- NIST SP 811, Appendix B.8: 1 gallon (U.S.) = 3.785 412 L (read 10.10.2026)
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