Quick answer: how much does 500 gallons of water weigh?
This is the common everyday answer using about 8.34 pounds per US gallon.
Water alone is already more than two US tons before adding a tank, trailer, or frame.
An imperial gallon is larger than a US liquid gallon, so the total weight is higher.
Saltwater is denser than freshwater, so the same volume weighs slightly more.
Simple formula: pounds ≈ gallons × 8.34
For 500 US gallons: 500 × 8.34 ≈ 4,170 lb.
Gallons of water to pounds table
Use this table for quick tank, trailer, pool, or storage estimates. Values are rounded for everyday planning.
| US gallons | Approx. pounds | Approx. kilograms | Use case |
|---|---|---|---|
| 50 gallons | 417 lb | 189 kg | Small tank / barrel |
| 100 gallons | 834 lb | 379 kg | Storage tank / aquarium system |
| 250 gallons | 2,085 lb | 946 kg | Large tank / small trailer |
| 500 gallons | 4,170 lb | 1,891 kg | Water tank / trailer / pool load |
| 750 gallons | 6,255 lb | 2,837 kg | Large storage load |
| 1,000 gallons | 8,340 lb | 3,783 kg | Large tank / pool / water delivery |
When 500 gallons matters
500-gallon water tank
A 500-gallon tank contains more than two tons of water when full. The empty tank, fittings, frame, pump, and support base must be added separately when estimating total load.
Water trailer or hauling load
For a trailer, water weight is only one part of the total towing load. Add the trailer, tank, axle, frame, pump, hose, and any cargo. Check vehicle and trailer ratings before hauling.
Pool or large container
500 gallons is a small pool volume compared with many backyard pools, but it still weighs thousands of pounds. For elevated decks, balconies, indoor rooms, or temporary structures, do not rely on a simple web calculator for structural approval.
Saltwater and mixed water
Saltwater is heavier than freshwater. This page uses a simple saltwater estimate for planning. Exact values vary by salinity and temperature.
Related water weight calculators
500 gallons water weight FAQ
How much does 500 gallons of water weigh in pounds?
500 US gallons of freshwater weighs about 4,170 pounds. This is a practical estimate using about 8.34 pounds per US gallon.
How much does 500 gallons of water weigh in kilograms?
500 US gallons of water weighs about 1,890 kilograms. Exact values vary slightly with temperature and water composition.
How many tons is 500 gallons of water?
500 US gallons of water is about 2.09 US tons. This is water only and does not include the tank, trailer, or container.
Does a 500-gallon tank weigh only 4,170 pounds?
No. 4,170 pounds is the approximate weight of the water only. A full tank weighs the water plus the empty tank, fittings, frame, base, pump, and other equipment.
Is imperial gallon weight different?
Yes. An imperial gallon is larger than a US liquid gallon, so 500 imperial gallons of water weighs about 5,000 pounds.