Gallons to Pounds Converter
Convert gallons of water to pounds, or pounds to gallons, and do the same for any liquid by entering its specific gravity.
Results
| Item | Value |
|---|
Quick Answer
A US gallon of water weighs about 8.34 pounds, so multiply gallons by 8.34 to get pounds: 5 gallons of water is 41.7 lb, 55 gallons is 458.7 lb and 100 gallons is 834 lb. To turn pounds of water into gallons, divide by 8.34. For other liquids, multiply 8.34 by the liquid’s specific gravity first.
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Table of Contents
- Gallons to Pounds Converter
- Quick Answer
- Related Calculators
- How This Gallons to Pounds Converter Works
- How to Use the Gallons to Pounds Converter
- Gallons to Pounds Formulas
- Key Terms
- Worked Example
- Real-Life Examples
- Gallons vs Pounds
- Gallons of Water to Pounds Chart
- Why the Weight Changes With the Liquid
- Common Mistakes to Avoid
- Frequently Asked Questions
- References & Sources
How This Gallons to Pounds Converter Works
Gallons measure volume and pounds measure weight, so to convert between them you need to know how heavy the liquid is. For water the answer is about 8.34 pounds per US gallon. Choose the direction, pick water or enter another liquid’s specific gravity, enter the amount and press Calculate. The converter gives pounds (or gallons), the pounds per gallon it used, and the kilograms, liters and tons.
Quick explanation: 1 gallon of water ≈ 8.34 lb.
- gal to lb (water): multiply by 8.34.
- lb to gal (water): divide by 8.34.
- Other liquids: use 8.34 × specific gravity.
How to Use the Gallons to Pounds Converter
- Choose gallons to pounds or pounds to gallons.
- Choose water, or another liquid and enter its specific gravity.
- Enter the amount.
- Press Calculate.
- Read the weight or volume, plus kilograms, liters and tons.
Gallons to Pounds Formulas
- Water: pounds = gallons × 8.34
- Any liquid: pounds = gallons × 8.34 × specific gravity
- Gallons from pounds: gallons = pounds ÷ (8.34 × specific gravity)
- Specific gravity: the liquid’s density divided by water’s density
- Metric check: 1 gal = 3.785 L, and 1 L of water is about 1 kg
Key Terms
- US gallon: 231 cubic inches, 3.785 L.
- Specific gravity: a liquid’s density compared with water’s.
- Density: mass per unit of volume.
- Pound (lb): 0.45359237 kg.
- Imperial gallon: the UK gallon, 4.546 L; water weighs about 10 lb per imperial gallon.
Worked Example
How much does a 55 gallon drum of water weigh, and what if it held a liquid with a specific gravity of 1.2?
- Water: 55 × 8.34 = 458.7 lb, or 208 kg
- Liquid with SG 1.2: 8.34 × 1.2 = 10.008 lb/gal, and 55 × 10.008 = 550.4 lb
- Add the drum itself to get the total shipping weight.
Going the other way, 1,000 lb of water is 1,000 ÷ 8.34 = 119.9 gallons.
Real-Life Examples
- Water jugs: a 5 gallon jug holds 41.7 lb of water.
- Hot tubs: 400 gallons of water weighs 3,336 lb.
- Trailers: a 100 gallon tank adds 834 lb.
- Aquariums: a 75 gallon tank holds 626 lb of water.
Gallons vs Pounds
- Gallon: a volume, 231 cubic inches or 3.785 L.
- Pound: a weight, 0.4536 kg.
- Link: the liquid’s density; for water, 8.34 lb fills one gallon.
Gallons of Water to Pounds Chart
Water at 8.34 lb per US gallon (USGS).
| Gallons | Pounds | Kilograms |
|---|---|---|
| 0.5 gal | 4.17 lb | 1.89 kg |
| 1 gal | 8.34 lb | 3.78 kg |
| 2 gal | 16.68 lb | 7.57 kg |
| 3 gal | 25.02 lb | 11.35 kg |
| 5 gal | 41.70 lb | 18.91 kg |
| 10 gal | 83.40 lb | 37.83 kg |
| 15 gal | 125.10 lb | 56.74 kg |
| 20 gal | 166.80 lb | 75.66 kg |
| 25 gal | 208.50 lb | 94.57 kg |
| 50 gal | 417.00 lb | 189.15 kg |
| 55 gal | 458.70 lb | 208.06 kg |
| 100 gal | 834.00 lb | 378.30 kg |
| 250 gal | 2,085.00 lb | 945.74 kg |
| 500 gal | 4,170.00 lb | 1,891.48 kg |
| 1000 gal | 8,340.00 lb | 3,782.96 kg |
Why the Weight Changes With the Liquid
A gallon is always the same volume, 231 cubic inches, but different liquids pack different amounts of mass into it. Specific gravity compares a liquid with water: a liquid with a specific gravity of 0.8 weighs 80% as much as the same volume of water, and one of 1.3 weighs 30% more. Oils and fuels are usually lighter than water and float on it; salt water, syrups, antifreeze mixes and many chemicals are heavier. Safety data sheets list specific gravity or relative density for most products.
Even water varies a little. It is densest at about 4 °C (39 °F) and slightly lighter when warm, so a gallon of hot water weighs a few hundredths of a pound less. Salt water from the ocean is about 3% heavier. For shipping, tank loads, truck limits and floor loading, 8.34 lb per gallon is the standard figure; for laboratory work, use the density at the actual temperature.
Common Mistakes to Avoid
- Using 8.34 for every liquid. Multiply by the specific gravity.
- Mixing US and UK gallons. A UK gallon of water is about 10 lb.
- Forgetting the container. Drums and tanks add weight.
- Confusing weight and volume. A gallon is not a fixed weight.
- Using hot water figures for cold tanks. The difference is small but real.
Frequently Asked Questions
About 8.34 pounds per US gallon.
Multiply gallons by 8.34 for water, or by 8.34 × specific gravity for other liquids.
5 gallons of water weighs about 41.7 lb.
About 458.7 lb.
100 lb of water is 11.99 gallons.
Slightly; milk is a little denser than water.
A liquid’s density divided by water’s density.
About 8,340 lb, or 4.17 short tons.
About 10 lb, since an imperial gallon is 4.546 L.
References & Sources
| Source | Used For | Link |
|---|---|---|
| USGS Water Science School, A Million Gallons of Water | At 8.34 pounds per gallon, a million gallons weighs 8,340,000 pounds. | https://www.usgs.gov/water-science-school/science/a-million-gallons-water-how-much-it |
| NIST, Guide to the SI, Appendix B.8 | US gallon = 3.785412 L; pound = 0.4535924 kg. | https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8 |