How Heavy Is a Gallon of Water?
a Gallon of Water weighs about
3.78 kg (8.34 lb)
Computed value (volume × density); the inputs are cited under Sources below.
- a bowling ball7.26 kg
heaviest ball allowed in tenpin bowling (16 lb); USBC sets no minimum weight
- a domestic cat4.5 kg
adult domestic cat (Felis catus); males larger; range 4.1–5.4 kg
- a gallon of water3.78 kg
1 US gallon (3.785 412 L) of pure water at 4 °C
- an iPhone 160.17 kg
iPhone 16, Apple technical specifications
- You
Open full comparison → to add more objects on one scale.
Put it in perspective
- About 1.2× a domestic cat
- About 1.9× a bowling ball
- About 22× an iPhone 16
Why weights differ
Volume is the exact US gallon definition (231 in³ = 3.785 411 784 L, printed by NIST as 3.785 412 L). Weight changes with temperature and with dissolved solids; 0.9998395 g/ml is the density at 4 °C, water's densest point.
Sources
[1] National Institute of Standards and Technology
NIST Guide to the SI, Appendix B.9: Factors for units listed by kind of quantity or field of scienceStandard body
“gallon (U.S.) (gal) liter (L) 3.785 412 E+00”
Value as published: 1 gallon (U.S.) = 3.785 412 L · accessed 2026-11-11.
[2] U.S. Geological Survey
Water DensityGovernment agency
“the exact density of water is not really 1 g/ml, but rather a bit less (very, very little less), at 0.9998395 g/ml at 4.0° Celsius”
Value as published: 0.9998395 g/ml at 4.0 °C · accessed 2026-11-11.
How this value was computed
- volume-l: 3.785412 L — 来源 [1] (source [1])
- density-kg-per-l: 0.9998395 kg/L — 来源 [2] (source [2])
Last updated 2026-11-11.Report a correction (please include a source link).
Related objects
- a gallon of milk3.9 kg (8.61 lb)
- a watermelon4.52 kg (9.96 lb)
- a 5 lb bag of flour2.268 kg (5 lb)
- a liter of water1 kg (2.2 lb)
- 5 gallons of water18.9 kg (41.7 lb)
- a loaf of bread0.567 kg (1.25 lb)
Frequently asked questions
How much does a gallon of water weigh?
a Gallon of Water weighs about 3.78 kg (8.34 lb) — 1 US gallon (3.785 412 L) of pure water at 4 °C.
How much is a gallon of water in pounds and ounces?
8.34 lb, which is 134 oz. In metric terms: 3.78 kg.
Is a gallon of water heavier than a domestic cat?
No. a Gallon of Water weighs about 3.78 kg (8.34 lb), while a domestic cat is about 4.5 kg (9.92 lb) — roughly 1/1.19.
Why do sources give different weights?
Volume is the exact US gallon definition (231 in³ = 3.785 411 784 L, printed by NIST as 3.785 412 L). Weight changes with temperature and with dissolved solids; 0.9998395 g/ml is the density at 4 °C, water's densest point.
Where does this number come from?
Every source is listed at the bottom of this page with publisher, link, access date and a verbatim quote. Numbers are only published when a qualifying source can be verified.