Watering Can Sizes: Gallons, Weight and How to Choose

Watering Can Sizes in Gallons, Liters and Pounds

Watering can sizes are printed on the label in quarts, US gallons or liters, and the label tells you nothing about weight until you convert it. A 10 liter can, the size the Royal Horticultural Society uses as its unit when it gives watering amounts, holds 2.6 gallons. Water weighs 8.34 pounds per gallon, so a full 2 gallon can carries 16.7 pounds of water before you count the can, and a full 10 liter can carries 22 pounds.

The table converts label sizes from 1 quart to 3 gallons. Liters use the NIST factor of 3.79 liters per gallon, and the weight column is water only.

Label size	US gallons	Liters	Weight of water
1 quart	0.25	0.95	2.1 lb
Half gallon	0.5	1.9	4.2 lb
1 gallon	1	3.79	8.3 lb
5 liters	1.3	5	11 lb
1.5 gallons	1.5	5.7	12.5 lb
2 gallons	2	7.6	16.7 lb
10 liters	2.6	10	22 lb
3 gallons	3	11.4	25 lb

Weight is the number that decides whether a size works for you. Capacity only tells you how many trips to the tap you will save, and a large can that you fill halfway saves none. A gallon jug of milk or water from the kitchen makes a fair test: carry one at arm’s length from the spigot to your farthest pot, then imagine two.

Watering Can Dimensions

Dimensions vary by design, but the body has a floor set by volume. One US gallon is about 231 cubic inches. A 1 gallon can therefore needs a body at least the size of a cylinder 7 inches across and 6 inches tall. A 2 gallon can needs 462 cubic inches, which is a cylinder 8 inches across and a little over 9 inches tall. A 10 liter can needs about 610 cubic inches, or 9 inches across and nearly 10 inches tall. A half gallon indoor can fits in a cylinder 5 inches across and 6 inches tall.

Real cans are taller than those figures because they need headroom so the water does not slosh out, and the spout and handle add most of the overall length. Before you buy, measure two things at home: the clearance under the tap you will fill from, and the gap between any shelves you need to reach between. Then compare both with the height and length printed on the listing.

The spout matters for carrying as well as pouring. If the spout’s opening sits lower than the rim, water runs out of it before the can is full, so the usable capacity is smaller than the label says.

Which Size to Choose

Start from what you water, then check that you can lift the answer.

For houseplants, 1 quart to half a gallon keeps the filled weight to between 2.1 and 4.2 pounds, light enough to hold at arm’s length over a shelf. A long, narrow spout lets you put water on the soil under the leaves. If your plants prefer water from below, bottom watering houseplants needs no can at all.

For a patio or balcony of pots, 1 to 1.5 gallons is a workable range, at 8.3 to 12.5 pounds of water. University of Maryland Extension says each watering should re-moisten the entire container until excess water drips from the drain holes, and that a large container may need several gallons. NC State’s handbook adds that most containers need water at least once a day when plants are mature. A handful of big pots can therefore mean several trips even with a 2 gallon can. How often to water container plants in summer covers the schedule.

For beds, borders and new plantings, 2 gallons or 10 liters cuts the walking. The Royal Horticultural Society’s guide figure for a newly planted tree is four to six full 10 liter cans per week in dry weather, which is 88 to 132 pounds of water carried each week for one tree. At that point a hose is the reasonable tool. The same guidance recommends a hose when lifting and carrying cans is difficult or when the area is large.

If a full 2 gallon can is too heavy, two 1 gallon cans, one in each hand, carry the same 16.7 pounds with the load balanced.

Spout and Rose: How the Water Lands

The rose is the perforated cap on the end of the spout. With the rose off, the can pours a single stream that you can aim at the base of a plant. The Royal Horticultural Society favors this because it keeps the surrounding soil drier, which reduces weed growth and puts the water at the roots. University of Maryland Extension gives the same advice for containers: apply water to the potting mix at the base of the plant and keep it off the leaves, since wet leaves can spread disease.

With the rose on, the stream breaks into a gentle, rain-like flow. That is what freshly sown seed and new transplants need. University of Maryland Extension says to water gently after seeding or transplanting so the seeds or transplants do not shift, tip over, or have their roots exposed. Choose a can with a removable rose so that one can does both jobs. On a long-spout indoor can a rose is rarely needed.

Metal or Plastic, and Other Details

The Royal Horticultural Society rates metal cans as the most durable and environmentally friendly option. Whatever the material, check the empty weight on the listing, because it is added to the 16.7 to 22 pounds of water at the larger sizes.

Two handles help with a full can. A top handle carries the weight on the way out, and a rear handle lets you tip the can without twisting your wrist. An opening wide enough for your hand makes the inside easy to scrub.

A can also pairs well with stored rainwater. It fits easily under the tap of a rain barrel, which makes stored rainwater simple to use, and choosing a rain barrel for garden watering explains how to set one up. For how much to carry and when, see the summer watering schedule.