Bath Salt Ratio Chart: How Much Salt Per Bath (Printable)

Two cups of Epsom salt in a standard 40-gallon tub is the ratio worth memorising, and one cup of Dead Sea salt does the same job because the grain is heavier. That works out to roughly 3.3 grams of salt per litre of bathwater.

The chart below gives all five salts at three tub sizes at once, in cups, grams or ounces, and tells you how many baths come out of the jar you are filling. Print it and stick it inside the bathroom cupboard.

Last updated 2026-10-31.

How many baths a jar of bath salts holds

This is the number almost every bath salt recipe leaves out, and it is the one people actually want. A recipe gives you batch quantities — two cups of Epsom, one of soda, fifteen drops of oil — and then stops, so you are left holding a full pint jar with no idea whether it is one bath or six.

The arithmetic is simple once you have both halves. A 16-ounce pint jar holds two cups, which is exactly one standard-strength Epsom bath. A quart jar is four cups, so two baths. An 8-ounce jar is one cup — half a bath at full strength, or one light everyday soak. Switch the jar control above and the last column rewrites itself for every salt, which matters because a pint of Dead Sea salt is two baths rather than one.

If you are making these as presents, that number belongs on the label: a jar that says "the whole jar, under the running tap" gets used properly, and one that says nothing gets a sprinkle. The homemade bath salts gift jar covers the packaging side, and if the jar is going into a larger present, bath gift basket ideas and bath gifts for men cover what else goes in the box.

Why Dead Sea salt is half the Epsom dose

Not because it is stronger medicine — because a cup of it weighs more and dissolves into a saltier bath. Dead Sea salt runs about 0.6 lb per cup against Epsom's 0.55 lb, in coarser grains that are mostly magnesium and potassium chloride rather than magnesium sulfate, and a full two cups makes water that feels briny rather than soft. One cup lands in the same place Epsom's two do. Magnesium chloride flakes sit in between at a cup and a half, and baking soda is not a salt at all, which is why half a cup is the whole dose. The longer comparison is in Epsom salt vs. Dead Sea salt.

Reading the chart in grams and ounces

Switch the units if you measure by weight, and note that the chart is deliberately quantised to quarter-cup steps — that is the resolution a measuring cup actually has, and the gram figures are converted from those steps rather than the other way round. Two cups of Epsom salt is 499 g, call it half a kilo; a cup is about 250 g. Ounces here are ounces by weight, not fluid ounces, while jar sizes are the fluid-ounce figures printed on canning jars. That mismatch is the one genuine trap on this page: a 16-ounce jar holds two cups, but two cups of Epsom salt weighs about 17.6 ounces.

Printing the chart, and putting it on your own site

The print button sends only the chart to the printer — not the navigation, the controls or this write-up — with the settings you chose stamped along the top, so a printed sheet says which unit and strength it was generated at. Print one at standard strength in cups for the cupboard, and one in grams if you keep a scale in the bathroom.

The chart is free to reuse. Copy the embed line above, or simply retype the numbers into your own post — the ratios are not ours to own, and a reader who gets the right amount from your page rather than this one is still a reader who got the right amount. If you want the interactive version instead, the bath salt calculator answers for one tub at a time and gives a cost per soak with it.

The limits of a ratio chart

A chart cannot see your tub. The gallon figures above are the usual ones — 25 for a small or half-filled tub, 40 for a standard, 60 for a deep soaker — but a shallow fill in a big tub is a small tub, and the only real measure is how much water is covering you. Round down on the first bath and up on the second.

It also makes no medical claim. The right amount of Epsom salt makes the water feel softer and the soak feel deliberate; it does not detox anything, and the evidence for magnesium crossing intact skin is thin. If you are pregnant, have a heart condition or have broken skin, ask a doctor before changing what goes in the bath, and if your skin runs dry use the light column and read the dry-skin soak first. One thing on this chart needs no measuring at all: a bath bomb is pre-dosed at one per tub, and if you would rather make your own, a bath bomb kit supplies the moulds.

The reasoning behind the two-cup figure, rather than the numbers themselves: how much bath salt to use per bath. How long to stay in once it is poured: the bath soak timer.

Mami says: A pint jar is one bath. Tip the whole thing in and stop rationing it.