Bath Salt Recipe

Relaxing Bath Salt Recipe, Measured Like a Formulator

Homemade bath salts are a dry blend of Epsom salt, sea salt, and baking soda, scented with essential oil that has first been mixed into a little carrier oil. You stir about 50 g (roughly a quarter cup) into a warm bath and soak for 15 to 20 minutes. The water feels silkier, the scent fills the room, and the oil leaves skin feeling soft afterward.

Below is a 200 g batch in grams and percentages, the reason each ingredient is there, an optional fizzy version, and honest answers about what an Epsom salt bath can and cannot do. For a wider set of bath recipes, including bubble bath, see our full guide to making your own bath salts and bubble bath.

Homemade relaxing bath salts in a jar

Ingredients (200 g, about 4 baths)

Ingredient Grams % Why it is there
Epsom salt (magnesium sulfate) 90.0 45% Dissolves quickly and gives the water a soft feel
Fine sea salt 50.0 25% Adds minerals and a classic spa texture
Baking soda (sodium bicarbonate) 49.7 24.85% Makes the water feel smooth and silky
Sweet almond oil 10.0 5% Carries the essential oil and softens skin
Anti-Age Essential Oil Blend 0.3 0.15% of the batch (3% of the carrier oil) Frankincense, neroli, and rose scent

Plant Therapy's dilution range for the Anti-Age blend is 1 to 3% in a carrier oil. Here it is used at 3% of the almond oil, the top of that range, which works out to 0.3 g, about 9 drops at the house rate, for the whole batch.

Equipment and Sanitation

  • Digital scale reading to 0.1 g
  • Large glass or stainless steel bowl and a small glass dish
  • Whisk or spatula, and a dry glass jar with an airtight lid

Wash and fully dry all tools, then wipe them with 70% isopropyl alcohol and let them air dry. Moisture is what makes bath salts clump, so the bowl, whisk, and jar must be completely dry.

Method

  1. In the small dish, stir the essential oil blend into the sweet almond oil. Never add essential oil straight to the salts or the bath water. Oil and water do not mix, so undiluted drops can float on the surface and sit on your skin at full strength.
  2. In the large bowl, whisk the Epsom salt, sea salt, and baking soda together, breaking up any lumps.
  3. Drizzle the scented oil over the salts while stirring, then rub the mix between gloved fingers until the oil is evenly spread and the salts look slightly damp.
  4. Let the blend sit uncovered for 30 minutes so the oil soaks in, then pack it into the jar and label it with the date.

To use: add 50 g (about a quarter cup) to warm running water, swirl to dissolve, and soak for 15 to 20 minutes. Pat skin dry and apply moisturizer while skin is still slightly damp. The oil can make the tub slippery, so step out carefully and rinse the tub afterward.

Optional Fizzy Version

For a gentle fizz, reduce the Epsom salt to 65 g and add 25 g citric acid. Citric acid and baking soda react only when they meet water, so the jar must stay completely dry. Humidity in a bathroom can set off the reaction early, so store the fizzy version outside the bathroom. For a stronger fizz in a molded shape, see our bath bomb recipe.

What an Epsom Salt Bath Can and Cannot Do

A warm bath with salts is relaxing, the water feels softer, and the oil leaves skin feeling moisturized. What the evidence does not support is the popular idea that you absorb meaningful magnesium through your skin in the bath. A 2017 review by Gröber and colleagues in the journal Nutrients examined the research on magnesium applied to the skin, including baths, and concluded that it could not yet recommend transdermal magnesium. The one widely quoted Epsom salt bath study, with 19 people, was published only on a commercial website and was not peer reviewed. Enjoy your bath for how it feels, not as a magnesium supplement.

Variations

  • Lavender: swap the Anti-Age blend for lavender essential oil at the same 0.3 g. Read more about lavender in skincare.
  • Unscented: leave out the essential oil and keep the almond oil for softness.
  • Extra moisturizing: raise the sweet almond oil to 16 g and reduce the sea salt to 44 g.
  • Choose your oils carefully: some essential oils are not suited to baths at all. Tisserand and Young advise avoiding lemongrass in the bath even when diluted, because it raises the risk of skin irritation.

Shelf Life and Storage

Bath salts contain no water, so they do not need a preservative. Keep water out: scoop with a dry spoon, close the lid tightly, and do not store the open jar in a steamy room. Plan to use the batch within about three months. The carrier oil slowly goes stale and the scent fades over time; discard any jar that smells off.

Safety Notes

  • Patch test the scented oil on your inner arm for 24 hours if your skin is sensitive, and for your first batch use the Anti-Age blend at the lowest rate of its range (1% of the carrier oil, 0.1 g), then work up.
  • Skip the bath salts on sunburned or broken skin.
  • If you are pregnant, have a medical condition, or take medication, ask your doctor before using essential oils or hot soaks.
  • Keep bath water warm, not hot, and limit soaks to about 20 minutes so skin does not dry out.

Troubleshooting

  • Salts clumped into a block: moisture got in. Break it up and use it soon, and store the next batch in a drier spot.
  • Oily ring on the tub: reduce the almond oil to 6 g.
  • Scent too faint: the blend is already at the supplier's top rate, so choose a stronger-smelling oil rather than adding more.
  • Fizzy salts fizzed in the jar: they were exposed to humidity. Make smaller batches and keep them sealed.

Frequently Asked Questions

How much bath salt should I use per bath?

Use about 50 g, or a quarter cup, in a standard tub. Add it under warm running water so it dissolves fully before you get in.

Do you absorb magnesium from an Epsom salt bath?

The evidence does not show meaningful magnesium absorption through skin in a bath. A 2017 review in Nutrients concluded that transdermal magnesium could not yet be recommended. A salt bath is still relaxing and leaves the water feeling soft.

Can I add essential oil directly to bath salts or bath water?

Mix it into a carrier oil first. Essential oils do not dissolve in water, so undiluted drops can float on the surface and sit on skin at full strength.

How long should I soak in a salt bath?

About 15 to 20 minutes in warm water is enough. Longer, hotter soaks can leave skin feeling dry, so moisturize afterward.

Why are my homemade bath salts clumping?

Salt pulls moisture from the air. Make sure the tools and jar are completely dry, close the lid tightly, and store the jar outside a steamy bathroom.

How long do homemade bath salts last?

Use them within about three months. They contain no water, but the carrier oil slowly goes stale and the scent fades.

Can I use table salt instead of sea salt?

Yes, plain table salt works, though many people prefer the look and texture of sea salt. Avoid salts with added anti-caking agents if you want the clearest bath water.

Shop and Learn More

Scent this recipe with our Anti-Age Essential Oil Blend, browse our bath soaks, and see the full bath salts and bubble bath guide for more recipes.

Sources

  • Gröber U, Werner T, Vormann J, Kisters K. Myth or Reality: Transdermal Magnesium? Nutrients. 2017;9(8):813. doi:10.3390/nu9080813. MDPI
  • Tisserand R, Young R. Essential Oil Safety. 2nd ed. Churchill Livingstone Elsevier; 2014 (lemongrass profile, pp. 334-335).
  • Plant Therapy, Anti-Age Essential Oil Blend product information (supplier data: dilute to 1 to 3% in a carrier).

These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.

About the Author
Written by Kari Thomas, cosmetic formulator and founder of Skin Perfection.