Epsom Salt USP Grade (Magnesium Sulfate) — Bath, Foot Soak & Garden

For a standard 40-gallon bathtub, use 2 cups (about 400 g) of Epsom salt. Add it while the water is running for best dissolution. For a larger garden tub (60+ gallons), use 3 cups. For a lighter soak, 1.5 cups works well. For a sitz bath, use 1 cup per 6 inches of water depth. Use the calculator in the directions section above to dial in any other volume.

Many people enjoy Epsom salt soaks two to three times per week as part of an evening wind-down routine. There's no strict frequency limit for healthy adults using it externally. If you have any medical conditions, take medications, or are pregnant or nursing, check with your healthcare provider for personalized guidance.

Yes. Our magnesium sulfate is sourced from within the United States and packaged at our family-owned Madera, California facility — registered with the FDA. Every batch is third-party lab tested for purity and screened for heavy metals before it ships.

USP Grade means our Epsom salt meets the purity, identity, and contaminant-limit standards set by the United States Pharmacopeia for magnesium sulfate. It's the same specification used for pharmaceutical excipients. Hardware-store and garden-grade magnesium sulfate isn't tested to this specification — fine for de-icing, not what you want dissolving in your bath. USP Grade is a purity standard, not a use designation: it doesn't make a product automatically suitable for oral use.

No. Magnesium sulfate is a stable mineral compound with an indefinite shelf life. Store it in a cool, dry place in the resealable bag or another airtight container to prevent moisture absorption and clumping. It won't lose effectiveness over time even after years in storage.

Different compounds entirely. Epsom salt is magnesium sulfate (MgSO₄·7H₂O); table salt is sodium chloride (NaCl). Epsom contains magnesium and sulfur; table salt contains sodium and chlorine. The "salt" in both names refers to the crystal structure — a positively charged ion paired with a negatively charged one — not to the seasoning you put on food. They cannot be substituted for each other in any use case.

Yes — this is a popular way to customize the bath experience and one of the reasons we keep our Epsom salt fragrance-free. Add the oil after you've stepped into the tub (not while water is running) so the aroma rises with the steam rather than evaporating early. Popular pairings: Lavender (10-15 drops, calming), Eucalyptus (8-12 drops, spa-style steam), and Peppermint (5-8 drops, cooling).

No. Our fine-grain Epsom salt dissolves completely in bath water and is safe for standard plumbing and septic systems when used as directed. Magnesium sulfate is biodegradable and environmentally benign at normal bath-use concentrations — much lower environmental impact than fragranced or dyed bath products.

Yes, when used appropriately. Epsom salt supplies magnesium and sulfur — two plant nutrients — and is one of the fastest, most affordable corrections for genuine magnesium deficiency (visible as yellowing between leaf veins, with veins staying green). Apply only when deficiency is confirmed or suspected. Healthy plants in balanced soil don't benefit from added magnesium; excess can interfere with calcium uptake. See the garden tab in the How-to-Use section, the tree-stump removal guide, or the full garden boost guide for more.

Our USP Grade Epsom salt is pure magnesium sulfate with no added fragrances, dyes, or preservatives — a cleaner option for sensitive skin than scented bath products. If you're new to Epsom soaks, start with a smaller amount (1 cup instead of 2) and a shorter soak time (15 minutes instead of 30) to see how your skin responds. Discontinue immediately if irritation occurs.

This product is labeled and sold for external use only — bath soaks, foot soaks, body scrubs, and garden applications. It does not carry dietary-supplement labeling, so we don't provide oral-use directions. Our Magnesium Chloride USP is the Greenway magnesium product approved for oral use, subject to its current labeling. For ingestion-based use cases, talk to a healthcare provider.

Magnesium sulfate heptahydrate has the formula MgSO₄·7H₂O and a molecular weight of 246.47 g/mol. Magnesium itself is 24.305 g/mol. So 24.305 ÷ 246.47 = ~9.86% elemental magnesium by weight. Per pound of Epsom salt (453.6 g), that's roughly 44.7 g of elemental magnesium and ~59 g of elemental sulfur (the other ~13%). The remainder is oxygen and the seven water molecules locked into the crystal.