How to Make Bath Bombs: Recipes, Ingredients, and Packaging Ideas

How Bath Bombs Actually Work

The fizzing reaction is an acid-base chemical reaction between sodium bicarbonate (baking soda, pH 8.3) and citric acid (pH 2.2). In their dry state, these two powders coexist without reacting. When they contact water, the citric acid dissolves and donates hydrogen ions (H+) to the baking soda, which releases carbon dioxide gas (CO2). The CO2 bubbles create the fizzing effect. The reaction is: NaHCO3 + C6H8O7 (arrow) Na3C6H5O7 + 3CO2 + 3H2O.

The ratio of baking soda to citric acid determines the intensity and duration of the fizz. A 2:1 ratio (two parts baking soda to one part citric acid by weight) produces a moderate fizz that lasts 60 to 90 seconds. A 2.5:1 ratio produces a slower, gentler fizz lasting 90 to 120 seconds. Ratios above 3:1 leave unreacted baking soda, which makes the bath water feel slippery and alkaline. Ratios below 2:1 leave unreacted citric acid, which can irritate sensitive skin. All three recipes below use a 2:1 ratio, which is the standard for commercial bath bombs.

Epsom salt (magnesium sulfate) does not participate in the fizzing reaction. It dissolves in bathwater and is absorbed through the skin, where magnesium acts as a muscle relaxant. The clinical evidence for transdermal magnesium absorption is mixed, but Epsom salt baths are widely recommended by physical therapists for post-workout recovery and by dermatologists for eczema and psoriasis relief. A standard bath bomb contains 1 to 2 tablespoons of Epsom salt, delivering approximately 2 to 4 grams of magnesium sulfate to the bathwater.

Ingredient Sourcing Guide

Every ingredient listed below is available on Amazon or at a local craft store (Michaels, Hobby Lobby, or Joann). Buy in bulk to reduce the per-bomb cost. The prices listed are current as of May 2026 based on Amazon pricing.

Dry Ingredients

• Sodium bicarbonate (baking soda): Arm & Hammer baking soda, 13.5 lb bag, $12 on Amazon. This yields approximately 120 bath bombs at $0.10 per bomb. Do not use baking powder, which contains cornstarch and aluminum compounds that affect the fizz.
• Citric acid: Pure citric acid powder, 2 lb bag, $14 on Amazon. This yields approximately 80 bath bombs at $0.18 per bomb. Ensure the product is 100% citric acid, not a citric acid blend with added salt or sugar.
• Epsom salt: Dr. Teal's Pure Epsom Salt, 6 lb bag, $8 at Walmart. This yields approximately 60 bath bombs at $0.13 per bomb. Use fine-grain Epsom salt for smooth texture; coarse grain leaves gritty particles in the bath bomb.
• Cornstarch (optional): Argo cornstarch, 16 oz box, $2.50 at any grocery store. Cornstarch slows the fizzing reaction, extending it by 20 to 30 seconds. It also makes the bath bomb harder and less crumbly. Substitute arrowroot powder ($6 for 8 oz on Amazon) if you prefer a gluten-free option.

Wet Ingredients

• Carrier oil: Sweet almond oil, 16 oz bottle, $9 on Amazon. This yields approximately 50 bath bombs at $0.18 per bomb. Alternatives include fractionated coconut oil ($11 for 16 oz), jojoba oil ($14 for 16 oz), or avocado oil ($8 for 16 oz). Sweet almond oil absorbs into skin without leaving a greasy residue, which makes it the best all-purpose choice.
• Witch hazel: Thayers Alcohol-Free Witch Hazel, 12 oz bottle, $7 at Target. Witch hazel is the binding liquid that activates just enough of the acid-base reaction to make the mixture clump together without triggering full fizzing. Water works too, but witch hazel gives you a longer working time (3 to 4 minutes versus 60 to 90 seconds with water) because it contains less water by volume.
• Fragrance oil or essential oil: Fragrance oils cost $6 to $10 per 4 oz bottle on Amazon and are formulated specifically for bath products. Essential oils cost $8 to $25 per 0.5 oz bottle depending on the variety. For beginners, fragrance oils are more reliable because they are pre-formulated for skin contact and produce consistent scent strength. Use 0.5 to 1 teaspoon (2.5 to 5 ml) of fragrance oil per batch of 8 bath bombs.

Colorants

• Soap colorant (mica powder): $8 to $12 for a set of 12 colors on Amazon. Mica powder is skin-safe, does not stain bathtubs, and produces vivid colors at 1/8 to 1/4 teaspoon per batch. Do not use food coloring, candle dye, or craft pigment, none of which are formulated for skin contact and can stain porcelain.
• Botanical additives (optional): Dried lavender buds ($8 for 4 oz), rose petals ($10 for 4 oz), or calendula petals ($9 for 2 oz). Add 1 tablespoon per batch for visual appeal. Avoid fresh flowers, which introduce moisture and cause premature fizzing.

Recipe 1: Classic Lavender Bath Bomb

This is the simplest recipe and the best starting point if you have never made bath bombs before. It produces a firm, round bomb with a gentle lavender scent and a pale purple color. Yield: 8 bath bombs using 2.25-inch spherical molds.

Dry Ingredients

• 1 cup (224 g) baking soda
• 1/2 cup (112 g) citric acid
• 1/2 cup (112 g) Epsom salt
• 1/2 cup (60 g) cornstarch

Wet Ingredients

• 2 tablespoons (30 ml) sweet almond oil
• 1 teaspoon (5 ml) lavender essential oil (doTERRA or Now Foods, $12 for 15 ml)
• 1/4 teaspoon purple mica powder
• Witch hazel in a spray bottle (approximately 2 to 3 tablespoons needed)

Mixing Instructions

Sift all dry ingredients through a fine-mesh strainer into a large glass or stainless steel bowl. Sifting removes clumps in the baking soda and citric acid, which cause weak spots in the finished bomb. Whisk the dry ingredients together for 60 seconds to distribute them evenly.

In a separate small bowl, combine the sweet almond oil, lavender essential oil, and purple mica powder. Stir until the mica is fully dissolved in the oil (there should be no visible specks). Pour this oil mixture over the dry ingredients. Use your fingers (wear nitrile gloves) to rub the oil into the dry mixture until it resembles damp sand. The texture should hold together when you squeeze a handful, but break apart when you press it with your thumb.

Spray witch hazel over the mixture one pump at a time, mixing after each spray. After 8 to 12 sprays, test the consistency by squeezing a handful firmly. If it holds its shape when you release pressure, the mixture is ready. If it crumbles, add 2 more sprays and test again. Stop immediately when the mixture holds its shape. Over-wetting is the most common mistake and causes the bombs to activate (fizz) in the mold instead of in the bathtub.

Molding and Curing Techniques

Pack the mixture into both halves of a 2.25-inch spherical mold (available on Amazon in a set of 3 pairs for $8). Overfill each half slightly, then press the two halves together firmly. You should feel and hear the mixture compress. Hold the mold together for 10 seconds, then gently tap the outside of the mold with the back of a spoon. Open the mold and remove the bomb. If the bomb crumbles, the mixture was too dry; add 2 more sprays of witch hazel to the remaining mixture and try again. If the bomb sticks in the mold, the mixture was too wet; add 1 tablespoon of dry mixture (equal parts baking soda and citric acid) to the remaining batch.

Drying Time

Place the molded bombs on a sheet of parchment paper or a silicone baking mat. Let them dry at room temperature (65 to 75 degrees Fahrenheit, below 50% humidity) for at least 4 hours. In humid climates (above 60% relative humidity), extend drying time to 8 to 12 hours. Do not use a hair dryer or oven to speed drying; heat activates the acid-base reaction and causes the bombs to crack or expand. The bombs are fully cured when they feel hard and make a hollow sound when tapped with a fingernail.

Alternative Mold Shapes

Silicone molds in shapes like hearts, stars, and shells work well and do not require the two-halves pressing technique. Fill each cavity to the top, press firmly with your fingers or the back of a spoon, and let cure for 6 to 8 hours. Silicone molds release the bombs easily when you flex the mold. A set of 6 silicone molds in assorted shapes costs $10 on Amazon. Metal molds produce a smoother surface finish than silicone but are harder to release; lightly coat metal molds with sweet almond oil before filling to prevent sticking.

Recipe 2: Citrus Energizing Bath Bomb

This recipe uses a blend of sweet orange and grapefruit essential oils for a bright, energizing scent. The color is a warm orange-yellow. Yield: 8 bath bombs.

Dry Ingredients

• 1 cup (224 g) baking soda
• 1/2 cup (112 g) citric acid
• 1/2 cup (112 g) Epsom salt
• 1/2 cup (60 g) cornstarch

Wet Ingredients

• 2 tablespoons (30 ml) fractionated coconut oil
• 1/2 teaspoon (2.5 ml) sweet orange essential oil (Now Foods, $7 for 30 ml)
• 1/2 teaspoon (2.5 ml) pink grapefruit essential oil (Plant Therapy, $9 for 15 ml)
• 1/8 teaspoon yellow mica powder + 1/8 teaspoon orange mica powder
• Witch hazel in a spray bottle

Mixing and Molding

Follow the same sifting, whisking, and mixing procedure as Recipe 1. Citrus essential oils are phototoxic, meaning they can cause skin sensitivity when exposed to sunlight. This is not a concern for a bath product (you are not in direct sunlight while bathing), but do not apply the undiluted oils to your skin before sun exposure. The mixing and molding process is identical to Recipe 1. These bombs cure in 4 to 6 hours at room temperature.

Recipe 3: Oatmeal and Honey Soothing Bath Bomb

This recipe is formulated for dry or sensitive skin. Colloidal oatmeal (finely ground oatmeal) soothes itching and irritation, and honey powder provides gentle moisturizing. The scent is a warm vanilla-honey. Yield: 8 bath bombs.

Dry Ingredients

• 1 cup (224 g) baking soda
• 1/2 cup (112 g) citric acid
• 1/4 cup (56 g) Epsom salt
• 1/4 cup (30 g) cornstarch
• 1/4 cup (20 g) colloidal oatmeal (Bob's Red Mill, $5 for 16 oz)

Wet Ingredients

• 2 tablespoons (30 ml) jojoba oil
• 1 teaspoon (5 ml) vanilla fragrance oil (Bramble Berry, $8 for 4 oz)
• 1 tablespoon (15 g) honey powder (Natures Garden, $6 for 4 oz)
• 1/4 teaspoon gold mica powder
• Witch hazel in a spray bottle

Special Mixing Notes

Colloidal oatmeal absorbs more liquid than the other dry ingredients. You may need 3 to 4 additional sprays of witch hazel to reach the right consistency. The honey powder should be mixed into the dry ingredients before adding the oil, which prevents it from clumping. Jojoba oil is technically a liquid wax, not an oil, and it closely mimics the skin's natural sebum. It costs more than sweet almond oil ($14 for 16 oz versus $9) but provides superior moisturizing for dry skin. These bombs cure in 6 to 8 hours due to the higher liquid content from the honey powder.

Common Problems and Fixes

Bath bombs crumble when unmolding: The mixture is too dry. Add 2 to 3 more sprays of witch hazel, mix thoroughly, and re-mold. Also check that you are packing the mold tightly; loose packing creates weak structural bonds between particles.

Bath bombs expand and crack in the mold: The mixture is too wet, and the acid-base reaction has started prematurely. This is irreversible for the current batch. For the next batch, reduce witch hazel by 2 to 3 sprays and work faster after adding the liquid ingredients. High humidity (above 60%) also causes premature activation; run a dehumidifier or make bath bombs on a dry day.

Bath bombs sink in the bathtub: This is normal. Bath bombs are denser than water and sink to the bottom. They continue to fizz while submerged. Floating bath bombs contain a higher proportion of cornstarch (which traps air) and are made with a lighter hand when packing the mold. To make floating bombs, increase cornstarch to 3/4 cup and reduce Epsom salt to 1/4 cup.

Bath bombs leave an oil ring on the tub: Reduce the carrier oil by 1 teaspoon in the next batch. Sweet almond oil and fractionated coconut oil are less likely to leave rings than heavier oils like olive oil or avocado oil. Rinse the tub with hot water and a drop of dish soap immediately after bathing to prevent residue buildup.

Bath bombs lose scent after 2 weeks: Fragrance oils and essential oils evaporate over time. Store bath bombs in airtight containers (glass mason jars with tight lids or heat-sealed cellophane bags) at room temperature. Properly stored bath bombs retain their scent for 3 to 4 months. Adding the fragrance oil at the end of the mixing process (after the witch hazel) rather than at the beginning also helps preserve scent strength.

Packaging Ideas for Gifts and Storage

Store-bought bath bombs come in individual wrappers or boxes that cost $0.50 to $1.50 per unit. You can package homemade bombs for $0.10 to $0.25 per unit with materials from Amazon or Uline.

Individual Packaging

• Shrink wrap bags: 4x6 inch PVC shrink wrap bags, 200-count, $12 on Amazon ($0.06 per bag). Place the bath bomb in the bag, use a heat gun ($15 at Harbor Freight) to shrink the film tightly around the bomb. This is the most professional-looking option and protects against moisture.
• Cellophane bags with twist ties: 3x5 inch cello bags, 100-count, $8 on Amazon ($0.08 per bag). Add a small label or tag with the scent name and ingredients list. Less airtight than shrink wrap, but adequate for bombs that will be used within 2 months.
• Mason jars: 4 oz quilted jelly jars, 12-count, $18 on Amazon ($1.50 per jar). Place one bath bomb per jar with a square of parchment paper between the bomb and the metal lid (the lid can react with the citric acid over time). Reusable and attractive for gifts.

Gift Set Packaging

A gift box of 4 bath bombs in different scents costs $3 to $5 in packaging materials and makes a practical gift. Use a kraft paper box (4x4x4 inches, 50-count, $20 on Amazon, $0.40 per box) lined with crinkle cut paper ($8 for 1 lb on Amazon). Place each bomb in a cellophane bag, arrange them in the box, and close with a ribbon. Add a small card listing the scents and ingredients. Total gift cost: $3.20 to $5.40 in materials (including the bath bombs themselves at $0.80 each) for a gift that would retail for $30 to $40.

Per-Bath-Bomb Cost Breakdown

Based on bulk Amazon pricing for all ingredients:

• Baking soda: $0.10 per bomb
• Citric acid: $0.18 per bomb
• Epsom salt: $0.13 per bomb
• Cornstarch: $0.03 per bomb
• Carrier oil: $0.18 per bomb
• Essential oil: $0.15 to $0.40 per bomb (varies by oil)
• Colorant: $0.02 per bomb
• Witch hazel: $0.03 per bomb

Total per bomb: $0.82 to $1.07 depending on the essential oil used. The initial investment in bulk ingredients is $60 to $80, but this produces 80 to 120 bath bombs. The cost per bomb drops to $0.60 to $0.80 once you have purchased the base ingredients and only need to restock essential oils and colorants.

Safety Considerations

Citric acid is a mild irritant. Wear a dust mask when measuring and sifting to avoid inhaling the fine powder, which causes coughing and throat irritation. Nitrile gloves prevent the oils and colorants from drying your skin during mixing. If you have sensitive skin, test a finished bath bomb by dissolving half of one in a bowl of warm water and applying a small amount to your inner forearm. Wait 24 hours; if no redness or itching develops, the bomb is safe for full-body use.

Do not use bath bombs in hot tubs or jetted tubs. The citric acid and baking soda residue can clog jet mechanisms and damage the pump. The oils in bath bombs also leave a film on hot tub filters that reduces filtration efficiency. Bath bombs are designed for standard bathtubs only.

Keep bath bombs away from pets and children. The essential oils that make them smell appealing to humans are toxic to dogs and cats if ingested. Citric acid causes stomach upset in quantities larger than a few grams. Store bath bombs in a cabinet or closet that pets cannot access.