How to Make Natural Laundry Soap | Simple DIY Recipe That Works

Most store-bought detergents are packed with unwanted chemicals. Making your own takes about 20 minutes of active work, a few common ingredients, and one overnight rest. The payoff is a gentle, effective cleaner that keeps synthetic chemicals out of your wash.

What You Need: Ingredients and Equipment

• Bar soap — Castile soap (like Dr. Bronner’s), Fels-Naptha, or any simple bar without synthetic fragrance. A single 4–5 ounce bar makes one batch.
• Washing soda — Sodium carbonate (Arm & Hammer Super Washing Soda). This softens water and boosts cleaning power. Not baking soda.
• Borax — Sodium tetraborate (20 Mule Team Borax). Helps lift stains and control odors. Optional but common.
• Hot water — Tap water heated to near boiling dissolves the soap fully.
• Equipment — A box grater or food processor, a large pot, a 1–2 gallon container with a lid, a long spoon.

If you’d prefer to skip the DIY, read our roundup of the best eco-friendly laundry soaps on the market — we tested seven brands to find the ones worth buying.

The Basic Liquid Natural Laundry Soap Recipe

This gel-like liquid works in standard and HE machines when dosed correctly.

Step 1: Grate the soap. Run the bar through a fine box grater or food processor until you have fine flakes. As DIY Natural explains, finely grated soap dissolves easily in any water temperature.

Step 2: Melt the soap. Bring 3 cups of water to a near boil. Add soap flakes and stir until fully melted — about 2–3 minutes. Reduce heat if needed.

Step 3: Add the builders. Stir in 1/2 cup washing soda and 1/2 cup borax (optional) until dissolved — the mixture will thicken. Wear gloves if you have sensitive skin.

Step 4: Dilute and rest. Fill your storage container halfway with very hot water. Pour in the soap mixture and stir. Top off with more hot water. Cover loosely and let sit undisturbed for 24 hours — it will thicken into a gel.

Step 5: Shake before each use. Separation is normal; shake or stir vigorously before each load.

Using It in HE and Standard Washers

Use 1/2 cup per load for soiled laundry; cut to 1/4 cup for lightly worn clothes. Overdosing causes residue in HE machines. Pour gel into the liquid-detergent dispenser or add directly to the drum once the machine fills. For powder detergent, mix 1/2 cup grated soap with 1/2 cup washing soda and 1/2 cup borax, store in a sealed jar, and use 2 tablespoons per load. For cold water, stir the powder into warm water first.

Common Problems and Fixes

Soap residue on clothes. Reduce dose by half and ensure soap is finely grated. Run an empty hot cycle with a cup of white vinegar to clear the machine.

Mixture too thick or too thin. Let it sit up to 48 hours. If still watery, add 1–2 tablespoons washing soda in hot water and stir. If too thick, add hot water and shake.

Clumping in storage. Keep the container sealed in a cool, dry place. Break clumps with a fork before use.