Soft-Wash Mix & Dilution Calculator

Enter batch size, your on-hand SH stock %, and a target % to get exact stock, water, and surfactant volumes — with the dilution math shown. No signup.

Batch

Total volume of finished mix to fill the tank to.

Strengths

Your drum's actual % — lower it if the SH is old.

Where you want the finished mix.

Typical targets — adjust to your surface and product. Not a prescription.

Surfactant
Dose method

Typical 0.5 oz/gal. Set 0 if you add surfactant separately.

Enter your batch size and strengths to see your mix recipe.

Export
How this is calculated

This uses the standard dilution mass-balance of active chlorine — the same identity the trade calls "stock % ÷ total parts = final %". It is not a proprietary recipe; here is the whole thing:

V_stock = V_batch × (target % / stock %)
V_water = V_batch − V_stock
surfactant = V_batch × dose rate
confirmed % = (stock % × V_stock) / V_batch

Worked example. Fill a 50 gal batch to 3% from 12.5% stock SH: 50 × 3/12.5 = 12 gal SH, 50 − 12 = 38 gal water, and at 0.5 oz/gal, 0.5 × 50 = 25 oz surfactant.

Stock % must exceed target %. You can only dilute down — if your on-hand strength is at or below the target, no recipe is possible. Stock sodium hypochlorite also degrades over time, so enter your drum's real on-hand % (often lower than the label) rather than a fixed value.

Surface presets are advisory. Typical targets — adjust to your surface and product. Not a prescription. They prefill the target field and stay fully editable — your number always wins.

Sources

  1. Soft Wash Mix Calculator. Southeast Softwash. Retrieved .
  2. Soft Wash Dilution Calculator. Wash Basics. Retrieved .
  3. Soft Washing Dilution & Mix Ratios. SoftWash UK. Retrieved .

Get early access

Fieldwynn is the field-first app we are building for small crews — simple in the truck, powerful in the back office. It is not out yet; join the early-access list and be first when it launches for your trade.