House wash mix calculator
Use a lighter SH percentage for siding, render, trim, gutters, and general organic staining. Many house wash mixes sit around 1.0% to 1.5% SH at the surface.
FREE SOFTWASH MIX CALCULATOR
Softwash Calculator for SH Mix Ratios
Work out SH, bleach, and water ratios for house washing, roofs, concrete, siding, driveways, and pavers.
Mix calculator
Enter your SH strength, target mix, and batch size.
Mix ratio1 : 7.5
1 part SH to 7.5 parts water
For 5.0 gal0.6 gal SH + 4.4 gal water
Same ratio works for liters.
House wash mix1.0% - 1.5% SH
Concrete mix3.0% - 4.0% SH
Roof wash mix4.0% - 6.0% SH
Built into WashBase
Turn mix math into quotes, jobs, and follow-ups.
WashBase helps pressure washers calculate mixes, estimate surface area, send quotes, track jobs, and follow up without rebuilding the same workflow every time.
Soft Wash Mix Ratios Cheat Sheet
| Application | Target SH Strength | Common Batch Mix Ratio (using 12.5% SH) |
|---|---|---|
| Vinyl Siding / House Wash | 1.0% - 1.5% | 1 : 7.3 |
| Concrete / Driveways | 3.0% - 4.0% | 1 : 2.1 |
| Roof Cleaning | 4.0% - 6.0% | 1 : 1.1 |
| Patios / Pavers | 2.0% - 3.0% | 1 : 3.2 |
| Pre-treat / Post-treat | 2.0% - 4.0% | 1 : 2.1 to 1 : 5.25 |
Roof wash mix calculator
Roof cleaning usually needs a stronger sodium hypochlorite mix because algae, moss, and lichen sit deeper on tile or shingle surfaces.
Concrete and driveway mix calculator
Concrete, pavers, and driveways often need a medium-strength bleach dilution for pre-treating or post-treating after pressure washing.
Sodium Hypochlorite Dilution Formula
To find your mix ratio, divide your starting chemical strength by your target mix strength, then subtract 1. For example, if you have 12.5% bleach and want a 2% mix: (12.5 / 2) - 1 = 5.25. You need 1 part bleach to 5.25 parts water.
Softwash Mix Calculator FAQs
What is an SH mix calculator?
An SH mix calculator works out how much sodium hypochlorite and water you need to hit a target softwash strength. Enter your starting SH percentage, target mix percentage, and batch size to calculate the ratio.
How do you calculate a softwash mix ratio?
Divide your starting sodium hypochlorite strength by your target SH strength, then subtract 1. For 12.5% SH to a 2% target mix, (12.5 / 2) - 1 = 5.25, so use 1 part SH to 5.25 parts water.
What SH percentage should I use for house washing?
Many house wash mixes land around 1.0% to 1.5% SH at the surface, depending on staining, surface type, dwell time, weather, and local safety rules.
What SH percentage should I use for roof cleaning?
Roof cleaning commonly uses stronger softwash mixes, often around 4% to 6% SH. Always check surface guidance, protect plants, and follow chemical safety rules.
What sodium hypochlorite ratio should I use for concrete?
Concrete and driveway cleaning often uses a 3% to 4% SH target mix for pre-treating or post-treating. With 12.5% SH, that is roughly 1 part SH to 2.1 to 3.2 parts water.
Is sodium hypochlorite the same as bleach?
Sodium hypochlorite is the active ingredient in bleach. Softwash contractors often use stronger SH than household bleach, so dilution matters.
Can I use this as a bleach dilution calculator?
Yes. Enter your starting bleach or sodium hypochlorite strength, enter the target SH percentage you want, and the calculator gives the water-to-chemical ratio.