Dilution Ratios for Floor Scrubbers: Ratio Math, Conversion Chart and Tank Fill Examples

Key takeaways

• Ounces of concentrate equals gallons of water times 128 divided by the second number of the ratio.
• At 1:64 you add 2 oz per gallon, at 1:128 you add 1 oz per gallon, and at 1:256 you add half an ounce per gallon.
• Mix by measuring the real fill volume, not the tank's nominal size.
• Over-concentration leaves sticky residue that makes floors slippery and dirty faster, and it can double chemical spend.
• The chemical label sets the dilution, and the scrubber maker's compatibility guidance sets what can go in the tank.

To convert a dilution ratio to ounces per gallon, divide 128 (the ounces in a US gallon) by the second number in the ratio. A 1:64 ratio is 2 oz of concentrate per gallon of water, 1:128 is 1 oz per gallon, and 1:32 is 4 oz per gallon. Multiply by the gallons in your scrubber tank to get the dose for a full fill.

A dilution ratio is the proportion of chemical concentrate to water in the use solution. "1:64" on a label means 1 part concentrate to 64 parts water. The parts can be any unit, as long as both sides use the same unit.

The ratio math

Three formulas cover almost every floor care mixing job:

• Ounces per gallon = 128 / ratio number
• Ounces for a tank = gallons of water x 128 / ratio number
• Milliliters per liter = 1,000 / ratio number

So for a 1:100 product: 128 / 100 = 1.28 oz per gallon, or 1,000 / 100 = 10 ml per liter.

A quick note on "parts". Most labels mean 1 part concentrate added to the stated parts of water. A few mean 1 part in a total volume. At floor care dilutions (1:32 and weaker) the difference is under about 3 percent and does not matter in practice. At strong dilutions like 1:4 for a stripper, it does, so read the label wording.

The dilution calculator runs these conversions for any ratio and tank size.

Dilution conversion chart

Values rounded. US fluid ounces and US gallons; metric in ml per liter.

Note how the bottom of the chart works: going from 1:256 to 1:128 doubles the chemical. A small "extra splash" on a super-concentrate can easily put you at two or three times the label rate.

Worked tank fill examples

Use the volume you actually put in the tank. If the operator fills a 20 gal solution tank to the 15 gal mark, the dose is for 15 gal. Tank size ranges below are typical: micro 1 to 3 gal, walk-behind 8 to 30 gal, ride-on 25 to 60 gal.

Example 1: micro scrubber, 2.5 gal at 1:128

2.5 x 128 / 128 = 2.5 oz (about 74 ml). Small doses like this are where errors are biggest in percentage terms, so use a marked dosing cup or a pre-measured pump bottle, not a guess.

Example 2: walk-behind, 12 gal at 1:128

12 x 128 / 128 = 12 oz (about 355 ml) of neutral cleaner.

Example 3: large walk-behind, 25 gal at 1:64

25 x 128 / 64 = 50 oz (about 1.5 liters) of general purpose cleaner.

Example 4: ride-on, 40 gal at 1:256

40 x 128 / 256 = 20 oz (about 590 ml) of super-concentrate neutral cleaner.

Example 5: metric tank, 45 L at 1:200

45 x 1,000 / 200 = 225 ml of concentrate.

Example 6: correcting a half-full tank

A 20 gal tank still holds 8 gal of solution mixed at 1:128. You top up with 12 gal of fresh water. Add chemical only for the new water: 12 x 128 / 128 = 12 oz. Do not add a "full tank" dose of 20 oz, which would push the whole tank to roughly 1:90, about 40 percent over the label rate.

How to mix a tank correctly

1. Check the label for the dilution for automatic scrubber use. Some labels give a range (for example 1:64 to 1:128); start at the weaker end.
2. Fill the solution tank with water first, to a known mark. Water first reduces foam and splashing.
3. Measure the concentrate with a marked cup, a portion-control pump, or a wall-mounted dispenser. Never pour from the jug.
4. Add the concentrate to the water and let the machine's flow mix it, or gently stir if the label calls for it.
5. Label any secondary container as required by your hazard communication program.
6. Wear the PPE the SDS calls for at concentrate strength, usually gloves and eye protection.

If you use a wall dispenser or an on-board chemical dosing system, check its output once a quarter by catching and measuring a known volume. Worn metering tips and wrong tip colors are common sources of silent over- or under-dosing.

Over-concentration: the expensive habit

Operators over-concentrate because they believe more chemical cleans better. Beyond the label rate it usually does the opposite.

Residue. The excess surfactant and builders that the squeegee does not recover dry as a film. The floor feels tacky, shows footprints, and gets dirty faster because the film holds soil. On the next scrub, the film re-wets and can foam. See residue and rinsing.

Slipperiness. A wet floor with surfactant residue can be more slippery than one cleaned at the right rate, which affects slip resistance.

Foam. Extra surfactant is the second most common cause of foam after using the wrong product. See defoamers and foam control.

Finish damage. Over-concentrated alkaline cleaners soften and dull floor finish over weeks.

Cost. This is easy to model.

Scrubber Guide model: the cost of the "glug"

Assumptions: one 25 gal walk-behind, two full fills per day, 260 working days a year, a cleaner labeled 1:128, and a concentrate price of $25 per gallon (an assumption for illustration, your price will differ).

Formula: gallons of concentrate = solution gallons / ratio number. The direct overspend from a double dose here is about $2,500 per machine per year, before counting the added rinse labor, recoating and vacuum motor wear from foam. A $20 dosing pump pays for itself in days.

Under-concentration is also a problem, though a smaller one: the floor looks clean wet, then dries dull because soil was moved around rather than lifted. If you need more cleaning power, change the pad or brush first, then step up the dilution within the label range.

Water quality and temperature

Hard water reduces the effectiveness of some surfactants and can leave mineral spots; some products compensate with water conditioners. Warm water speeds cleaning of greasy soils but can increase foam and must stay within the maximum temperature in the scrubber manual. Never put very hot water in a machine not rated for it.

Frequently asked questions