The colon has two meanings and both are in use
1:64 on one label means one part concentrate to sixty-four parts water, which is sixty-five parts of solution. On another it means one part in sixty-four parts of finished solution, so sixty-three parts of water. A gallon of concentrate makes 65 gallons under the first reading and 64 under the second — a 1.6 percent difference that is far too small to notice in a bucket and large enough to matter across a year of invoices.
The form asks which reading applies before it asks anything else, because the answer changes every figure below it. At the default product A — a 128 fl oz jug at $18.50, labelled 1:64 — the cost per ready-to-use gallon is $0.2846 read one way and $0.2891 read the other. The page prints both so the size of the ambiguity is visible rather than assumed away.
The cheap jug is the expensive one
The three products in the defaults are set up the way a real chemical closet ends up. Product A is a gallon jug at $18.50 diluted 1:64, which is 14.45 cents a fluid ounce of concentrate. Product C is a gallon jug at $12.40 diluted 1:32, or 9.69 cents an ounce. C is the cheapest concentrate on the shelf by a third and it is the one that gets ordered.
A makes 65 ready-to-use gallons and costs $0.2846 each. C makes 33 and costs $0.3758 each — 32 percent more per gallon of the thing you actually spray. At 40 gallons a week the difference is $190 a year on one product, and a closet has eight or ten of them. Product B, a 32 oz bottle at $9.75 and 1:128, is by far the dearest concentrate here at 30.47 cents an ounce, and still comes second at $0.3023 a finished gallon, ahead of the cheap jug. Price per ounce and dilution move independently, and the ranking is not readable off either one alone.
What a bottle fill costs
A quart bottle filled from product A takes 0.49 fl oz of concentrate and costs about seven cents. From product C it takes 0.97 fl oz and costs about nine cents. Nobody will ever change their behaviour over two cents a bottle, and that is exactly why the comparison has to be made at the case level and at the year level instead. The per-bottle figure is there to make the concentrate volume concrete — half an ounce in a quart is a squirt, and a dispenser that is delivering twice that is not something anyone would notice by eye.
What this does not know
It does not know whether two products are interchangeable. A cheaper gallon of the wrong thing is not a saving, and cost per ready-to-use gallon is only a fair comparison between products you would genuinely use for the same task at the dilution you entered. Whether a given dilution does what you need it to do is a question for the label, the safety data sheet and the manufacturer, and this page answers none of it.
It also assumes the dispenser delivers the ratio on the tip. Wall dispensers drift as they age, water pressure moves them, and a worn tip runs richer than its marking. Catching a measured jug under the outlet for a timed fill and weighing the result is the only way to know what the ratio in the building really is — and if it turns out to be 1:48 rather than 1:64, every figure on this page for that product is a third out.
Questions people ask
Does 1:64 mean 64 parts of water or 64 parts in total?
Both readings are in common use and the label decides which one applies. One part to sixty-four parts of water is sixty-five parts of solution; one part in sixty-four total is sixty-three parts of water. The difference on a gallon of concentrate is 65 ready-to-use gallons against 64, which is 1.6 percent — small per bucket, constant across every bucket. The form makes you pick the reading before it calculates anything.
How many gallons does a gallon of concentrate make at 1:64?
Sixty-five, if the label means one part to sixty-four parts of water. Sixty-four, if it means one part in sixty-four parts of finished solution. At 1:128 it is 129 or 128; at 1:32 it is 33 or 32. The arithmetic is only ever the pack volume multiplied by that factor, which is why the ambiguity in the factor is the only thing worth being careful about.
Why is the cheaper jug more expensive?
Because the price is per jug and the value is per finished gallon. In the defaults a $12.40 jug at 1:32 makes 33 gallons at $0.3758 each, while an $18.50 jug at 1:64 makes 65 at $0.2846 each. The dearer jug is 32 percent cheaper for every gallon that comes out of a spray bottle. Pack price and concentration move independently, so the ranking cannot be read off either one alone.
How much concentrate goes in a 32 ounce spray bottle?
At 1:64 read as one to sixty-four parts water, 32 divided by 65, which is 0.49 fl oz — roughly half an ounce, with the rest water. At 1:128 it is 0.25 fl oz and at 1:32 it is 0.97. The form prints the concentrate and the water separately for whichever ratio and bottle size you enter, so the volumes are visible rather than inferred.
Does a stronger dilution clean better?
This page cannot say, and nothing in it should be read as saying so. It converts volumes and prices, nothing else. What dilution a product is used at, what it is used on, how long it needs to stay wet and what protection is worn are all set by the product label and the safety data sheet, and a ratio that fills a bottle is not a claim about what the bottle does.