What each of the five preset recipes is for, why the chemistry differs across them, what the volume math actually represents when you scale a recipe up or down, and the small set of cases where a recipe in the calculator is not the right choice for your glass.
What the Solution Calculator does, in five points:
Every recipe in the Solution Calculator is one I have personally mixed, used on a job, and adjusted at least once. The chemistry behind each is documented in the encyclopedia. The math behind the scaling is honest unit conversion. What it cannot do is tell you which recipe your particular pane wants — that is what the rest of the site is for.
The first window cleaning recipe I learned was wrong. It was 2014, my second week on a route in Milwaukee, and the senior cleaner I was apprenticing under handed me a plastic spray bottle and said that's the mix. The bottle had no label. It contained a yellow-tinted liquid that smelled faintly of dish soap and strongly of ammonia. I used it for three months before I asked what was actually in it. The answer was a quarter-cup of Windex, a glug of Dawn, and tap water — the recipe a cleaner who had been on the job since 1988 had inherited from his predecessor, who had probably inherited it from his. It worked, sort of. It also left a faint ammonia residue on every dark-glass storefront we cleaned, which I started noticing once I knew to look.
The Solution Calculator is the tool we built so that conversation doesn't have to happen any more. Five canonical recipes, each one documented with its actual use case, scaled cleanly to whatever volume you need, in the units you actually have on the counter. This piece is the methodology behind it — what the recipes are, why the chemistry differs across them, what the volume math actually represents, and the small set of cases where a recipe in the calculator is not the right choice for your glass.
If you just want to mix the House Standard for a residential job, the calculator answers that question in about ten seconds. If you want to know why the recipe is what it is, this is the piece for that.
A window cleaning solution has exactly three jobs. It has to wet the glass evenly, lift dirt off the surface, and rinse cleanly so that nothing it brought to the work is left behind. Every variable in every recipe in the calculator exists because of one of those three jobs.
Wetting is the chemistry of breaking water's surface tension so the solution spreads in a continuous film instead of beading up. This is what surfactants do. Soap, detergent, and dish liquid are all surfactant systems. The wetting job needs very little surfactant — far less than the amount on the back of a dish-soap bottle, which is calibrated for emulsifying grease in a dishwasher full of cold water. On a window, two drops per gallon is enough.
Dirt lifting is the chemistry of getting accumulated grime — pollen, road film, cooking grease, plasticizer condensate, organic residue — off the glass surface and into solution. This is what surfactants also do, plus, in some recipes, the help of a mild solvent (alcohol) or a mild acid (vinegar, sulfamic acid, or in extreme cases CLR). The dirt-lifting job is what most homeowners think they're doing when they reach for a stronger cleaner. They are usually wrong about that. Most residential glass is not dirty enough to need help past basic surfactant chemistry.
Rinsing cleanly is the chemistry of getting the solution itself off the glass after it has done its job. This is the part most amateur recipes fail at. A solution that wets and lifts well but rinses poorly leaves a residue, the residue absorbs humidity, and within a day or two the homeowner is looking at streaks they will incorrectly attribute to a "streaky cleaner." The streak is the residue. The residue is the cleaner.
Distilled water is the rinse solution that solves the third problem most reliably. It contains no minerals, so when it evaporates it leaves nothing behind. Every recipe in the calculator uses distilled water — not because tap water is dramatic on every job, but because distilled water is the variable you can control, and a controlled rinse is the difference between consistent results and inconsistent ones.
Two drops of original Dawn dish soap per gallon of distilled water. That is the recipe the Solution Calculator opens to, the recipe printed in the how to wash a window properly article, and the recipe I have mixed on hundreds of jobs over twelve years.
The proportions are deliberately, almost aggressively, low on surfactant. Two drops per gallon — about 0.1 milliliters in 3,800 milliliters of water — is approximately a 0.003% solution by volume. By the standards of every consumer cleaner on a hardware-store shelf, that is nearly nothing. By the standard of what residential glass actually needs, it is exactly right.
The reason consumer cleaners contain ten to fifty times that concentration is because they are sold by the bottle, used once, and judged by the immediate visual result. A heavily surfactant-loaded solution lifts dirt fast on the first pass. It also leaves a measurable residue that the user does not notice on day one but starts to see on day three, when humidity reactivates the surfactant film and the streaks come back. The encyclopedia entry on streaks that come back overnight is the long version of this story. The House Standard is the recipe that doesn't have that problem because the surfactant load is too low to leave a meaningful residue.
The calculator caveat that matters here: original blue Dawn only. Ultra Dawn, Platinum Dawn, scented variants, antibacterial variants — all contain conditioners, fragrances, or moisturizers that will streak. The original blue formulation, which has been on shelves substantially unchanged since the 1970s, is the only one that scales down to two drops per gallon and rinses clean. This is the exact bottle on the shelf, no substitutions. I keep one bottle of original Dawn in my truck and one on a shelf in my kitchen, and the kitchen one has been the same bottle for about fourteen months because the actual usage rate is two drops at a time.
The Vinegar Cut — half distilled vinegar, half distilled water — is in the calculator because it has a specific job that the House Standard cannot do. It is not, despite what the internet will tell you, a primary glass cleaner. It is a maintenance pass for glass that has been over-cleaned with the wrong product, and that has accumulated a faint mineral or surfactant haze that needs a mild acid to dissolve.
The chemistry: acetic acid at 2.5% concentration (the working strength of the half-and-half cut) dissolves calcium carbonate at a slow rate that is compatible with quick contact times on glass. It also breaks the molecular bonds of soap-scum-style surfactant deposits and helps lift them off the surface. It does not, however, contain any surfactant of its own, which is why it cannot replace the House Standard for actual cleaning. A Vinegar Cut applied to dirty glass will dissolve mineral haze just fine and leave the dirt sitting there.
The proper sequence is clean first with the House Standard, rinse, then apply the Vinegar Cut as a maintenance pass on glass that you suspect has accumulated a residue from a previous bad cleaning product. The Vinegar Cut sits for thirty seconds, gets agitated with a clean microfiber, gets rinsed with plain distilled water, and then squeegees dry. This is the correct workflow. It is also a workflow most homeowners will never need to do, because most homeowners are not over-cleaning their glass.
I have my long-running editorial argument with Easton on this one. He thinks vinegar should not be on the calculator at all because of the risk of homeowners using it on tinted, low-E, or laminated glass that the acid can damage. I think the recipe is in wide enough use that we should document the correct version of it rather than pretend it doesn't exist. We compromised by including the Vinegar Cut with explicit caveats — no stone trim, do not use on coated glass, see the vinegar question piece for the long answer — and a "Conditional" rating that tells the user the recipe is appropriate only in specific circumstances.
The remaining three presets each address a specific working condition the House Standard cannot handle.
The Cold-Weather Mix — one cup of 70% isopropyl alcohol, two drops of Dawn, fourteen cups of distilled water — is for window cleaning at temperatures below 32°F. The alcohol depresses the freezing point of the solution so it does not flash-ice on contact with the glass, which is what happens when you spray plain water onto a sub-freezing pane. The exact alcohol-to-water ratio in the calculator is calibrated for temperatures down to about 20°F. Below that, the mix needs a higher alcohol fraction, which the calculator notes but does not automatically generate; below 20°F the work is genuinely dangerous and most professionals don't do it.
The Pro Concentrate — half an ounce of GG3 or Ettore Squeegee-Off concentrate per gallon of distilled water — is the trade-grade equivalent of the House Standard. The active ingredient in both GG3 and Squeegee-Off is a calibrated surfactant blend that contains less of itself per ounce than Dawn does, but is engineered specifically for windows rather than dishes. The bottled dilution recommendation is generally double what working cleaners actually use; the calculator's amount is what most pros run. This recipe makes sense for high-volume route work where the cost per gallon and the consistency of the mix matter; it does not particularly outperform the House Standard on a single residential job.
The Restoration Pass — four ounces of CLR Calcium Lime Rust in twelve ounces of distilled water — is the only recipe in the calculator that I genuinely want users to think twice before mixing. CLR is a phosphoric and lactic acid blend that will dissolve calcium carbonate deposits that the Vinegar Cut cannot touch. It will also damage tinted, low-E, and laminated glass, and on certain coated glass formulations the damage is immediate and irreversible. The Restoration Pass is a one-time treatment for badly built-up mineral etching on glass you have first verified is uncoated soda-lime — see Easton's tint identifier guide for the verification protocol.
The recipe gets a "Aggressive" rating in the calculator and an explicit test on a small corner first warning. If you are not sure, do not use it. If you are sure, follow the dwell time exactly — sixty seconds — and rinse twice with plain distilled water before squeegeeing. CLR left on glass for too long will start etching the surface itself, which is the exact problem you were trying to fix.
The calculator's central function is unit conversion. Every recipe is internally defined in milliliters per gallon of finished solution. When you ask the calculator to make 32 ounces of the House Standard, it converts 32 ounces to 946 milliliters, computes the ratio (946/3785, or about 0.25), scales each ingredient by that ratio, and converts the scaled milliliter values back into the most sensible output unit for each ingredient.
This last step — the unit selection — is the part of the calculator that took the longest to get right. A recipe scaled to 32 ounces should produce an answer like 0.5 drops of Dawn, 32 ounces of distilled water, except that 0.5 drops is not a thing you can dispense. The calculator's unit-selection logic rounds to the nearest sensible unit at the bottom and rounds to a whole drop count for any solution under about two gallons. For very small batches — a 4-ounce spray bottle, say — the recipe might round down to one drop, 4 ounces of distilled water, which is technically a higher concentration than the spec but is the closest the kitchen-dropper resolution can get.
The math is honest, in other words, but the rounding makes small batches slightly over-concentrated. This matters less than it sounds, because the House Standard is so dilute to begin with that even doubling the surfactant proportion still rinses clean. But it is worth knowing that the larger your batch, the more precisely the calculator can hit the nominal recipe.
The custom mode in the calculator is for the user who has their own recipe — passed down from a relative, picked up at trade school, accumulated over decades of route work — and wants the volume math without the chemistry editorial. You enter the ingredients, the amounts, the units, and the calculator scales the recipe to your target batch size with the same conversion logic the presets use.
The chemistry is your responsibility in custom mode. The calculator does not know whether your recipe makes sense. If you enter a half-cup of bleach and a quarter-cup of ammonia, it will dutifully produce a scaled recipe that contains both — and a chemist will tell you that the resulting chloramine vapor is a serious respiratory hazard. The calculator is a math tool, not a safety auditor. The chemistry of any recipe you bring to it is a chemistry you've already vetted.
For users who want to vet a custom recipe against the principles in the calculator, the rule of thumb is: surfactant load should be low (well under 0.1% by volume), the rinse should be distilled or deionized water, and acids and solvents should be present only when there's a specific job for them. Most working recipes that violate one of these principles can be improved by being moved closer to the House Standard. Most that violate two of them are leftover from an era when cleaners didn't think about residue.
The Solution Calculator gives you a recipe at a volume. It does not tell you:
The recipe is the foundation. The recipe is not the work. There is a craft on top of the chemistry that takes years to learn, and the Solution Calculator's job is to get the chemistry out of the way so the craft can do what the craft does.
That cleaner in Milwaukee in 2014, with the unlabeled spray bottle of yellow ammonia mix? He was a good cleaner. The recipe was wrong, but the technique was right, and the technique was carrying the recipe. Most amateur cleaning failures are the opposite — the recipe is fine, the technique is what's failing. The Solution Calculator is the easy half of the job. The hard half is on the rest of the site.
Mara Whitfield is the senior editor at Window Washing Guide and a twelve-year veteran of the trade. She has cleaned the glass on three of the ten tallest buildings in North America, written equipment reviews for Pro Window Cleaner Magazine, and personally tested every method in this piece. She lives in Chicago, where the water is famously, awfully hard.
Mara is the senior editor at Window Washing Guide and a twelve-year veteran of the trade. She has cleaned the glass on three of the ten tallest buildings in North America, written equipment reviews for Pro Window Cleaner Magazine, and personally tested every method in this piece. She lives in Chicago, where the water is famously, awfully hard.