TL;DR
Common guidance is twice a year for the outside of residential windows and about every three months for the inside. Exposure moves that more than anything else -- a window facing a gravel road or a stand of trees may need four passes a year while a sheltered north face gets by with one.
Inside and outside are two different jobs
The outside of a window faces weather. Rain carries dust down the glass and dries in streaks, pollen coats it in spring, road grit blows onto it, and hard water from sprinklers leaves mineral spots that etch if they sit.
The inside faces the household. Cooking film, fingerprints, pet nose marks, dust, and condensation residue are the usual suspects, and they build slowly and evenly rather than in weather events.
That is why the two surfaces run on different schedules and often need different approaches.
How often should you wash windows?
Twice a year outside for most homes -- typically once after pollen season ends and once before winter -- and quarterly inside. Increase to three or four times a year outside if you are near a gravel road, a construction site, heavy tree cover, or if sprinklers hit the glass. Sheltered windows can go longer.
What changes the schedule
| Condition | Effect on the outside schedule |
|---|---|
| Heavy tree cover or pollen | Add a spring pass |
| Gravel road or unpaved drive | Every 3 to 4 months |
| Sprinklers hitting the glass | Sooner -- hard water spots etch over time |
| Nearby construction | As needed, dust is abrasive |
| Coastal salt air | Every 3 months |
| Sheltered north-facing wall | Once a year is often enough |
| Wood smoke in heating season | Add a pass after the season |
Hard water is the one to take seriously. Mineral deposits left by sprinkler overspray bond to glass, and after long enough they stop being a cleaning problem and become permanent etching that only polishing or replacement addresses.
Does it matter beyond appearance?
Yes, in two ways. Dirty glass measurably reduces daylight coming into a room, which is why a house feels dimmer in late winter than it did in autumn. And grit left on the glass and in the frame is abrasive, so it grinds against the sash and the weatherstripping every time the window is opened.
Clean glass does not treat, prevent, or cure anything, and a window's condition has no bearing on health claims. It affects light, appearance, and how well the window's moving parts hold up.
How do you wash windows without streaks?
Work on a cloudy day or a shaded side so the solution does not dry before you squeegee it. Wash with a little dish soap in warm water, pull the squeegee in overlapping strokes, wipe the blade after each pass, then dry the edges with a lint-free cloth. Streaks are almost always sunlight or too much soap.
Paper towels leave lint and are the second most common cause of streaking. A microfiber cloth or a well-worn cotton cloth works far better.
Skip commercial glass cleaner on the outside of very dirty windows -- there is too much soil for it, and it dries too fast. Soap and water first, glass cleaner only for touch-ups and interior work.
Cleaners to avoid on specific glass
Ammonia-based glass cleaner is fine on plain glass but should not go on tinted film, low-emissivity coatings, or any coated panel. It can degrade the film and haze the coating permanently.
Never mix cleaning products. Ammonia and bleach together release chloramine gas, and that combination happens more often than people think when someone sprays a glass cleaner over a surface they just bleached. Rinse thoroughly between products or use one product only.
Vinegar is a common household glass cleaner and works fine on the glass itself. Keep it off natural stone sills -- marble, travertine, and limestone etch permanently on contact with acid.
Do not use razor blades or abrasive pads on tempered or coated glass. Scratches from a blade are permanent and highly visible.
When to skip the ladder
Ground floor windows are a reasonable do-it-yourself job. Second and third story exterior glass is not, for most people.
Falls from ladders are a leading cause of serious home injury, and window washing is one of the higher-risk versions of it because you are reaching sideways with wet hands. Source: U.S. Consumer Product Safety Commission
Water-fed pole systems and telescoping squeegees can reach a second story from the ground on some homes. Where they cannot, that is a job worth hiring rather than improvising.
Where windows fit in a wider routine
Glass is only part of a window. The tracks and sills collect grit, pollen, and dead insects and are usually filthier than the pane, which is why how often to clean window tracks and sills belongs on the same day's list.
What hangs in front of the glass matters too -- dusty slats undo a clean window fast, and that is covered in how often to dust and deep clean blinds.
The glass and mirror care guide covers the technique side across the house, and how often to clean everything in a house sets these intervals beside every other one. When a whole house of windows has gone several years, that is usually when people look at house cleaning services for the interior reset.
A sequence that saves rework
Vacuum the tracks and sills first. Wet glass plus dry grit equals mud, and mud in a track is far worse than dust in a track.
Do the outside before the inside when you can, so you can see remaining marks from indoors and know which side they are on. Wiping in different directions on each side -- vertical outside, horizontal inside -- makes that even easier.
Finish with the frames and the sill, not before. Anything you clean before the glass will need doing again.
FAQ
How often should you wash windows?
Twice a year outside for most homes and about quarterly inside. Increase the outside schedule to three or four times a year near gravel roads, construction, heavy tree cover, coastal salt air, or where sprinklers hit the glass. Sheltered windows can often go a full year.
What is the best time of day to wash windows?
An overcast day, or the shaded side of the house, so the cleaning solution does not dry on the glass before you can squeegee it. Direct sun is the single most common cause of streaks. Early morning and late afternoon are the next best options on a clear day.
Why do my windows streak after cleaning?
Usually sunlight drying the solution too fast, too much soap in the water, or drying with paper towels that leave lint. Use a small amount of dish soap, work in shade, pull the squeegee in overlapping strokes while wiping the blade between passes, and finish edges with microfiber.
Can I use vinegar to clean windows?
Yes, diluted white vinegar works well on plain glass. Keep it off natural stone sills such as marble, travertine, and limestone, which etch permanently on contact with acid. Never combine it with bleach or a chlorine product, and rinse thoroughly if a bleach cleaner was used nearby.
Is ammonia glass cleaner safe on all windows?
No. Ammonia is fine on plain glass but can degrade window tint film and haze low-emissivity coatings permanently. Check whether your windows are coated or tinted before using it. Never let ammonia products meet bleach, since that combination releases chloramine gas.
How do you clean second story windows safely?
From the ground when possible, using a telescoping squeegee or a water-fed pole system. Ladder work with wet hands and sideways reach is one of the higher-risk household tasks, and falls from ladders cause serious injuries every year. Upper floors are reasonable to hire out.
Do sprinklers really damage windows?
Over time, yes. Sprinkler overspray leaves hard water minerals that bond to the glass, and repeated cycles build deposits that eventually etch the surface permanently. Adjusting the sprinkler heads away from the house is a more effective fix than any cleaning schedule.
Window count, height, exposure, and how long it has been since the last pass all change what a real job involves, so a general schedule only takes you so far. If you want an actual number for your home rather than a range, get a quote and we will walk you through what drives it.