02 / WINDOWS
The best window insulation kits, by published coverage
Shrink film is the highest-return fix on a single-pane window. The only real decision is how much film you need and how tough it has to be.
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For most houses the right kit is heavy-duty shrink film sized to the number of windows you actually have: a three-window kit for one room, a rolled kit for a whole house. Buy the puncture-resistant film if you have pets or children. Film works by trapping a still layer of air against the glass, so it must be sealed all the way around.
Window film is the cheapest genuinely effective thing in this entire category, and it is also the fix people most often do badly. Two things decide the outcome: whether you bought enough film, and whether the tape held. Everything below is organized around those two.
How film actually works, in one paragraph
The film is not an insulator. What insulates is the pocket of still air trapped between the film and the glass — the same principle as a double-glazed unit, at about one percent of the cost. Which is why a film with a gap in the tape does close to nothing: air that can circulate is not still air. It also means the film has to be reasonably taut, so it does not touch the glass and bridge the gap. There is a longer version in does window film actually work.
Match the part to your gap
Measure at the widest point. Then read across. If your measurement sits on a boundary, take the larger band — a seal that is slightly too big compresses, and one that is too small does nothing at all.
| Your gap | Part type | Our pick | Price |
|---|---|---|---|
| 3 windows, kids or pets in the house | Heavy-duty film kit | Duck MAX Strength Heavy Duty Insulating Film Window Kit, 3-WindowPuncture-resistant film, published at 62 x 126 in. The standard film does not survive a cat. | CHECK PRICE |
| 5 ordinary windows | Standard film kit | 3M Indoor Window Insulator Kit, Five PackThe Scotch mounting tape is the reason this kit stays up when cheaper ones peel. | CHECK PRICE |
| A whole house | Rolled film, cut to size | Duck Rolled Window Insulation Kit, up to 15 WindowsPublished for up to 15 windows. No measuring — apply, shrink, then trim. | CHECK PRICE |
| One bad window | Single-window kit | Frost King V73H Shrink Film Window KitPublishes which frame materials it mounts to, and includes nails as well as tape. | CHECK PRICE |
Work out your coverage before you buy
- 1Measure the height and width of each window frame you intend to cover — the frame, not the glass, because the tape goes on the frame.
- 2Add about 2 inches to each dimension for handling slack.
- 3Add the areas up. That is the film area you need.
- 4Compare against the kit's published sheet size rather than its window count: a kit sold as 'five windows' assumes 3 by 5 foot windows, and yours may be bigger.
- 5Buy about 15 percent more than you calculated. Every film job wastes some, and running out mid-window means the room stays cold until the next delivery.
| Film type | Survives | Fails against |
|---|---|---|
| Standard shrink film | Normal room use, curtains that do not touch it | Cats, toddlers, a curtain rail resting on it |
| Heavy-duty (MAX Strength) film | Pets, children, being brushed past daily | Deliberate contact with anything sharp |
| Rolled film | Odd-shaped and tall windows | Same as its film weight — the format changes, not the material |
Quick picks
Ranked for fit, not for hype. Tap a row to jump to the full write-up, or go straight to the listing.
| # | Product | Best for | Gap range | Price |
|---|---|---|---|---|
| 1 | Duck MAX Strength Heavy Duty Insulating Film Window Kit, 3-WindowThicker, puncture-resistant film for the case that kills ordinary window kits: something touches the film. | Households with kids or pets | Covers three windows within a published 62 in x 126 in of film | CHECK PRICE |
| 2 | 3M Indoor Window Insulator Kit, Five PackThe kit most people mean when they say window film, with the Scotch mounting tape that is the actual reason it holds. | The default film kit | Five windows up to a published 3 ft x 5 ft each | CHECK PRICE |
| 3 | Duck Rolled Window Insulation Kit, up to 15 WindowsFilm on a roll rather than in folded sheets — no measuring, cut the excess after it is up, and enough for up to fifteen 3 by 5 windows. | A whole house | Up to fifteen published 3 ft x 5 ft windows | CHECK PRICE |
| 4 | Duck MAX Strength Window Insulation Kit, 5-WindowThe same heavy film in a 62 by 210 inch roll — cut to size, which is cheaper per window than buying three small kits. | A whole floor of windows | Published 62 in x 210 in of film, cut to fit up to five windows | CHECK PRICE |
| 5 | Frost King V73H Shrink Film Window KitThe budget kit that shrinks tight with an ordinary hair dryer and mounts to metal, painted wood, varnish or vinyl-clad frames. | Single-window budget fix | One window; published for indoor mounting on most frame types | CHECK PRICE |
| 6 | 3M Indoor Window Insulator Kit, Two PackThe two-window box: the right way to find out whether film solves your problem before committing a whole house to it. | Trying it on one room | Two windows up to a published 3 ft x 5 ft each | CHECK PRICE |
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Households with kids or pets
Duck MAX Strength Heavy Duty Insulating Film Window Kit, 3-Window
Published gap range
Covers three windows within a published 62 in x 126 in of film
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Thicker, puncture-resistant film for the case that kills ordinary window kits: something touches the film.
Where the number comes fromDuck publishes the film area (62" x 126") and the window count, not a gap figure — a film kit does not seal a gap, it traps a layer of still air in front of the whole window. Measure the frame, not the draft.
- Published film size
- 62" x 126"
- Windows covered
- 3
- Film
- Heavy duty, puncture resistant
- Install
- Indoor, hair dryer shrink
- Model
- 284351
- Mounting
- Double-sided tape to the frame, shrunk tight with a hair dryer
What it does well
- Survives a cat, a toddler or a curtain rail — the standard film does not
- Shrinks genuinely wrinkle-free with an ordinary hair dryer
- Tape and film in one box, nothing else to buy
Where it fails
- The tape can lift paint on release; test a corner first
- Will not stick to a damp or dusty frame, which is most basement windows
- Seals the window shut for the season by design
Who this is forThree drafty windows in a house where the film is going to get touched.
The default film kit
3M Indoor Window Insulator Kit, Five Pack
Published gap range
Five windows up to a published 3 ft x 5 ft each
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The kit most people mean when they say window film, with the Scotch mounting tape that is the actual reason it holds.
Where the number comes from3M publishes the window count and the per-window size the kit is designed for. Like every film kit it insulates the whole opening rather than sealing a measured gap.
- Windows covered
- 5
- Per window
- 3 ft x 5 ft
- Tape
- Scotch window film mounting tape
- Install
- Indoor
- Also reduces
- Condensation and frost buildup, per 3M
- Mounting
- Scotch double-sided window film tape, hair dryer shrink
What it does well
- The mounting tape is the best in the category and it is why the film stays up
- 3M publishes condensation and frost reduction, not just draft blocking
- Widely stocked, so a mid-winter top-up is easy
Where it fails
- Standard-weight film punctures easily
- Pre-sized sheets waste film on small windows
- Removing the tape from soft old paint takes patience
Who this is forFive ordinary windows and no cat.
A whole house
Duck Rolled Window Insulation Kit, up to 15 Windows
Published gap range
Up to fifteen published 3 ft x 5 ft windows
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Film on a roll rather than in folded sheets — no measuring, cut the excess after it is up, and enough for up to fifteen 3 by 5 windows.
Where the number comes fromDuck publishes the coverage (up to 15 windows at 3 ft x 5 ft) and the roll format. As with all film, it insulates the opening rather than sealing a measured gap.
- Windows covered
- Up to 15
- Format
- Roll, cut after application
- Tape
- Included
- Install
- Indoor
- Model
- 288069
- Mounting
- Window tape included, hair dryer shrink
What it does well
- No measuring — apply, shrink, then trim
- Best price per window in the whole category
- Roll format handles tall or narrow windows folded sheets waste
Where it fails
- Standard-weight film, not the MAX Strength material
- Fifteen windows is a real day of work
- Trimming after shrinking takes a steady hand near the tape line
Who this is forA whole house of single-pane windows and one determined weekend.
A whole floor of windows
Duck MAX Strength Window Insulation Kit, 5-Window
Published gap range
Published 62 in x 210 in of film, cut to fit up to five windows
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The same heavy film in a 62 by 210 inch roll — cut to size, which is cheaper per window than buying three small kits.
Where the number comes fromDuck publishes the film dimensions and the window count. Cutting to size is the point: you are not limited to a pane-shaped sheet.
- Published film size
- 62" x 210"
- Windows covered
- Up to 5
- Film
- Heavy duty
- Cut
- To size, with scissors
- Model
- 287455
- Mounting
- Double-sided tape, hair dryer shrink
What it does well
- Cheapest per window of the heavy-duty kits
- Cut-to-size handles odd shapes small kits waste film on
- One box does most of a floor
Where it fails
- You are measuring and cutting rather than unfolding a pre-cut sheet
- Same tape-on-paint caution as every film kit
- Leftover film is awkward to store flat
Who this is forFour or five windows to do in one weekend.
Single-window budget fix
Frost King V73H Shrink Film Window Kit
Published gap range
One window; published for indoor mounting on most frame types
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The budget kit that shrinks tight with an ordinary hair dryer and mounts to metal, painted wood, varnish or vinyl-clad frames.
Where the number comes fromFrost King publishes the mounting surfaces the kit works on (metal, painted, varnished wood, vinyl clad) and includes double-face tape or nails. No gap figure applies.
- Windows covered
- 1
- Frames
- Metal, painted, varnished wood, vinyl clad
- Fixing
- Double-face tape or nails supplied
- Finish
- Shrinks wrinkle free
- Install
- Indoor
- Mounting
- Double-face tape or nails, hair dryer shrink
What it does well
- Publishes which frame materials it mounts to — most kits do not
- Nails as an alternative to tape, which matters on old varnish
- Cheapest way to film one bad window
Where it fails
- Thin film, easily punctured
- One window per box gets expensive fast
- Clarity is a step below the 3M and Duck films
Who this is forOne bad window, or an old frame where tape alone will not hold.
Trying it on one room
3M Indoor Window Insulator Kit, Two Pack
Published gap range
Two windows up to a published 3 ft x 5 ft each
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The two-window box: the right way to find out whether film solves your problem before committing a whole house to it.
Where the number comes from3M publishes the window count and nominal window size. No gap figure applies to film.
- Windows covered
- 2
- Per window
- 3 ft x 5 ft
- Tape
- Scotch window film mounting tape
- Install
- Indoor
- Use
- Single room trial
- Mounting
- Scotch double-sided tape, hair dryer shrink
What it does well
- Cheap enough to test the idea on the worst room
- Same tape as the five-pack
- Two windows is one evening, not a project
Where it fails
- Worst price per window in the range
- Standard film, so same puncture caveat
- You will end up buying the big kit anyway if it works
Who this is forOne cold room and a reasonable suspicion that film will fix it.
What we would skip, and why
Nobody in this category ever declines to recommend something. That is what makes universal praise worth ignoring. Here is what we would not buy.
Exterior film kits on a window you can reach from inside
Outdoor kits exist and they are harder to fit, harder to keep sealed, and get destroyed by the first storm that catches a loose corner. Film works because it traps still air against the glass — the inside face does that just as well and lives in a benign environment.
Any film kit on a window with visible condensation or damp frames
The mounting tape will not bond to a damp frame, and sealing film over a window that is already condensing traps that moisture where you cannot see it. Fix the moisture first. This is the single most common reason a film kit fails within a week.
Film on a window you need to open
A film kit seals the window shut for the season. That is not a flaw, it is the mechanism — but it rules out a bathroom, a kitchen window over the hob, and any window that is your emergency egress. Use weather stripping tape or rope caulk on those instead.
How we picked
- Compare on published film area and window count, since that is what determines whether a kit covers your house.
- Separate heavy-duty film from standard film, because puncture resistance is the difference between one season and three.
- Note which kits publish their frame compatibility — most do not, and it matters on old varnished wood.
- Rank on coverage per dollar for equivalent film weight.
- Say which kit we would not buy, and why.
We have not tested these products and we do not claim to have. The full method, including what we refuse to claim, is on how we pick.
Complete the kit
The parts that decide whether the seal you just bought actually holds. Skip these and you will be doing the job again in March.
Removing old weatherstrip adhesive
Goo Gone Pro-Power Adhesive Remover, 8 oz
The step everybody skips: the new tape will not stick to the residue the old tape left behind.
Seasonal window sealing
Frost King B2 Mortite Fingertip Caulking Cord, 1/8 in x 90 ft
Rope caulk: pliable putty you press into a gap in October and peel out in April, leaving no adhesive behind.
Door and window frame sides
fowong V Seal Weather Stripping, 1/2 in x 19 ft
V-strip folds into the gap and springs back, so it seals a jamb that never closes to exactly the same place twice.
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Fitting it so it looks like glass, not like a bag
- 1Clean the frame with alcohol and let it dry completely. Not spray cleaner — it leaves a film the tape will not bond through.
- 2Run the double-sided tape around the frame in one continuous path, with no breaks at the corners. A break is a leak and the whole kit stops working.
- 3Cut the film about 2 inches oversize all round, peel the tape and press the film on from the top, then the sides, then the bottom, keeping it loose. Wrinkles at this stage are expected.
- 4Shrink with a hair dryer on high, held a few inches off, moving constantly. Work from the middle outward. The wrinkles pull out in seconds.
- 5Trim the excess with a sharp blade held flat against the tape line.
- 6Check the whole perimeter with a lit incense stick. Any smoke movement means an unsealed section, and one unsealed corner undoes the whole window.
Questions people actually ask
- Do window insulation kits actually work?
- Yes, on single-pane and old double-pane windows, because the trapped still air between film and glass is a genuine insulating layer. The effect is much smaller on a modern sealed unit, which already has one. They only work if the tape seal is continuous — a gap anywhere means circulating air rather than still air.
- What is the best window insulation kit for winter?
- For a normal household, a standard shrink-film kit sized to your actual window area. For a house with pets or small children, the heavy-duty puncture-resistant film, because standard film will not survive contact. For a whole house, a rolled kit is cheaper per window and handles odd shapes.
- Will window film damage my paint when I remove it?
- It can, on soft or old paint. Test a short length of the tape in a corner first, and remove it slowly at a shallow angle rather than pulling it straight out. A hair dryer on the tape softens the adhesive and makes removal much safer.
- Can I open the window with film on it?
- No. Sealing the window shut is how the kit works. Leave one window per room unfilmed if you need ventilation, and never film a designated emergency egress window.
- How long does window film last?
- One heating season is the design life, and most people remove it in spring. Heavy-duty film often survives being taken down and is sometimes reused, but the mounting tape is single-use every time.
Sources
- Duck Brand — window insulation kit range and published coverage
- 3M — published five-window indoor insulator kit contents
Every specification on this page traces to a published manufacturer or retailer listing. Where a maker publishes no working gap range, we say so rather than estimating one.
Read next
How to seal windows for winter from the inside
The order of work that stops you filming over a leak you could have closed for free.
Does window insulation film actually work?
Yes on single glazing, much less on modern units, and not at all with a gap in the tape. The mechanism, explained.
Window film or thermal curtains?
One seals the air path, one covers the surface. Which symptom you have decides which you buy.