The Best Window Insulation Kits and Draft Stoppers

A drafty house doesn't announce itself. You just notice that the room with the big window stays cold no matter how high you set the thermostat, or that your feet get chilly on the couch nearest the front door. The Department of Energy estimates that air leaks around windows and doors account for 25 to 30 percent of a home's heating and cooling energy use. Sealing those leaks is cheap, it takes an afternoon, and it's one of the few home upgrades that pays for itself before the season is out.

But let's be honest about what these products can and can't do. Shrink film won't turn a rattly single-pane window into a modern double-pane unit — it roughly doubles the effective R-value at the glass, from about R-1 to R-2, which is real but modest. Most film kits are a one-season affair; you peel them off in spring and buy new ones in fall. Draft stoppers under doors help a lot with the cold-ankles problem, but the ones that don't attach to anything will get shoved around every time the door swings.

The good news is that you don't have to choose. Film on the windows and a seal under the door work on different leaks, and doing both cuts far more infiltration than either alone. We think that the Duck Brand Winter Window Insulation Kit is the best window insulation kit for most people, and that the MAXTID Under Door Draft Stopper is the one to buy if your worst drafts come from under a door rather than around the glass.

Buy one of these if you live with single-pane or old double-pane windows, feel cold air moving near the glass or under a door, and either can't or don't want to replace windows yet. That covers a lot of renters in older buildings, first-time homeowners doing a weekend of weatherization, and anyone in the Midwest, Northeast, or Mountain West watching heating bills climb. Family Handyman estimates a full DIY film-and-foam sealing project can cut heating bills by 5 to 15 percent in homes built before 1980.

You can skip most of this if your windows are recent, tight double- or triple-pane units with intact weatherstripping — film adds little there and you'll notice the haze more than the savings. This guide covers window film kits, magnetic window panels, under-door draft stoppers, and door bottom sweeps. It doesn't cover attic or wall insulation, storm windows, replacement windows, or HVAC work, all of which move the needle more but cost far more too. Consumer Reports notes that drafty windows and doors rank among the top three issues found in professional energy audits, behind attic insulation gaps and HVAC problems — so if you've done this and you're still cold, look up next.

Sealing performance: we favored full-perimeter window tape and dual-layer or dual-sided door seals over anything that blocks only one face of a gap. Damage-free installation: tape, magnets, and friction-fit designs came first, since so many people buying these products rent and can't drill into a door. Fit range: we checked stated widths and gap tolerances against the uneven half-inch to three-quarter-inch clearances typical in pre-1990 interior doors. Indoor vs. outdoor: thicker UV-stabilized film belongs outside and thinner film belongs inside, and we didn't treat those as interchangeable. Cost across seasons: a kit you rebuy every fall and hardware that lasts a decade aren't comparable on sticker price, so we weighed expected lifespan alongside coverage.

If you own the place and want to stop doing this every year: The Frost King A82/36H Extra Wide Heavy Duty ($16.19) — The Frost King A82/36H is a screw-mounted aluminum and vinyl sweep, and it's the permanent answer to a door gap. It's extra wide, sealing gaps up to 1-1/4 inch, with slotted screw holes so you can adjust the height for a tight fit rather than living with wherever the screws land. Fasteners are included and the job takes minutes. Family Handyman puts the expected service life of a screw-mounted aluminum sweep at 5 to 10 years, versus 1 to 3 seasons for adhesive foam. The catches: you're drilling into your door, so this is a homeowner product, and owners note the included screws are weak — plan on swapping in better ones, especially on a metal door. A few units also arrive slightly bent and need coaxing straight.

If you need to cover a window from the outside: The Frost King V95H Extra Large Window Insulation ($11.59) — The Frost King V95H is the only outdoor-rated kit here. It's a single extra-large 62-by-210-inch sheet of 2-mil plastic with cold-weather double-faced mounting tape, and it'll cover one very large window or up to five standard ones. Use it on a garage, a shed, a crawl space vent, or any window you can't reach from inside — indoor-only film and tape will peel off an exterior surface within weeks. It's also fine used indoors on a big picture window. Owner reports on the tape are mixed, though: at least one owner who'd had good luck with a competing outdoor kit found this one letting go during the first hard cold snap. Prep the surface carefully and press the tape down hard.

Here's what else our research turned up. This isn't every window kit and door seal for sale — it's the group we compared against the picks, and each of these lost on a specific point rather than being bad.

The 3M Indoor Window Insulator Kit - Five ($16.48) — The 3M Indoor Window Insulator Kit is the best-known name in this category and covers five 3-by-5-foot windows with a one-year limited warranty against defects. It reduces condensation and frost on the glass, which is the reason a lot of people buy film in the first place. But it lost to the Duck kit on two counts: pre-sized sheets are less flexible than a roll when your windows aren't standard, and owner feedback on the included tape is notably rougher — a recurring theme is the tape not sticking well and the backing tearing during application. It's still a solid kit if you have five standard windows and clean trim, and the brand's adhesive reputation isn't undeserved.

The BAINING Metal Door Draft Stopper ($21.99) — The BAINING door sweep is a 42-inch aluminum strip with two silicone sealing layers and 3M VHB adhesive backing, and it covers gaps up to 1.5 inches. Its real selling point isn't drafts — it's that mice can't chew through metal the way they get through rubber and foam, and owners dealing with critters under an apartment door are its happiest customers. It didn't make a pick because cutting aluminum to size needs a hacksaw or metal shears, which puts it out of reach of a scissors-and-five-minutes install, and owners describe the pre-applied tape as hit or miss. Choose it if you have a pest problem as well as a draft problem.

Almost every failure with these products traces back to surface prep. Before you tape anything, wipe the window trim or door bottom with a dry cloth and let it fully dry — dust and condensation are what make tape release in January. Apply film to a warm surface if you can, and if the room is cold, warm adhesive strips with a hair dryer before pressing them down. When you shrink the film, keep the dryer moving and a few inches off the plastic; holding it in one spot melts a hole. Work from the center out. If a corner does pop loose mid-winter, re-tape it right away rather than waiting, since the flapping edge will pull the rest free. In spring, peel tape off slowly and at a low angle to limit residue on painted trim.

For this guide:

• We compared manufacturer specifications across every kit here, including film thickness, coverage per package, stated door widths and maximum gap tolerances.
• We read published guidance from the Department of Energy, ENERGY STAR, Consumer Reports, Family Handyman, Bob Vila, and The Spruce on weatherization and draft sealing.
• We reviewed themes in owner feedback for each listing, paying particular attention to recurring complaints about tape adhesion, foam durability and fit.
• We read owner reviews on every listing, weighted toward the critical ones, because that is where the recurring failures show up.
• We have a systematic way of automatically fetching the latest prices, so the numbers on this page stay current.
• This is a research-focused guide, so the team may not own every product listed — though we often do own the top winners, which gives us extra context for the recommendations.
• We don't accept free products, and the retailer commission never changes which product we recommend.