What is throw distance on a projector?

Throw distance and throw ratio, defined

Throw distance is the physical space between the projector's lens and the screen; throw ratio is the formula, distance divided by image width, that a manufacturer uses to tell you what that distance needs to be.

Shopping for a specific model? See the best projectors we tested — 10 models compared on the specs that decide it.

Epson's own projector guide describes throw distance simply as the distance between the projector and the image on the screen, the space the image is thrown across. It sounds obvious until you're standing in a room trying to work out whether a projector will actually fit the depth you have between the back wall and the screen.

Throw ratio is the number that turns that question into arithmetic. BenQ defines it as the width of the image in relation to the throw distance, expressed as distance divided by width. A throw ratio of 2.0 means the projector needs 2 feet of distance for every 1 foot of image width; aim for a 100-inch-wide image and a 2.0-ratio projector needs roughly 200 inches, about 16-17 feet, of clearance behind it. Most consumer projectors publish either a fixed ratio or a range, since zoom lenses shift the number as you adjust them.

Short throw, ultra-short throw, and long throw, compared

Short throw covers roughly 3 to 8 feet from screen to lens, ultra-short throw covers 0 to 4 feet, and long throw (standard) projectors need more distance behind them to hit the same image size, per Epson's published ranges.

Epson's guide splits projectors into three practical categories. Short-throw units generally cover a distance of 3 to 8 feet from projector to screen, useful when a projector has to sit close to the wall without a huge image being demanded of it. Ultra-short throw goes further, into the 0-to-4-foot range, letting a projector sit essentially right up against a low table or shelf below the screen and still fill it.

Long throw is the older, more familiar setup: a projector mounted farther back, often from a ceiling mount in the middle of the room, throwing the image across more open space to reach the same size. The cleaner way to compare the categories is by throw ratio rather than a single fixed distance, since the required distance always scales with the image width you're aiming for. A short-throw unit carries a lower throw ratio and needs less room per foot of image; a standard, or long, throw model carries a higher ratio and needs proportionally more. Both are just different points on the same trade-off between how close a projector sits and how big the image gets.

How to calculate projector throw distance

Multiply the projector's stated throw ratio by your desired image width to get the required throw distance, or divide the available distance by the throw ratio to see what image width fits.

The math BenQ publishes runs in either direction depending on which number you already have. If you know the image width you want and the projector's throw ratio, multiply the two: a projector with a 1.5 throw ratio aimed at a 100-inch-wide image needs about 150 inches, roughly 12.5 feet, of distance. If you already know how much distance your room allows, divide that figure by the throw ratio instead to find out what image width actually fits.

Zoom lenses complicate this slightly, since a projector with adjustable zoom lists two throw ratios, one for its widest setting and one for its narrowest, rather than a single fixed number. Manufacturers commonly publish these figures as a chart or an online calculator rather than making buyers do the multiplication by hand, and it's worth running your own room's numbers through one before ordering rather than trusting a listing photo that shows a large, inviting image with no distance noted.

Checking a spec sheet against your room

Consumer projector listings often state a projection-distance range directly, and matching that range to your actual room depth avoids ending up with an image that's too small or doesn't fit the wall at all.

Plenty of consumer projectors skip the throw-ratio math entirely and just publish a projection-distance range alongside an image-size range, which is arguably more useful for a quick gut check. The feed-listed Pericat outdoor projector is a good example: it states a 4.1-17.5ft projection distance across a 35-to-200-inch display range at 50-100% zoom. Read literally, that means the same unit can sit anywhere from about 4 feet to nearly 18 feet from the screen, producing a bigger image the farther back it goes.

That range is worth measuring your own room against before buying, not after. A projector with a listed minimum distance longer than your actual room depth will never fit a usable image on the wall no matter how the zoom is adjusted; one with a shorter minimum than you need just means you have flexibility to sit it closer than the ceiling-mount photos in the listing suggest. Either way, the spec sheet number matters more than the marketing image next to it.

Short throw vs long throw: which one fits your space

Short-throw and ultra-short-throw projectors suit smaller rooms or setups where the unit has to sit close to the wall without anyone walking through the beam; long-throw projectors suit larger rooms with the depth to spare and are the more common ceiling-mount setup.

The practical decision usually comes down to room depth and where people walk. A short-throw or ultra-short-throw projector, sitting close to the screen on a low shelf or table, keeps the light path close to the wall, which matters in a smaller living room or bedroom where someone crossing the room would otherwise cast a shadow across a long-throw projector's beam. It's also the more forgiving choice when there simply isn't much distance between the far wall and the screen to work with.

A long-throw projector needs the opposite: real distance behind it, which is why the classic ceiling-mount setup in a dedicated home theater or larger living room is almost always a standard-throw unit rather than a short-throw one. Neither is objectively better; they solve for different room shapes. Our projectors hub compares models across both categories, and our portable projector picks lean toward compact, flexible-placement units where short-to-medium throw ranges tend to matter more than in a fixed, dedicated room.

Throw distance for mini and pocket projectors

Mini and pico projectors trade brightness and native resolution for size, and their throw-distance ranges tend to be shorter and more casual, suited to close-range, informal viewing rather than a large, dedicated screen.

Mini and pico projectors add a wrinkle to the throw-distance question because they're rarely bought for a precisely measured home-theater setup in the first place. The feed-listed KODAK Luma 150, for instance, weighs about 7.5 ounces and outputs 55 ANSI lumens at a native 640x360 resolution, specs built around close-range, casual, or travel use rather than filling a large wall from across a room. A projector in that class is generally used propped on a nightstand or table a few feet from a wall or portable screen, not measured against a throw-ratio chart the way a home-theater installation would be.

That's a fair trade for the format: a device this small isn't trying to compete with a ceiling-mounted long-throw unit on image size, and its practical throw distance is more about what fits comfortably on the surface nearby than a formula. Our mini projector picks are worth a look if pocketable size matters more to you than throw-distance flexibility or a large maximum image.