Projector throw distance, explained without the jargon

Projector throw distance, explained without the jargon

Most projector returns happen because the buyer measured the room wrong, not because the projector was bad. The picture came up too small, the shadows were awful, or the mount point landed somewhere the swing would eventually destroy. Every one of those problems is a throw distance problem, and throw distance is one multiplication problem.

Throw ratio is the only spec you need to understand. Everything else on the spec sheet is detail.

The one number that matters

Throw ratio is the distance from the lens to the screen, divided by the width of the picture. That is it. A throw ratio of 0.7 means the lens sits 0.7 feet back for every foot of picture width. So:

• A 10 foot wide picture with a 0.7 ratio: the lens goes 7 feet from the screen.
• A 12 foot wide picture with a 0.5 ratio: the lens goes 6 feet from the screen.

The formula is throw distance = throw ratio x image width. Tape measure in one hand, calculator in the other, and you know exactly where any projector can go in your room before you buy it.

One catch that burns people: the ratio multiplies the picture width, not the screen's diagonal. Screens are sold by diagonal. Measure the horizontal width of the image you want to project, not the diagonal number on the box.

Short-throw vs standard: when each one wins

Projector people sort ratios into bands, roughly:

• Ultra-short-throw: below about 0.4. Sits inches from the screen, on the floor.
• Short-throw: about 0.5 to 0.9. The golf simulator default.
• Standard: 1.0 and up. Home theater territory, needs a deep room.

Standard projectors lose in most sim rooms for one reason: math. A 1.5 ratio on a 12 foot wide picture needs 18 feet of throw. That puts the lens in the middle of your swing space, or behind the back wall. Short-throw projectors exist because sim rooms are not home theaters.

Our take: if you are buying a projector specifically for a simulator, buy short-throw and move on. The debate is which short-throw, not whether.

A real example: the BenQ LH820ST has a 0.497 throw ratio. On a 10 foot wide picture, it sits about 5 feet from the screen. That leaves the whole room behind it for swinging. It is $1,899 as of Oct 15, 2026; check our LH820ST deal page for the live price.

Ceiling mount vs floor: the shadow question

Where you put the projector matters as much as which one you buy. Two options.

Ceiling mounting is the default for a reason. The safest spot, according to builders who have done this hundreds of times, is on the ceiling directly over the tee, slightly behind the ball. None of them report hitting it. Being overhead puts the beam above your swing, and sitting close to the screen keeps your body mostly out of the beam.

Floor mounting works, but only with the right ratio. A ratio around 0.5 lets the unit sit close to the screen on a low table, safely in front of the swing. The catch is vertical offset: where the image lands relative to the lens. A projector built for a coffee table throws its image upward, so check the offset in the manual before you commit, or the picture lands on the ceiling.

The shadow rule, stated once: shadows are a distance problem, not a brightness problem. The farther back the lens, the more of your body is in the beam. A short-throw on the ceiling casts far less shadow than a standard-throw mounted on the back wall. That is the real reason sim builders default to short-throw, not image quality. This mounting guide from My Golf Simulator walks through the placement logic with example setups.

The three measurements to take before you buy

Do these with a tape measure, not guesses. It takes ten minutes.

1. Picture width. Decide how wide the image will be, usually the width of your impact screen. Write the number down in feet. This is the number the ratio multiplies.

2. Mounting distance. Measure from the screen to the spot over your tee, slightly behind where the ball sits. That is your throw distance budget. Multiply your picture width by each candidate projector's throw ratio. If the answer lands in your mounting zone, the projector fits. If it lands in your swing path or behind the wall, cross it off.

3. Ceiling height and obstructions. The mount point has to actually exist. Check for garage door tracks, lights, beams, and low ductwork. Then note the ceiling height against the projector's vertical offset spec, which says where the image lands relative to the lens. High offset means the lens can sit flush to the ceiling. Low offset means the mount drops the projector down, or the picture lands too high.

One safety rule worth stealing from projector builders: subtract your hitting zone depth from the throw distance and keep at least 2 feet between your swing arc and the lens. More is better. The Treasure Valley Solutions projector guide lays out this clearance check with example room math.

A worked example, start to finish

Say your screen is 10 feet wide, your room is 18 feet deep, and your tee sits 10 feet from the screen. The spot over the tee is 10 feet from the screen. That is your throw budget, minus a little for the mount.

• A 0.7 short-throw projector: 0.7 x 10 = 7 feet. Mounts 7 feet from the screen, 3 feet in front of the tee. Fits, with room to spare.
• A 1.5 standard projector: 1.5 x 10 = 15 feet. That is 5 feet behind your tee, inside your backswing. Does not fit.
• The LH820ST at 0.497: 0.497 x 10 = about 5 feet. Sits 5 feet from the screen, far from everything.

That is the whole skill. You will never again wonder if a projector "works with" your room.

Our take

Buyers research lumens, resolution, and input lag for hours, then mount the projector wherever the ceiling joist happens to be. That is backwards. When we wrote about 4K vs 1080p projectors, the conclusion was that brightness and placement beat resolution. Throw distance is the placement half of that advice, and it is the half you can get exactly right for free, before you spend anything.

Learn the ratio. Take the three measurements. Then buy the projector that fits the room you have, not the room you wish you had.