What throw ratio means
BenQ defines it simply: throw ratio is "the distance from projector to screen divided by the width of the image."
So:
- Throw ratio = throw distance ÷ image width
- Throw distance = throw ratio × image width
A 0.5 throw ratio means that for every 1 foot of image width, the projector sits about 0.5 feet from the screen. A 0.8 ratio needs more room for the same picture.
BenQ also points out a catch. Spec sheets assume you use the projector's full native width. Many home sims do not.
Why golf sims use short-throw projectors
BenQ says short-throw projectors "can be mounted above and behind the hitting area" so the golfer does not cast a shadow on the screen. Its golf FAQ says "the safest place to mount the projector is on the target line," and that to avoid shadows you should place the projector "no more than 3–4 feet behind the player."
BenQ's FAQ also names ball strikes as a concern. It says about 7–8 feet from the screen is far enough away to avoid a ball hitting the projector. BenQ calls a short throw "between 0.69 and 0.89" the sweet spot for most setups. For tight rooms it says a ratio around 0.5 may be needed.
Optoma's golf sim page makes the same point in general terms. It says its short-throw models range from about 0.5 to 0.9 and help with "reducing shadows and maximizing the hitting area."
The 16:9 projector, 4:3 screen problem
Most golf projectors are natively 16:9. Many golf screens are closer to 4:3 because a taller image gives more swing room. BenQ's golf FAQ recommends a native 16:9 or 16:10 projector, then sizing the image to 4:3.
When you do that, the projector still throws its full 16:9 width. The sides of that width go unused. That unused strip is why your throw distance comes out longer than if you used your screen width.
BenQ gives a formula for this case:
- 16:9 projector showing 4:3: throw ratio = (throw distance × 0.5625) ÷ image height
- 16:10 projector showing 4:3: throw ratio = (throw distance × 0.6277) ÷ image height
Worked example
Say your screen shows a 4:3 image that is 10 feet wide and 7.5 feet tall. You have a 16:9 projector with a 0.499 throw ratio (the AH500ST's stated spec).
Step 1. Find the projector's full 16:9 width at that height. 7.5 ÷ 0.5625 = 13.33 feet.
Step 2. Multiply by the throw ratio. 0.499 × 13.33 = about 6.65 feet.
So the lens sits about 6.7 feet from the screen. If you had wrongly used the 10-foot screen width, you would get 0.499 × 10 = 4.99 feet. That is almost 2 feet too close, and the image would not fill the screen height.
Same screen, other ratios (our math):
- 0.69 ratio: 0.69 × 13.33 = about 9.2 feet
- 0.83 ratio: 0.83 × 13.33 = about 11.1 feet
- 0.89 ratio: 0.89 × 13.33 = about 11.9 feet
Zoom, lens shift, and keystone
Zoom gives you a range of throw ratios instead of one number. The AK700ST lists 1.2x zoom and a 0.69–0.83 ratio. On the screen above, that is roughly 9.2 to 11.1 feet. Fixed lenses, like the AH500ST and ZH451ST, give you one distance per image size.
Lens shift moves the image up, down, or sideways without tilting the projector. BenQ's FAQ says you will usually want a short-throw projector with enough vertical and horizontal lens shift. It also notes that lens shift varies by model.
Keystone is digital. BenQ's FAQ says keystone "is a digital process where the projector uses scaling and compression to alter the image," which results in "compromised image clarity." Use mounting position and lens shift first. Treat keystone as a last resort.
A note on ultra-short-throw placement
BenQ notes that with a floor mount, "the whole setup is typically in front of the golfer," and there is a risk of hitting it with a low drive and knocking it out of alignment.
Planning advice from us: any projector that sits on the floor near the screen is in or near the ball's path. If you go that route, plan for ball clearance and protection. If your ceiling allows it, a mount above and behind the hitting area keeps the projector out of play.
Projectors we carry: stated specs
All values come from each maker's own spec page or data sheet.
| Model | Stated throw ratio | Native resolution / aspect | Zoom | Source |
|---|---|---|---|---|
| BenQ AH500ST | 0.499 | 1080p (1920x1080) / 16:9 | Fixed | BenQ spec page |
| BenQ AK700ST | 0.69–0.83 | 4K UHD (3840x2160) / 16:9 | 1.2x | BenQ spec page |
| BenQ LK936ST | 0.81–0.89 | 4K UHD (3840x2160) / 16:9 | 1.1x | BenQ spec page |
| Optoma ZH451ST | 0.49:1 | 1080p (1920x1080) / 16:9 | Fixed | Optoma data sheet |
A few extra notes from the same pages. The LK936ST lists vertical lens shift of -60% to +60% and horizontal of -23% to +23%. The AH500ST and AK700ST spec pages do not list lens shift. The ZH451ST data sheet lists 4:3, 16:9, and 16:10 as compatible aspect ratios.
Check current listings: BenQ AH500ST · BenQ AK700ST · BenQ LK936ST · Optoma ZH451ST on Amazon.
A calculator from BenQ
BenQ Golf Sim-room Planner: BenQ says it "helps calculate projection image size and distance."
How to check your room
- Measure your screen's image area: width and height, in feet.
- Check the shape. If it is 4:3 and your projector is 16:9, divide the height by 0.5625 to get the projector's full image width.
- Multiply that width by the throw ratio. That is your lens-to-screen distance.
- For a zoom lens, run the math at both ends of the range.
- Mark the spot on your ceiling. Check it against where you stand to hit, and against BenQ's shadow and ball-strike guidance above.
- Plug your room into our room-fit builder to see what fits. For depth, width, and ceiling planning, see golf simulator room dimensions.
FAQ
How far should a projector be from a golf screen? Multiply the throw ratio by the projector's full image width. For a 4:3 image 7.5 feet tall from a 16:9 projector with a 0.499 ratio, that is about 6.7 feet.
What throw ratio do I need for a golf simulator? BenQ calls 0.69 to 0.89 the sweet spot for most setups, and says around 0.5 may be needed in tight rooms. Your room depth and screen size decide it.
Is there a throw ratio calculator for golf? Yes. BenQ has a Golf Sim-room Planner, linked above.
Can I use a 16:9 projector on a 4:3 golf screen? Yes. BenQ recommends a native 16:9 or 16:10 projector sized to 4:3. Just use the full 16:9 width in your distance math.
Is keystone correction bad for a golf sim? BenQ says keystone is a digital process that compromises image clarity. Lens shift and good mounting are better first fixes.
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