Formula Used
The main throw formula is:
Throw Distance = Screen Width × Throw Ratio
Screen width comes from the diagonal and aspect ratio:
Screen Width = Diagonal × Aspect Width ÷ √(Aspect Width² + Aspect Height²)
Screen height uses the same diagonal relationship. Lens height is estimated with screen bottom height, half screen height, vertical offset, and lens shift.
How to Use This Calculator
Enter the projector model name for your record. Add the screen diagonal and choose the screen unit. Select a common aspect ratio or use custom values. Enter the minimum and maximum throw ratios from the Epson model sheet. Add optional construction values, such as room depth, projector body depth, rear clearance, mounting height, lens shift, and vertical offset. Press the calculate button. The result appears above the form and below the header. Use the CSV or PDF button to save the calculation.
Example Data Table
| Screen Diagonal |
Aspect Ratio |
Min Throw |
Max Throw |
Approximate Distance Range |
| 100 in |
16:9 |
1.30 |
2.10 |
9.44 ft to 15.25 ft |
| 120 in |
16:9 |
1.30 |
2.10 |
11.33 ft to 18.30 ft |
| 150 in |
16:9 |
1.30 |
2.10 |
14.16 ft to 22.88 ft |
Planning Projector Distance
A projector distance plan protects the room layout before framing starts. Epson models use a throw ratio to describe how far the lens sits from the screen for each unit of image width. That value changes by model and zoom setting. This calculator lets you enter the throw range from your chosen unit. It then converts the screen diagonal into real width and height. The result shows the closest lens distance, farthest lens distance, and a balanced midpoint.
Construction Use
Projection planning is not only an audio visual task. It affects ceiling blocking, conduit paths, power outlets, wall plates, soffits, and service access. A small distance error can place the mount behind a beam or too close to a light fitting. During construction, use the minimum and maximum throw distances as a safe zone. The projector lens must land inside that zone. The mount body, cable bend, and service clearance also need space.
Screen Geometry
The screen diagonal is familiar, yet throw distance depends on image width. A 120 inch diagonal screen in a 16:9 layout is wider than a 120 inch screen in 4:3 format. That is why the calculator asks for aspect ratio. Custom values help when the screen is not standard. The calculator computes width and height from the diagonal before applying throw ratio.
Lens Height
Vertical offset and lens shift help place the projector correctly. Offset moves the lens above or below the screen center. Lens shift adds an adjustable range. This calculator estimates the lens center height from the screen bottom height, image height, offset, and shift. Use that range to coordinate ceiling drops, mounts, and obstructions.
Best Practice
Always verify the final number with the exact Epson model sheet. Measure from the lens, not the case. Keep the lens square to the screen when possible. Avoid relying on digital keystone for permanent installs. It can reduce image quality and waste pixels. Use the export buttons to save the calculation for site notes, client approval, or installer handoff. Record room depth early. Check door swings, speaker locations, sprinkler heads, and ceiling fans. Leave access for filters and lamp service where applicable. Recheck dimensions after finished wall surfaces are fully installed.
FAQs
1. What is projector throw ratio?
Throw ratio is the lens distance divided by image width. A throw ratio of 1.50 means the lens sits 1.50 units away for every 1 unit of screen width.
2. Should I measure from the wall or lens?
Measure from the projector lens to the screen surface. The case depth and mount location are separate construction checks.
3. Can this work for any Epson projector?
Yes, if you enter the correct throw ratio range from the exact model documentation. Different Epson models can have very different lens ranges.
4. Why does aspect ratio matter?
Throw distance uses screen width, not diagonal alone. Different aspect ratios create different widths from the same diagonal size.
5. What is the midpoint distance?
The midpoint is the average of the minimum and maximum lens distances. It gives a balanced planning value inside the zoom range.
6. What does vertical offset mean?
Vertical offset estimates how far the lens center sits above or below the screen center. It helps plan ceiling height and mount drop.
7. Does lens shift replace proper mounting?
No. Lens shift helps fine tune placement. The mount should still be planned carefully, square to the screen, and inside the throw range.
8. Is keystone correction recommended?
Use physical alignment first. Keystone correction can help minor issues, but heavy correction may reduce sharpness and usable image quality.