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Projector Throw Distance Calculator

Find projector distance or possible screen size using your screen dimensions and the manufacturer’s throw ratio.

Your measurements

Use the manufacturer’s throw ratio for your lens and zoom configuration. Throw ratio is distance divided by image width—not diagonal.

Measurements and calculations stay in this browser tab. Refreshing clears entries. Feedback does not automatically include your inputs or results.

Projector distance

Enter a measurement and throw ratio to see your results.

How it works

  1. Choose screen diagonal, projector distance, or screen width as your starting measurement.
  2. Choose units and enter the measurement. Feet use decimals: 10 feet 6 inches is 10.5 feet.
  3. For diagonal or distance mode, choose the image aspect ratio or enter a custom width:height ratio.
  4. Enter a single throw ratio or its minimum and maximum. Review the calculated range and confirm placement against your installation manual.

A real example

Fictional installation example: an image 100 inches wide and a throw ratio range of 1.15–1.50 gives a projector distance of 115–150 inches (9 feet 7 inches to 12 feet 6 inches). At 16:9, that image has a diagonal of about 114.7 inches.

Working the other way: at a distance of 120 inches, a 1.20–1.50 throw range allows image widths of 80–100 inches. At 16:9, the corresponding diagonals are about 91.8–114.7 inches.

Throw ratio uses image width

Throw ratio = throw distance ÷ image width. Distance = image width × throw ratio; image width = distance ÷ throw ratio. Diagonal mode first converts the image diagonal to width using the selected aspect ratio.

A larger throw ratio means a greater distance for the same image width. At a fixed distance, the maximum throw ratio produces the smallest image, while the minimum produces the largest. Calculations keep full precision; displayed measurements round to one decimal place.

Confirm the actual installation

Use the ratio published for your projector and installed lens, including its zoom range. Check how the manufacturer defines the distance measurement and allow for the projector body, mounting position and installation requirements. Lens shift, offset and ultra-short-throw placement may need additional manufacturer-specific measurements that this simple width-based calculation does not model.

The diagram is explanatory, not a mounting drawing. This tool does not select a projector, calculate brightness or recommend a viewing distance.

Frequently asked questions

Where do I find the throw ratio?

Look in the projector or lens specifications and installation manual. Enter the published single value or minimum–maximum range; this tool does not contain a projector database.

Is screen diagonal the same as image width?

No. Diagonal runs corner to corner. Choose diagonal mode and the correct aspect ratio to calculate width, or use screen width mode when you already know the projected image width.

Can I calculate screen size from a fixed projector position?

Yes. Choose Distance → screen size, enter the distance, aspect ratio and throw ratio. A ratio range gives minimum and maximum image width, height and diagonal.

Can I use inches, feet, centimeters or meters?

Yes. Unit changes convert the current measurement through canonical inches without rounding intermediate calculations. Feet are entered as decimals.

Does this guarantee the mounting position?

No. Actual placement can vary with manufacturer measurement conventions, zoom/lens configuration, offset and installation requirements. Confirm all dimensions with the installation manual before mounting.

Are my measurements uploaded or saved?

Calculations run locally in your browser tab. Measurements are not uploaded or saved by this calculator, and refreshing clears them. Feedback does not automatically include inputs or results.

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