Smartphone Projector Calculator

Your details

Choose which measurement you want to calculate. The other two must be provided.
The focal length printed on your magnifying lens, or measure it by focusing sunlight to a point and measuring the distance to that point.
mm
Distance from the centre of your phone screen to the centre of the lens. Must be greater than the focal length for a real image to form.
mm
The physical height of your phone display (the shorter dimension of the active screen area, not the diagonal). Measure with a ruler for accuracy.
mm
Solved distancePractical magnification
1,275

The distance calculated from the other two inputs

Magnification7.5
Projected image height487.5
Total throw distance1,445
Unit labelmm
7.5 x
Too small<2Practical2-8High - dark room needed8-12Too dim12+

Magnification is 7.50x - a usable projection setup.

  • The calculated lens-to-screen distance is 1275.0 mm.
  • Your projected image height will be approximately 487.5 mm (48.7 cm).
  • Total throw distance from phone to screen is 1445.0 mm.
  • Brightness is significantly reduced at this magnification. A dark room will give the clearest image.

Next stepThe image will appear inverted. Rotate your phone 180 degrees and flip your screen orientation (or use the developer rotation lock) to correct it.

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