Smartphone Projector Calculator
Compute setup geometry using thin-lens optics and desired screen size.
How to Use This Calculator
1
Enter your phone screen size
Use diagonal inches (spec sheet). Measure if unsure.
2
Choose desired screen size
Bigger screens require longer throw distance or longer focal length.
3
Enter lens focal length
Typical magnifying glass lenses are 50–100 mm. Shorter f gives shorter distances.
Formula
M = v/u, 1/f = 1/u + 1/v → v = f(1+M), u = f(1+M)/M
M is magnification (image/object diagonal). u is lens→phone, v is lens→screen.
Frequently Asked Questions
Will the image be inverted?
Yes. You need to flip the phone’s image (or use a mirror pair) to correct orientation.
Does brightness depend on lens?
Brightness mainly depends on phone luminance and screen size; larger images look dimmer.