How do I calculate pixels number

[Telushomey]

Adults need 2.5" between Eyes, but this is too far for kids eyes.
Adults = 2.5" = 52 Pixels difference = left eye 26 pixels, Right eye 26 pixels
Kids = 2.0" = ? Pixels = Left eye ? Pixels = Right eye ? Pixels (less than 26 each eye is all I know)

This is to calculate the parallax in 3D video. I need to know how much pixels kids use, and all I know is it's less than the 52 pixels for Adults eyes.

 

[Mark44]

Adults need 2.5" between Eyes, but this is too far for kids eyes.
Adults = 2.5" = 52 Pixels difference = left eye 26 pixels, Right eye 26 pixels
Kids = 2.0" = ? Pixels = Left eye ? Pixels = Right eye ? Pixels (less than 26 each eye is all I know)

I have no idea what you're trying to say here.

This is to calculate the parallax in 3D video. I need to know how much pixels kids use, and all I know is it's less than the 52 pixels for Adults eyes.

??

 

[Telushomey]

So 2.5" is equivalent to 52 Pixels, or 52 pixels = 2.5" inches difference.
52 Pixels = 26 Pixels * 2 (26 pixels each eye)

I need to know how many pixels if the inches used is 2.0 inches difference, not 2.5 inches.
I think I need to use division but don't know how.

 

[Mark44]

Use a proportion. 2.5/2.0 = 52/x

What kind of a screen is this you're working with? ~20 pixels/inch seems very low resolution to me.

 

[Telushomey]

Use a proportion. 2.5/2.0 = 52/x

What kind of a screen is this you're working with? ~20 pixels/inch seems very low resolution to me.

It's not resolution, it's for cropping to make parallax either negative or positive.

Maybe this is the way?

2.5 / 2.0 = 1.25
52*1.25 =65
65 - 52 = 13
52 - 13 = 39
38 / 2 = 19 pixels difference each eye.

Thank you Mark44!