Formula
Pixel pitch is the diagonal divided by the pixel diagonal. Distance divides that pitch by the tangent of one arcminute:
distance = (diagonal / √(width² + height²)) / tan(1′)
One arcminute is 1/60 of a degree. The PPI page stops at pixels per inch and does not choose a chair.
Assumptions
- The acuity target is one arcminute.
- The diagonal is the image area in inches.
- Pixels are square, so one pitch describes both axes.
Worked example
A 1920 by 1080 screen of 24 inches reaches one-arcminute pixels at 37.45 in.
Input definitions
- Arcminute
- One sixtieth of a degree. Standard visual acuity separates details of about that size.
- Acuity distance
- How far from the screen that angular size matches one pixel.
Limitations
This is a planning figure from the numbers you type. It is not a measurement of a network, a camera, a printer, or a power supply.
Questions
Is this a recommended TV distance?
It is the distance where pixels merge for one-arcminute acuity. A viewing habit can be closer or farther on purpose.
What does the PPI page answer instead?
How many pixels fit in an inch. It does not divide by an angle.