Find a formula for finding the step between values?

Question

Mathematics

Hello. I'm building a chart. We need a formula that, based on the minimum and maximum values, sets the interval (step) between readings. That is, let's say that max=95; min=8; the interval in this case, approximately, should be about ~5. Or max=672; min=35; the interval in this case, approximately, should be ~50. Thank you in advance.

Answer 1

function calcStep($min, $max, $maxStepsQty=7) {
    return ceil(($max-$min)/$maxStepsQty);
}

Answer 2

if ($maxValue/25<=25) $d=5; else $d=50;