 <p>Assuming you want a height in pixels of 500, you can use this to get the intervals:</p> <pre><code>import math pixels = 500 offset = math.log(10) for x in range(10, 71, 10): print x, int(pixels * (math.log(x) - offset) / (math.log(70) - offset)) </code></pre> <p>This is the output:</p> <pre><code>10 0 20 178 30 282 40 356 50 413 60 460 70 500 </code></pre> <p>The pixel counts are just the differences between the start and end of each interval. Change 500 to fit your application.</p>