FitBit Math - Can I Haz Ur Help?

IdLikeToLoseItLoseIt

Math is not my strong suit and I'm stuck. I want to predict how many additional calories I would burn if I increase my steps. I thought it would be a straightforward linear increase, but it's not. Here are my numbers in an excel screenshot.

What do I do next? I tried dividing this and that, but none of the numbers made sense or worked, so I'm doing it wrong.

Explain like I'm five!

IdLikeToLoseItLoseIt

My "Calories Burned" are my actual burns where my steps were very close to those round, pretty numbers.

lorrpb

Well you don't say your weight. I don't have time to figure out your spreadsheet but for 150 lb person it's about 25 calories per 1,000 steps.