What color scale to use for heat map with positive and negative values?

Question

I am trying to see what the most intuitive or most conventional color scale would be for a heat map with values that can be either positive or negative (percent difference from expected).

e.g., -50%, 0%, 50%

Scales I'm considering are:

• Blue for negative, white for zero, red for positive
• Red for negative, white for zero, green for positive

I think it makes sense for zero to be white because it's important to know that something is neutral in this case.

I like blue-red because positive doesn't necessarily mean good in this case; however, red indicating higher also might feel counter-intuitive.

Answer 1

Red and green are well known for positive and negative values. What is your domain?

Question: What do other companies in your domain do, and what are users trained to expect when interpreting these values?

Either way, be careful with using only color as an indicator. Your pic seems to show the x and y axis values, but the cells are blank. You can indicate change (or the current values) by showing the values inside the cells themselves.