Question 1

What is 1500x500 used for?

Accepted Answer

1500×500 is the X header size, used for X and Twitter profile headers. Matching it exactly avoids the platform cropping or re-compressing your image in a way you did not choose.

Question 2

How do I resize an image to 1500x500 without stretching it?

Accepted Answer

Crop to the right shape first, then scale. Scaling a differently-proportioned image straight to 1500×500 distorts it; cropping to 3.00:1 first and then scaling keeps everything in proportion.

Resize to 1500 × 500