I would like to create a landing page header,footer and email to upload as an image. what is the best size?

Can you give us more information?

Is this a footer image for a landing page and also an email template?

I think the optimal size is for a 600px email and maybe 800px LP, but do a web search to confirm.

600 is possible, but better is to use 550 max. However this will give you some headaches when you want to use @media queries to make your templates mobile friendly (use 300 as width).

For a landing page, I recommend using an image of 960 px. For email, 550 px is best and you can use media queries to design a responsive mailer.

Hi Alok, of course you can use @media queries to resize the image. Although this might effect the image quality.