[LonePalm]

With the "%" gives you five times the width of the picture.

Without the "%" gives you 500 pixels.

SpyNavy

Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)

[Bob Ireland]

***With the "%" gives you five times the width of the picture. Without the "%" gives you 500 pixels***

Ah... Well, if greywhiskers had used 500% on that graphic I would have had to knock a wall down out of my house to display it! ❗

[numberonepal]

Here’s my basic rules of thumb.

If original image width is less that 600px do not use the width attribute.

If the original image can be reasonably communicated AT width=600, use it. 600px is optimal viewing for phone phags and desktop phags.

The max I will ever make an image is 810. Anything wider than that starts to get to side scroll on some accessible and low rez screens.

If the image cannot be communicated at 810, set width to 810 and link it to the larger original.

Bonus: if you have a long image with a short width I like to set a 420 so you can see the whole image without scroll.

I go way back on FR and these guidelines have served me well. There was a time when you had to be conscientious about file size and such.