I have light brown hair, not super light but not dark brown. Do I need 30 vol developer or 40?

It all depends on what color you're going to.

If you're going just a few shades, then 20 will be fine.

If you go to a dirty blonde, then 30 will be fine, but if you're going to a brighter blonde, then you'll need 40.

You have to be careful though, cause you're hair can get seriously damaged and break off, leaving you bald in some spots.

If you're doing anything too drastic, then go to a salon.

Oh, and if you're going darker, then again, 20 for a few shades, and 30 or 40 for anything super dark. And you'll also want 30 for any red or purple tinted colors.

Hope I helped, good luck! (:

that must be undesirable on your hair, even with severe carry that blue will possibly no longer carry from the hair in basic terms yet, including a mild blonde beige dye wont do something after that, because of the fact my hair became like that i had to dye it 4 circumstances with bleach just to get pink out of my hair, it went an quite orange/ carrot seem. wasn't too spectacular on the attention lmaoo.. i might propose seeing a hairdresser, reason years later my hair is feeling the after impacts, very dry, bristle yet its what it takes to grow to be a blondie!

unfortunately i think it depends! things like the condition of you hair come into play... always test the product before using it too as you could ruin your hair