how many times do you bleach black hair to be blonde?

You'll have to bleach it a lot.

And for long periods of time.

Even if you have healthy hair it will damage it so much bleaching it that much in that short amount of time it's not even worth doing it. There is not possible way to have healthy bleached hair.

I don't suggest doing it within a week.

I would bleach it, then deep condition every day for a week then do that weekly until your hair gets to the color you want.

I went from dark brown hair to blonde very gradually. start with all around high light and add every few months as the roots come in and when you think you are ready bleach all your hair to turn blonde. My hair grow really fast so I decided to go back to brown recently. My hair grows like an inch every 2 months so it was hard and expensive to keep up.

also you may need a toner with violet under tones to get the orangish color out, cuz likely your hair will not be all blonde cuz your hair is dark. Also buy some violet shampoo. and skip shampooing too because your hair will be dry from the processing.

I dyed my hair in 7th to the middle of 8th grade. It turned out orange when I went blonde too. But after going three times to get back my golden hair, It worked. Back to normal. It might take you four times to get the color you want. Maybe 3. But don't go until after 2-3 months for each so your hair doesn't damage a whole lot.

I stripped my hair of color years ago when I wanted to go from dark reddish brown to reddish blonde. You can buy it in a drug store and then buy the blonde dye and apply it in accordance with the directions.

ew...and why would you want to change it to blonde?