So, normally I get the concentrated WM brand of bleach that is rated at 8.25%. Our WalMarts recently started carrying 10% bleach in the pool section. Normally I'm dubious of the supplies in the pool section, knowing they are marked up to the unwary shopper. The bottle was $ 3.64 compared to $2.57. So, I did the math.
The 8.25% comes in 121 oz at $2.57 a bottle. 121 x .0825 = 9.99 oz available chlorine. $2.57 / 9.99oz = 26 cents per oz.
The 10% comes in 128 oz, so 128 x .10 = 12.80 oz of available chlorine. $3.64 / 12.80 oz = 29 cents per oz.
So today, the 8.25 bottle wins out, but that price was a rollback, it has been going for $2.98, which ups your unit price to 30 cents.
The difference is pretty negligible, so it's a matter of preference. Do you want to save a couple cents per bottle, or use less product and a few less bottles in your supply closet? I went with 4 bottles of 10%. Of course, this all presumes the label is accurate, both the strength of the bleach, and the amount in the bottle.