Here's an even easier way (and it works!)

Get a measured eye-dropper at a drug store--one that measures from .2 ml up to 1.0 ml--they sell them, I have one. Get a glass one just to be safe.

Fill up an empty 2liter soda bottle with tap water to the same level they fill it with soda.

Use the eyedropper to add .2 ml of the LC or bleach you are testing to the soda bottle. Cap and shake.

Now measure the chlorine level of the soda bottle just like it was a pool. That number will be the concentration of your liquid chlorine. I tested my "12%" from a car-boy and it tested at 14%.

Don't forget to test your tap water first as Chem_Geek said and subtract that number from your total.