Estimating Cell / Battery Discharge Capacity From Charged Capacity?

Is it possible to estimate the discharge capacity (mAh) of cells and batteries based on their actual fully charged capacities?

If so, How?

Thank you!

I think it was mentioned here before that for good performing (not high resistance old battery) lithium-ion battery, the charged capacity should be almost equal to the discharged capacity (eg. discharged to 2.75-2.80v for most batteries, then charge them to 4.20v; or the other way around fully charged 4.20v then discharge at say 0.5A or 1.0A to 2.75-2.80v, with ending charging/discharging current of around 0.10A or so)