"garlicman" None wrote in message
. ..
I've got 8 or so white LEDs, but no specs on them. They look average size
with no particular markings. I want to make a small light using a 12V
power source. The online calculators I see ask for their voltage and
current ratings.

How do I determine these numbers?

If you have a variable DC supply (0 to 10 volts or so) and a multimeter,
just connect them with a series resistor of 150 ohms or so and slowly crank
up the DC voltage. Stop when the brightness is adequate or no longer much
increasing and measure the current and voltage drop.