How to determine what size spokes my wheel uses?

[Kriegsspiel]

So... I broke a spoke
and now, to get the right size
What do I measure?

[Russ]

easiest / maybe less accurate: measure a spoke you already have. The one you broke if you have both halves and it's not stretched too much, or one on the bike if that would be easier. Measure from the inside of the shoulder to the end of the threads. Make sure if you measure on the bike that you pick a spoke from the same side as the broken one. Drive side spokes are about 2mm shorter than non drive side in the rear wheel.

more difficult / maybe more accurate: spoke length calculator. Enter your info in the drop-down menus and it will populate the numbers for you, or fill them in yourself

Nearly everything you'll ever need to know about wheelbuilding: http://sheldonbrown.com/wheelbuild.html

[GuitarStv]

Even easier way to get the right spoke/nipple size . . .

Go to your bike shop with the wheel and ask for a spoke that fits.

[projekt]

If you are replacing a spoke, you will need a wheel truing station and possibly a dishing tool, a spoke wrench, and the means to get at the hub if it is a rear wheel. This investment pays for itself, even if your bike shop has reasonable prices.