Best way to tell if a knife is sharp?

[timbit]

For kitchen knives, an excellent test is to try slicing a ripe tomato. If you can make thin slices on thin-skinned tomatoes, the knife is quite sharp for kitchen use.
Faiaoga

My kitchen knife test is rapid chopping (not slicing) of tomatoes. If I can push-cut chop ripe tomatoes with little resistance on the skin...its sharp enough.

[video=youtube;QtTXwqp6BAE]http://www.youtube.com/watch?v=QtTXwqp6BAE[/video]

 

[kenstogie]

dullknifeterminator I didn't know you were a member here I bought an edge pro from you 2 weeks ago thank you for the fast shipping . Good business man Wish I would of known you were on the forums.

Ditto here. I like the EP but need more practice to get my edges really sharp.

 

[Shotgun]

By touch, using my thumb, or if it will pop hair. Another way I rarely use is, when I cut myself and don't notice until I see the blood.

I stropped a D Farmer knife and then went to making fuzz sticks. I sliced through my finger NAIL without feeling it. The sharpest I've ever made a knife.

 

[dark impaler]

If I can cleanly slice a sheet of paper through it's entire blade edge, then it's good to go.