For me between waist and upper thigh.

Hold your hammer parallel to the ground with your arm almost straight like at the end of a down stroke. The hammer face should be parallel to the anvil face and your arm should be comfortably extended. Too high or low and the hammer face does not hit the anvil square.

You should be able to stand normally without having to reach to strike the anvil.

Hope this answers your question.

I'm no blacksmith, but I believe I heard that with a hammer in your hand with it's face flat on the anvil your arm should be almost extended down at your side, or perhaps a comfortable bottom of your stroke position. I remember that from when I put my anvil on a stump. I know I left mine a little high at about 30.5" to the face. I replaced a stump my grandfather had it on which was quite a bit shorter. I'd guess he had it at about 28".

I am a professional blacksmith, and one who not too long ago went through a lot of therapy to restore a damaged arm form having my anvil too low. The old advice about having the anvil face at the height of your knuckles when your arm is hanging at your side is dead wrong. That height was the standard recommendation a hundred years ago, when much work was done by strikers wielding sledge hammers and the smith only tapped to show them where to hit.

The motions of swinging a sledge and a hand hammer are totally different. When swinging a hand hammer, you want your hammer face to make contact with the anvil when your arm is less than fully extended. In fact, my therapist advises, your arm should be just a bit past 90 degrees at the elbow joint, and the wrist should be relatively straight. In this position, the tendons of the wrist and elbow are in the best spots to absorb the shock without damage.

I'm about six feet tall and, according to my wife, have long "monkey arms." To me, they look pretty near normal. :-) That puts my knuckles about 28" off the floor, regardless of what my wife says. With my anvil at that height, I developed tennis elbow after a couple days' work doing a lot of planishing. After the therapy and in light of what the therapist taught me, my anvil face is now about 32" above the floor. I can work all day, every day at that anvil without pain or damage.

Keep a couple of things in mind when deciding where to locate your anvil. If you're going to be mostly working on finicky little stuff where you have to peer at it to see what you're doing, get it up close where you can see - you're not going to be using full over-the-head blows on that stuff anyway. If you're going to be using chasing tools a lot, or other top tools, you'll be making contact several inches above the anvil face and might want the anvil a bit lower. If you're going to be doing both picky little stuff right under your nose and also hitting top swages with a 3# hammer, you might want to seriously consider having more than just one anvil. I have four anvils, all at differing heights to accomodate different functions.

The objective is to have your joints in the proper position at the point of impact.

If you're going to be forging a lot of 3" bar stock, forget changing the anvil height and get a power hammer. You'll be glad you did!

Rich