What's the preferred method of determining IBU

I've been messing with some different recipes for a Mirror Pond clone and am trying to pin point the IBU for the modified recipe. I've seen a few tables online and in some books but they don't seem to agree. Whats your method of calculating IBU based on hop schedule?

As you have observed, there are several ways of calculating IBU and they don't agree. Tinseth & Rager are the most common methods and they don't agree.

I leave Recipator set on Tinseth, because I really don't think one is any better than the other. Unless you are planning on having your ale tested by a laboratory, you won't know what you have anyway. My hopwine came out at 281.8 IBU, not likely, but fun to mention.

That'll make you pucker.

Are Tinseth equations based on hops pellets or whole hops?