Firstly I'm a complete beginner where tap and dies are concerned. I have a set, but up to now its either been done before I get the part or I got a mate to do it for me. But I can't keep asking people for help every time I need to tap something. So I'm starting to do this myself, with a bit of help from you guys.

I've bought 2 fencing panels so I can fence off part of my backyard as I don't have a garden shed but do have a lean too at the back of my Bungalow but its open to any one who walks up the garden path, hence the panels. One of these panels need to be anchored to a concrete post so I have to make a wire clamping gadget (to buy one cost £70) out of bits and pieces but this entails drilling and tapping a couple of holes to take an M5 bolt.

I found a Tap and Hole calculator at Theoretical Machinist . com (see Attachment), but it might as well be written in Klingon as I have no idea what the calculator is asking for.

All I really wanted to know is how big a hole do I have to drill to tap for an M5 bolt.