Reading through the replies, the generic answer tends to be 'overestimate' or 'multiply the time you think by x', and honestly, those aren't bad answers. Getti

Reading through the replies, the generic answer tends to be 'overestimate' or 'multiply the time you think by x', and honestly, those aren't bad answers. Getting a feel for estimation is the hardest part of consulting, and it gets worse, as every customer is different. I've had customers who came in WAY under deadline (which is a problem, because it means I have empty calendar days and am not getting paid), and I've had customers in came in WAY over deadline (which is a problem, because it means I'm pushing back other obligations or start dates.) I tend to average somewhere around 'on time', but there's no magic bullet for it, and even if there was, the customer would likely either eat/break/object to your use of a magic bullet, or expect receive ownership of said bullet at the project's completion. In the mechanical industry, this is mitigated by extensive knowledge of how long things take, and on averaging. If I call the local Jeep dealership, and ask how much it will cost to replace my transmission, they have a database they look in, which is effectively an average of how long transmission replacements have taken over the history of however long they've been replacing transmissions. They know the material cost, and they have a good average on the labor time (and of course they know the labor rate). They have experience in estimating that sort of work -- without it, their system would be largely useless. Aside from that, until you get that experience, the best advice is the oft-submitted (multiply by 'x'), and make x as generous as you think you can get away with until you get some more estimating experience under your belt.