Definitely overestimate and quote for worst case scenarios. This type of work isn't fun when you know you're going to get stuck doing a lot of extra work for th

Definitely overestimate and quote for worst case scenarios. This type of work isn't fun when you know you're going to get stuck doing a lot of extra work for the minimum amount of compensation. And like michaelhart said, sending an invoice for less than what you quoted will no doubt make the client happy. I quote a range for friends because I want to charge them as little as possible while getting -something- for providing that value.