Does a 60 hour project take you 60 hrs… Or 20… Or 120

I have a software integration being built for me, I tried to do it but don't have the skills. The (much better) dev I hired says it's a 60 hour project… But won't be able to deliver until March. Just curious in general for those freelance devs or if you give a time estimate at work – how close are your estimates in general?