Do you run out of building supplies mid-project? If so, the odds are pretty good that you're not really a good estimator. If you'd like your building jobs to be a success you must find a way to accurately estimate that materials which are needed and the amount of time the work will require. As an example, say you have a wall you need to put a door frame in. It's hopeless to say how much by just looking at the wall the job will cost. You must thoroughly assess the wall, take measurements and check prices. Guesstimating will not only result in the loss of cash. It will make you lose out on contracts that may have been yours. It will likely be your insufficient effort and time that can lose those jobs for you. Suppose you quote and overestimate a a price that is high. You'll likely lose that job to the man who did great estimates and came up with a price that is lower. Any good competition that you have in the construction market will make correct and attentive approximations. Don't foolishly lose money through laziness. Guesstimating properties you in trouble because each job is different, and merely because a job should, in theory, be just like one that you have worked on before, it will not necessarily mean that it will be. Whilst you must not ignore your past experience totally, you do have to be careful of not completely taking into account what actually stands before you. Thus, don't let any be a guesstimate. Use mathematical techniques and scientific methods. Perhaps you need to find a mentor who has more experience than you do making estimates. Irrespective of how frustrated you may get, no guessing! In the long term, you will be laughing all of the approach to the bank. You had enough builder supplies equipment to finish the job, will have won the job, and won't be borrowing from the current job to cover a past job.