Well, to CYA, it is always a good idea to use at least 2 completely separate methods to come up with your bid, and compare the results. If your methods for calculating a bid are accurate, these results should all be nearly the same. If they are not, you've got something wrong in one or more of your bids (probably in the cheaper one
).
I personally NEVER give a price to a GC (or even most other situations) right on the spot when I go size up a job. My bid method is WAY to complicated to do on the site. I tell them to expect the bid in 24-48 hours, depending on how busy I am. My simplest bids are 2-pagers, but I have presented bids with as many as 10 pages for the large complicated jobs - as I spell out every single detail of work that will be performed, I explain why "extra" steps like priming & extensive prep are really necessary (even the GC's need to see this sometimes to get them to realize they'll save money in the long run by spending a bit now & doing it right from day 1), and I even include a proposed schedule. (
A proposed schedule in a bid? Is he crazy?!?) I do this for a few reasons... It allows me to break down the job step-by-step - which DOES take some time (I type fast) but it is SO worth the time IMO because once I have a proposed schedule I now know exactly how long this job will take, and exactly what materials & consumables I will need to supply; but the MAIN reason I include the proposed schedule is because in the last 3 months (when I started including the proposed schedule) I have submitted 10 bids and won 9 jobs. It really seems to make a big difference for me.
Then, once the comprehensive & detailed bid is complete, I'll figure the job from scratch by one of the sq ft methods. I usually use "actual sq ft of coverage" instead of "heated floor sq ft" for the calculations, more accurate
Don't forget all the details that are not included in the sq ft price when doing this.
Never forget to include a precentage for your overhead (which is always extensive for licensed contractors, be sure you don't forget the little things) and a percentage to cover any unforseen expenses which may occur during the course of the job.
The real trick to bidding GCs is to bid high enough that you will do well, but not as high as your competition is asking. Sometimes this is not possible, especially when dealing with a GC that couldn't care less about quality of work from his subs, and/or being in a market with a lot of lowballer slopjockeys... I believe this is why GCs have a bit of a bad reputation in our business. I have found a rare few in the past which I can work with, and I actually work for a great one now.
Good luck on your bid.