Can't help you. There is no typical way of pricing this kind of install. It really is whatever happens to be the general practice in your area.

Your contractors have two different ways of coming to almost the exact same price. There is no way you are going to save any money here. Pick the best contractor and be done with it.

I did run into this question from consumers over the years. We used to install tons of sheet vinyl, linoleum and vinyl tile. We priced it product plus labor per square foot, whether or not all of the product wound up on the floor. You would think that to be a little unfair, but it is not. The simple fact that we had to handle the piece of goods, didn't mean we had to discount in any way the material that we touched, but did not glue down.

Thanks Glennsfc. I don't think the pricing is unfair but it is a trade I have little expereince with and want to be an educated consumer. Both contractors come recommended. I can understand the pricing as it applies to vinyl sheet since it comes in set widths. You buy a piece big enough to cover and trim out what is not needed, but you still have to buy a big enough piece. here the contractor says buy 75 more sf ft for waste than the first contractor's waste allowance and I'll charge you to install it at $2.75/ft and you can return (maybe, I did not check with supplier) unopened boxes but I'll still charge you to install all the boxes. Any sense of why one contractor says 10% waste needed and the other 20%. Both are familiar with the product and say it is one of the better ones quality wise.

Are you thinking that you can go back to Contractor B and say "I only want to buy 600 sf, will your install price go down?" I doubt it, but you could ask.

You need to compare total costs between the 2. If your material cost is $5/sf, then:

Contractor A:
materials: 600 sf @ $5/sf = 3000
labor: 935
total = 3935

Contractor B:
materials: 675 sf @ $5/sf = 3375
labor: 928
total = 4303

So using Contractor A will save you $368, but you will have more potentially left over at the end. BTW, keeping extra for future repairs is a good idea.

My experience with installing hardwood is that wastage is pretty small, since you can use the off cut from the end board as the starter on the next row. Or else you can find a board that only needs a couple inches cut off to finish up a row. 10% was more than enough on our floors. Contractor B, who says buy 20% either isn't a very good installer or doesn't trust the wood you're buying.