storage costs that vary in weight each month

I'm trying to automate storage fees. We need to charge for materials that sit on our floor. In most cases there is a monthly print run that would remove a portion of the inventory. I thought it would be great if I could have excel do the lifting for me. Here is an example of what I'm looking at.

Variable data;
Time frame in number of months - 11 (first month is free)
Total weight - 12,000 lbs
Weight per skid - 1,000 lbs
Cost per skid - $8

I divide the total weight by 12, then multiple by 11 (months) then divide by the skid weight and round up. I then take this number (in this case 11) and multiply by $8 = $88 for the first month. I repeat this process for the remaining 10 months and come up with $1056.

Is there a simple way to do this? Thanks in advance for you help!

Chris

Thanks RatCat for the lighting fast response! My apologies for doing a poor job of explaining it but the amount of weight / skids would be reduced each month. For an easy example if I were to use $10 per skid, 12,000 lbs total lbs of product and 1000 lbs per skid. So after the first month goes by at no charge I'm left with 11m lbs, 10m lbs the 2nd month, 9m lbs the third month - etc. So after 11 months of chargeable storage I would get $660 bucks. I think your formula (one free month) is coming up with $1320. I will look into it tomorrow - a little to tired to think properly at the moment. Thanks again for your help - I'm much closer to a solution.

Thanks again Ratcat! That works like a charm.