Hi Philcott. I've done all the calculations but didn't save them. Got to £23 for a 6 month pullet when I factored everything in best I could as follows.
The obvious are the consumables-feed, electricity (depends on batch size as 50 chicks under a lamp costs the same as two), bedding, medication, sanitation. The less obvious are maintenance and depreciation on capital costs. The completely overlooked are the cost of keeping the breeding parents, so a hatching egg has a significant cost before you start. By maintenance I mean replacement bulbs, broken equipment so any repairs -quite small really.
Capital depreciation can be viewed thus -the equipment always has a reducing resale value up to it being worthless or worn out. This is highest in the first year. To make it simple just assume that it will last a certain number of hatches and divide the purchase cost accordingly. Bare in mind that if you only use the equipment once the real costs will be far higher. To be absolutely on the safe side cost on the basis that the equipment will be used once and then sold if you like, but you won't like the numbers. Ignore the interest on the investment, meaning you could have had the money in the Bank and had interest -that's almost nothing now. It only really comes into play if you borrow the money.
Past 8 weeks they may be off heat, depending on the time of year. Then the feed is straightforward but the capital is horrendous. Cost of a 10 bird coop and run that can be used once or twice a year and falls apart in 10 years! Could add £5 a bird. We also employed rearing units - built 4 which can be used as broody rearers, isolation coops, emergency coops and broody breaker runs when separated. Extremely useful.
So if you ignore most of the capital side as your equipment is now 'free' it is still a complicated equation! Hope this helps. I decided to forget about it. Market forces dictate the selling prices, so if everyone thinks they are making a profit but are actually making a loss I am stuck with it.