Calculate Retail Price based on desired profit margin

Hi,

I have an excel sheet containing products which I sell and I am trying to work out a formula to give me a retail price (selling price) based on a desired profit margin taking into account all costs and fees. My spreadsheet is set out as follows:

Column H - Cost of goods from supplier
Column I - Cost of delivery from supplier
Column J - VAT (20% of column H an I)
Column K - Total Cost (total of H,I and J)
Column L - Postage Credit (credit received from Amazon when selling on their site)
Column M - Fees (variable fees owed to Amazon, 0.13*column L and column N)
Column N - Retail price i.e. price I will sell the item for
Column O - Profit =SUM(N4+L4)-(K4+M4)
Column P - Profit % - This is the column where I wish to enter the desired margin percentage to calculate column N

Any help would be appreciated as this has me beat!

Graham

The issue is column M, as this is a variable (13%) of the retail price so I want the margin to be whatever is in column P taking into account both the total cost and the fees in column N...

Thank you, when I do that =SUM(L4/(1-N4-Q4)) however I get a circular reference error as column N (fees) is calulated as 13% of the retail price

Thank you and apologies if I have misread but this doesn't achieve what I am looking to do which is have excel automatically calculate the sell price based on a entered gross margin but taking into account both the cost of goods and amazon fees...