Factor fixed costs into profit margin calculation

[JMR]

Need a small bit of help with what is probably a very simple question!

I purchase products from a manufacturer and sell to the public and also to trade via my website.

It's simple enough to work out the total cost of each product (actual cost, shipping, PayPal transaction fees, packaging etc)
I can then use the sale price of the product to figure out my profit margin on each product.
What I can't figure out is how to factor in the 2 fixed costs I have, i.e. not directly related to a product sale, which are advertising and storage costs.

I know what these costs are but how do I allow for them in the profit margin calculation?

All help appreciated

 

[WizardDr]

This is a fairly simple outline:

Suppose your typical product (or bundle) has VARIABLE costs of €150

And you Sell for €200

Then you get a 'contribution' of (200-150) = €50 per bundle to Fixed Costs and Profit.

Fixed Costs (say) €5,000.

Desired Profit Nil (to see break even first)

€5,000 divided by €50 = 100 bundles you must sell to break -even

Profit (required say) €10,000.

Required Contribution (5,00+10,000) = €15,000 divided by €50 = 300 bundles.

Suppose you know you will ONLY sell 200. And you want the €15,000 'contribution'

Then €15,000 divided by 200 = €75 contribution per bundle.

Sale price (variable per unit plus contribution per unit) 150+75 =€ 225

(This is a really short summary - key is some costs vary with sales - others don't)