PPC - Something to consider when evaluating and optimising a campaign

I built a simple table where you can easily see the relationship between CPC (cost per click), CPA (cost per acquisition) and CR (conversion rate) when evaluating and optimising a PPC campaign.
 The table below answers for example to the following questions: 

1. Given a cpc and a max CPA, what's the minimum CR we need to have a successful campaign? This means:If you pay an average cost per click of £1 and you don't want to spend more than £10 per conversion --> check the table --> your campaign and landing page should guarantee at least 10% conversion rate (= every 10 clicks, 1 conversion.
2. The conversion rate of my campaign is XX but I am spending to much per conversion. How much should I low the cpc in order to match my target CPA?This means: If your current CR is 10% and you want to spend 5£ (instead of £10) for your conversions --> check the table --> your cpc from 1 should go down to £0.50 I hope this helps.

Feel free to contact me if you want the xls file or if you simply need help reading the table.