Margin from shelf price will be calculated using the formula:
(Shelf price without VAT - Cost) * 100 / Shelf price without VAT
For example:

($96 - $50) * 100 / $96 = 48% margin

Margin from shelf price will be calculated using the formula:
The calculation is: (Rec price without VAT - cost)*100 / Rec price without VAT
For example:

($76 - $50) * 100 / $76 = 34% margin

The margin is shown on the product's page. The shelf price margin shows near the shelf price in the system, and the recommendation margin will show in the Margin value, and near it, the difference from the current margin. 

For example, the following product page:

The shelf price margin is 16.59 
The recommendation margin is 18.34, and the difference between them is 1.75%

To read how to set up limits check our Rounding & Limits guide here
You can also set up a margin or limit per rule inside the strategy, to read more about this feature, please check our guide here 

If you have questions about the margin calculation you can ask our dedicated support team, or check out our guide Margin is incorrect/equal or below zero.