Estimating azure running costs

A friend has asked me to quote him for a simple web application with low traffic (it’s a site for customising products only accessed by customers who’ve already placed an order), I’ve come up with a simple design and know roughly what azure services I would need however I have absolutely no idea what to charge.

I’ve arrived on a number for my own time but am struggling to figure out how to quote for the running of the sites and services.

Is there an easy way to gauge costs?