How to add different sizes to one product?

Say for example I am selling perfume. I have perfumes with different size such as 15ml, 30ml, 40ml etc and they have different prices.

I want to list one perfume and have the option where customer can select the size she wants and at the same time the price must change and reflect the cost for the size of the perfume selected.

Remember different brand of perfume would have different prices too, so must reflect correctly.

What is the best can I so this? thanks for your help.

Just. Use options and option

Modifiers for pricing.

Please explain. Are you referring to global option and its variant? Or product features?

go into you product, the click the options tab.

In here you will Add an option call it size or whatever and choose select box, then save, go into variants tab in the said oprion and add your avariants, 10ml +0 15ml +50% etc

thne when on the storefront the customer can add these and see the price change when selected

OR ! read this