If you are using the "compare at" price field, how do you show the percentage discount your regular price is? This took me a little time to figure out, so to save you the trouble here is the liquid code I used:

{{ product.compare_at_price_max | minus:product.price | times:100 | divided_by:product.compare_at_price_max }}%

If you capture this as a variable "discount":

{% capture discount %}
{{ product.compare_at_price_max | minus:product.price | times:100 | divided_by:product.compare_at_price_max }}%
{% endcapture %}

You can now say "Save up to {{ discount }}".

Alternatively, you if you use the minimum variant price (product.compare_at_price_min) you can say "Save at least {{ discount }}".

To see the decimal points of the percentage, use "times:100.0" instead.

You can see an example on the datelite store.