Create custom field in multiple modules

Create custom field in multiple modules

I am trying to create some custom fields that will be in both leads and contacts module without having to create them separately and then mapping them. How is that performed? it is too time-consuming to create 20+ fields and then do the same thing in a different module when they carry the same info.
The idea is that when we get a lead from web site, there are items that we capture and once that lead is a client and moved to Contacts, that info should come over. So trying to find an easy way to create custom fields in both Leads and Contacts.
Thank you.