Set up a calculated date field based on other fields

HubSpot Ideas
1

My objective is simple (I dit it multiple times in Salesforce):

- Having sales rep set up a “Contract Start Date” manually in a date field

- Having the same sales set up a “Contract Length” manually in a picklist field (1 / 2 or 3 years)

- Having another field which calculates automatically the “Contract End Date” in another field by adding (365 days x number of years of the contract) to the “Contract Start Date”

Apparently, this very basic computation seems impossible to do in Hubspot with Workflows (cannot use relative date in the calculating field), and I do not want to add a “Waiting Step” of 365 days in the workflow.
How can I proceed?

3

This is still an open gap, HubSpot workflows only do relative-to-now date math, not field-plus-field. Until it ships, the workaround I use: calculate the end date externally (contract start plus 1/2/3 years, accounting for leap years) with a free date calculator like date and units, then set that value into the deal/contact via a simple workflow action or during import. Not native, but it avoids the 365-day waiting-step hack.