Use the early tool
Add or subtract a precise duration and show the resulting local date and time.
What early.by is for
The name emphasizes a deadline: always state what must happen by that time.
Keep the date and time zone visible
A clock reading or duration can cross midnight. Include the calendar date, UTC offset and named time zone whenever a result will be shared.
Continue on Time.now
The permanent resource is https://time.now/time/calculator/. The full Time.now destination is available now.