Question 1

How do negative values work?

Accepted Answer

They subtract along the chosen unit. Useful for back-planning: if the filing must arrive by the 30th, subtract the required lead time from that date to see the latest day you can start gathering signatures.

Question 2

Why did adding one month not equal adding 30 days?

Accepted Answer

Months have different lengths. Month-based addition tries to preserve the day-of-month when possible; day-based addition marches in 24-hour steps. Contracts may specify which interpretation governs.

Question 3

Which preset pages overlap with this tool?

Accepted Answer

Shortcuts like 30 days from today fix today as the anchor. Use this calculator when the anchor is any other date or when you need weeks, months, or years instead of only days.