Add or Subtract Days From a Date

What is add or subtract days from a date?

This tool moves a date forward or back by a set amount of time. It answers questions such as what date is 90 days from today, when does a 30 day trial end, or what was the date 6 months ago.

Typical uses are invoice due dates, return windows, medication schedules, project milestones and legal notice periods.

How to use the add or subtract days from a date

1. Pick the start date, usually today.
2. Choose add or subtract, enter a number and select the unit.
3. Press Calculate to see the final date, its weekday and the ISO format.

How the add or subtract days from a date works

Days and weeks are added as exact day counts. Months and years move the calendar month or year. If the day does not exist in the new month, such as 31 April, the date rolls into the next month, which is how most software behaves.

Worked example

Common uses of the add or subtract days from a date

• Finding the due date of an invoice with net 30 or net 60 terms.
• Working out the end of a free trial or return window.
• Planning medicine courses, project phases or training schedules.
• Calculating a pregnancy milestone or a school term end.
• Going back in time to find the date 90 days ago.

Tips and common mistakes

For payment terms such as net 30, use days. For subscriptions that renew monthly, use months.

Check the weekday in the result. If it lands on a weekend or holiday you may need to move it.

Background: what to know before you rely on it

Adding time to a date is easy for days and weeks but harder for months and years. Most software handles month ends by rolling forward, so 31 January plus one month becomes early March, not an invalid 31 February. Financial systems may instead use the last day of the month. If your contract has a rule for this, follow the contract. For legal deadlines, also check whether weekends and holidays move the final day to the next working day. This tool gives the plain calendar result and the weekday, so you can see at once when a date lands on a weekend.

Private, free and fast

This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all date and time tools, or browse the full list of tools.

Related tools

Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. For legal deadlines, confirm how your contract or court counts days.