Frequently Asked Questions
Quick answers to the questions people ask most about Date Math. Can’t find yours? Get in touch.
- Is Date Math free to use?
- Yes. Every calculator on Date Math is completely free, with no account, no sign-up, and no paywall. The site is supported by unobtrusive advertising.
- Do I need to create an account?
- No. There's nothing to sign up for and nothing to log in to. Open the site and start calculating immediately.
- Is my data private? Where do the calculations happen?
- Your calculations run entirely in your browser, on your own device. The dates and numbers you enter are never sent to or stored on a server. The only data collected is standard, anonymous usage analytics, as described in the Privacy Policy.
- What is the difference between calendar days and business days?
- Calendar days count every day, including weekends and holidays. Business days (or working days) count only Monday through Friday and, when you choose to exclude them, skip public holidays as well. That's why '10 business days' usually spans two full calendar weeks.
- Which countries' holidays are supported?
- Date Math can exclude public holidays for the United States, the United Kingdom, Canada, and Australia. Turn on 'Business days only,' then enable 'Exclude holidays' and choose your region. If you'd like another region added, get in touch through the contact page.
- How are holidays calculated?
- The tool computes commonly observed public holidays for each supported region, including fixed-date holidays like New Year's Day, floating holidays like the U.S. Thanksgiving, and Easter-based holidays like Good Friday. Holiday observance can vary by region and year, so for legally significant deadlines you should always confirm against an official source.
- Why does 'one month after January 31' not land on a 31st?
- Because not every month has 31 days. When the matching day number doesn't exist in the target month, the date rolls into the following month. If you actually want the last day of a month, use the Next / End Of tool, which finds period boundaries exactly.
- How do I subtract time instead of adding it?
- In the Add / Subtract tool, enter a negative amount — for example, -7 days means seven days earlier. In the From Now tool, choose the 'Ago' direction to count backward from today.
- Does counting the days between two dates include both the start and end date?
- Date Math reports the difference between the two dates (the gap). If you need to count both endpoints — for example, a multi-day event that runs 'from the 1st through the 8th' — add one to the result.
- Can I share or bookmark a calculation?
- Yes. Your inputs are stored in the page's web address, so you can bookmark a result or paste the link to someone else and they'll see exactly the same calculation.
- Does Date Math work on mobile and in dark mode?
- Yes. The site is fully responsive and works on phones, tablets, and desktops. You can switch between light and dark mode using the toggle in the top-right corner.
Want to understand the details behind these answers? Browse the guides for in-depth explanations of business days, days-between calculations, and more.