About Date Math

Why this exists

I’m an independent software developer, and I built Date Math to scratch my own itch. I kept running into the same small problems: “What date is 45 business days from now?” “How many days until the project deadline?” “If I start a 90-day trial today, when does it end?”

Every time, I’d open a search engine, land on a page buried under pop-ups and newsletter prompts, count on my fingers, or wrestle with a spreadsheet formula. None of it was fast, and none of it respected my time. So I made the tool I wished already existed: one clean page that answers the question the moment you type it.

What Date Math does

Date Math is a free online date calculator with four focused tools, each built around a real question people ask:

• Add / Subtract — take any date and move it forward or backward by a number of days, weeks, or months. Try it.
• From Now — find the date a set amount of time from today, or that many units ago. Try it.
• Between Dates — count the days, weeks, or business days between two dates, and copy the answer as a ready-made sentence. Try it.
• Next / End Of — jump to the next Monday, the next business day, or the end of the current month, quarter, or year. Try it.

Three of the tools can switch into business-day mode, which skips weekends, and can also exclude public holidays for the United States, the United Kingdom, Canada, and Australia. If you want the details, the guides walk through how each calculation works.

The principles behind it

These never change, even as features get added:

• It’s free. No paywall, no “pro” tier hiding the useful parts.
• No accounts. There’s nothing to sign up for and nothing to log in to.
• Your dates stay yours. Every calculation happens locally in your browser. The dates you enter are never sent to a server. See the Privacy Policy for specifics.
• Shareable by design. Your inputs live in the page’s web address, so you can bookmark a calculation or paste the link to a colleague and they’ll see exactly what you saw.

How it’s built

Date Math is a static, modern web app — no tracking pixels following you around, no heavy frameworks slowing the page down. It works on your phone, tablet, and desktop, in light mode or dark mode, and the math is instant because it runs on your device rather than a remote server.

Get in touch

This is an actively maintained, one-person project, and feedback genuinely shapes what gets built next. If you’ve found a bug, want a new holiday region, or just have an idea, I’d love to hear it — head to the contact page. If you’re curious about common questions first, the FAQ covers a lot of ground.