Add / Subtract Days
Date math.
▶ Open Add / Subtract DaysAdd / Subtract Days is a free online time & date tool that helps you date math. Everything happens right in your browser, so it's fast, completely private, and free — no account, no installs, and no watermarks.
What is Add / Subtract Days?
Add / Subtract Days is built for anyone who needs to date math without downloading software or signing up. Deadlines, ages, time zones and timers come up in work and life all the time. Add / Subtract Days solves that in one click, right in your browser — and because the work happens on your own device, it's both instant and private.
How to use Add / Subtract Days
- Click “Open Add / Subtract Days” to launch the tool.
- Enter your numbers in the fields.
- Read the result — it updates as you type.
- Tweak the values to compare different scenarios.
Common uses
- Count down to an event, launch or holiday.
- Work out the exact days between two dates.
- Convert a meeting time across time zones.
- Time a task or focus session.
Why use Somar's All Free Tools?
- Free forever — every feature, no hidden paywall or watermark.
- Private by design — processing happens on your device, not our servers.
- Instant — no queues, no waiting, no upload time.
- Works everywhere — desktop, tablet and mobile, nothing to install.
- No signup — just open it and go.
Frequently asked questions
Is Add / Subtract Days free to use?
Add / Subtract Days is completely free. There are no limits, no watermarks on your results, and no sign-up required.
Is my data private and safe?
Yes. Everything runs locally in your browser, so the data you enter never leaves your device.
Do I need to install anything or create an account?
No. Add / Subtract Days works instantly in any modern browser on desktop, tablet or mobile — nothing to download and no account needed.
How accurate are the results?
Add / Subtract Days uses standard formulas and recalculates instantly. Results are estimates for general guidance; see our Disclaimer for health and finance tools.