ToolbitDate Difference and Duration Calculator
Work out how many days are left on a certificate, what date a 90-day retention window ends on, or how far apart two log entries are.
What the Date Calculator does
- Difference between two dates in days, weeks, months, and years.
- Add or subtract any duration from a starting date.
- Business-day counting that skips weekends.
- Handles leap years and month-end rollovers correctly.
How to use it
- Pick your start date.
- Enter a second date, or a duration to add or subtract.
- Read the result in the units you need.
Why it runs locally
Toolbit has no backend. The Date Calculator is implemented with standard browser APIs, so your input is processed in the tab and never uploaded, logged, or retained. That is what makes it safe to paste real data into — and it is also why the tool keeps working with the network disconnected, once you have installed Toolbit as an app.
Frequently asked questions
- Can it count business days only?
- Yes. Weekend-excluding mode gives the working-day count between two dates.
- How are month boundaries handled?
- Adding a month to 31 January lands on the last day of February rather than overflowing into March.
- Does it work offline?
- Yes. Toolbit installs as a PWA and ships as a desktop app for macOS, Windows, and Linux, so the whole toolbox keeps working on a plane, behind a corporate firewall, or on an air-gapped machine.