Free · offline · no sign-up
Date calculator
Pick two dates and get the exact number of days, weeks and months between them, or start from one date and jump forward or back by a number of days. It runs entirely in your browser, so it keeps working with the Wi-Fi off.
Opens a fresh page with just this tool on it. Everything else is one click away.
How to use it
- 1 Choose a start date and an end date to see the span between them.
- 2 Switch to add or subtract mode to move a number of days, weeks or months from a single date.
- 3 Read the result in days, weeks and months at once, with no conversion needed.
- 4 Change the output format from the block's options menu, from 2026-03-14 to March 14, 2026 and more.
- 5 Keep it on your canvas next to the note or task the date belongs to.
Frequently asked questions
How do I calculate the number of days between two dates?
Enter the earlier date as the start and the later date as the end. The calculator returns the total number of days between them, along with the equivalent in weeks and months.
Does the calculation include the end date?
The default result is the difference between the two dates, which excludes the end date. Counting both the first and last day means adding one to the result.
Does it handle leap years?
Yes. The calculation uses real calendar dates, so leap years and differing month lengths are handled automatically.
Can I use it without a mouse?
Yes. Type + or - to switch between add and subtract, D, W or M for the unit, and Enter to calculate. In the date picker, arrow keys move a day or a week at a time, crossing into the next month on their own, and Enter selects the highlighted date.
Is it free, and do I need an account?
It is free and needs no account. KontrolRoom runs locally in your browser and your data never leaves your machine.
It is not just this one tool
The date calculator is one block inside KontrolRoom, a modular workspace with notes, a calculating workbook, task boards and 20+ other utilities you can arrange on a single canvas. It all runs locally in your browser, works offline and costs nothing.
Explore the full workspace