Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Total days
0
Business days
0
Weeks
0.00
Weekend days
0
Approximate months
0.00
Approximate years
0.000
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter start date.
- 2Enter end date.
- 3Read your total days on the right — it updates as you type.
- 4Hit Share to keep the scenario or send it to someone.
About this calculator
Calendar math is deceptively easy to get wrong because of leap years and month lengths. This counts the exact elapsed days and breaks out business days separately.
Worked example
Using the values the calculator loads with:
Inputs
- Start date: 2026-08-15
- End date: 2026-08-15
Results
- Total days: 0
- Business days: 0
- Weeks: 0
- Weekend days: 0
- Approximate months: 0
- Approximate years: 0
What each field means
Inputs
- Start date
- The reference date for this calculation. Defaults to today unless you change it.
- End date
- The reference date for this calculation. Defaults to today unless you change it.
Results
- Total days
- Returned as a whole number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Business days
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Weeks
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Weekend days
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Approximate months
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Approximate years
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the days between dates calculator work?
Calendar math is deceptively easy to get wrong because of leap years and month lengths. This counts the exact elapsed days and breaks out business days separately. The underlying maths is: Days = (End − Start) ÷ 86,400,000 milliseconds.
What do I need to enter?
2 values: start date, and end date. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the total days result mean?
It is returned as a whole number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Estimates assume standard, average conditions — local rules, pricing, and materials vary.
Who is this tool for?
It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Days Between Dates Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/days-between-dates
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/days-between-dates" target="_blank" rel="noopener">Days Between Dates Calculator — RevenueLab</a> (2026).</p>
Source: [Days Between Dates Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/days-between-dates) (2026).