Date calculators · Workdays & planning
Appointment Capacity Calculator
Fit appointments into opening hours around breaks and blocked time. Include before and after buffers and see exact slots plus unusable fragments.
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Select your counting rules and calculate.
Calculation details
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How to use this calculator
Enter an appointment date, duration and buffers. Add opening periods and unavailable periods. Calculate to see the appointment times and the full protected block for each slot.
Overlapping openings merge, and overlapping blackouts count once. A complete appointment with both buffers must fit in a remaining opening. Slots cannot bridge lunch, a blackout or the closing boundary. Times are same-day wall-clock times.
A worked example
A 09:00–12:00 opening with 30-minute appointments and ten-minute after buffers fits four protected slots and leaves 20 minutes unused. A blackout can reduce capacity further by splitting the available time.
Are buffer rules the same on every booking platform?
No. This tool requires buffers inside the opening period. Some providers allow buffers outside availability; use the entered rules as a planning model rather than a reproduction of provider behavior.
Further reading: Source workflow and conventions. Your entered rules determine this result.
Which calendar and years are supported?
Use Gregorian dates from 1900 through 2100, with results inside that range. Most daily plans are limited to 366 dates; academic terms and sprint plans allow up to 731. Forms limit the number of entries to keep calculations responsive. Holidays and policy rules come from your inputs. Date-only plans ignore DST; tools with time-zone inputs use the browser's time-zone data and explicitly resolve repeated times. Calendar exports preserve date-only markers or exact timed events as appropriate. Calculations run only when requested, without background polling.
What happens to my dates?
Calculations run on your device. Saving a calculation is optional and keeps it in this browser. A setup link contains the dates and settings you entered; anyone with the link can read them. Use one tab per saved calculator. Clear saved data from Privacy & settings.