How to Aggregate Google Calendar Events and Total Time by Month

Google Calendar events grouped to calculate monthly time totals

To aggregate Google Calendar events, choose a fixed date range, calculate each event’s duration, group matching events by keyword or category, and add the durations. Use the same event names and date boundaries each month so the totals remain comparable.

This guide focuses on calculation: how to total calendar time by month, project, client, or activity. For the broader choice between Time Insights, exports, and analysis tools, start with Google Calendar Analytics: How to Analyze Calendar Data and Time.

The Google Calendar event-duration formula

For each event:

Event duration = end time − start time

Then add the durations of all events that match the same category or keyword:

Category total = duration of event 1 + event 2 + event 3 …

Example:

Event	Start	End	Duration
Work \| Client A meeting	09:00	10:00	1 hour
Work \| Client A design	10:30	12:00	1.5 hours
Work \| Client A review	15:00	15:30	0.5 hour
Client A total	—	—	3 hours

Use duration rather than event count. Three 30-minute meetings and three two-hour meetings have the same event count but very different effects on the day.

Prepare event names for accurate totals

Grouping works when related events share a stable word. Use a pattern such as Category | Detail:

Work | Client A meeting
Work | Client A design
Study | Spanish
Health | Running

Decide whether the total should be based on a broad category such as Work or a narrow keyword such as Client A. Avoid accidental variants—“Client A,” “Client-A,” and “A project”—if they should belong to one group.

Choose a complete date range

Use fixed boundaries before calculating:

Weekly total: the same seven weekdays each time
Monthly total: the first through the last day of the month
Project total: the agreed project start and end dates

Do not compare a partial current month with a complete previous month unless the comparison is explicitly month-to-date.

Method 1: Find and total events manually

Google Calendar search can filter events by keyword and date range. Search for the shared term, open each relevant event, calculate its duration, and add the results in a note or spreadsheet.

Open Google Calendar on a computer
Select Search and enter the category, client, or project keyword
Use advanced search to set the date range
Record each matching event’s start and end time
Calculate and add the durations

Google notes that Calendar search results are limited, so this method is best for a small number of events. See Google’s official search instructions.

Method 2: Export events and calculate in a spreadsheet

Google Calendar can export calendar data as iCalendar files from a computer. Google’s documentation says the exported data can include event start and end times, recurrence information, invitees, titles, descriptions, and locations when available.

Export the required calendar from Google Calendar settings
Convert or import the event data into a tabular format
Create a duration column using end time minus start time
Create a category column from the event title or calendar name
Sum duration by category, keyword, project, or month

Follow Google’s calendar export guide. Work or school administrators may restrict exports, and exporting is only available on a computer.

Useful spreadsheet columns

Column	Purpose
Date	Groups events by day, week, or month
Event title	Provides the source keyword or project name
Start time	Beginning of the event
End time	End of the event
Duration	End time minus start time
Category	Normalized group such as Meeting, Study, or Client A

Method 3: Repeat the calculation with Kotomil

Kotomil connects to Google Calendar and aggregates events for a selected date range. Use event-title keywords to review total time, ratios, and changes without exporting the calendar for every report.

Select a complete week or month
Review the total event time
Filter or group events using a consistent keyword
Compare the same keyword with the previous period
Record the largest change and the action it suggests

Start with one calculation, such as Meeting hours or Client A hours. Adding many categories before the event names are consistent makes the result harder to trust.

Calculate monthly Google Calendar totals

Use the first through the last day of the month and calculate these values in order:

Total calendar time: duration of all relevant events
Category total: duration of events containing a shared category
Time share: category total ÷ total calendar time × 100
Month-over-month change: current total − previous total

For example, if meetings total 24 hours out of 80 recorded work hours, the meeting share is 30%. If the previous month contained 18 meeting hours, meeting time increased by six hours.

Avoid common aggregation errors

Overlapping events: decide whether simultaneous events should count once or separately
All-day events: exclude reminders and labels that do not represent actual duration
Planned versus actual time: update events or keep the two values separate
Inconsistent names: normalize synonyms before grouping
Incomplete periods: compare equivalent date ranges

Document the rule you choose and reuse it. Consistency makes a recurring total more useful than a theoretically perfect calculation that changes every month.

What to do after calculating the totals

A total becomes useful when it leads to a question: Why did meeting hours rise? Which client consumed more time than estimated? Did study time disappear on weekdays?

To interpret those results and compare analysis methods, return to the central Google Calendar analytics guide. For a recurring reflection process, see How to Do a Monthly Review with Google Calendar.

Summary: calculate duration, group, and compare

To aggregate Google Calendar events, calculate each event’s duration, group events with a consistent keyword, and add the durations over a fixed period. Use manual search for a small dataset, an export and spreadsheet for custom one-off work, or Kotomil for a repeatable monthly calculation.