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Creating a fictious period of time without overlapping periods of time

Copper Contributor



For a large project I am experiencing some trouble in managing to create a fictious period of time based on several rows of dates. I manage to create the period manually or when the period of time does not overlap. However, In my results there are large periods of time that do overlap. For example:

These periods are easy to calculate:

1: 1-1-2023 - 31-3-2023
2: 1-6-2023 - 30-7-2023
3: 1-12-2023 - 31-12-2023

The fictious period should count up to 6 months -> 1-1-2023 - 30-06-2023.


In the next example there will be some overlap:

1: 1-1-2023 - 31-3-2023

2: 1-3-2023 - 30-6-2023

3: 1-12-2023 - 31-12-2023


The fictious period should count up to 7 months -> 1-1-2023 - 31-07-2023. But if I use a formula to calculate the first example, it will count the period between 1-3-2023 - 31-3-2023 twice. Resulting in a fictious period of 8 months instead of 7.


So I am looking for a formula that could give a fictious period based on the given periods, or the amount of days without any overlapping dates. I can not find an easy to implement formula for my problem, I hope that anyone has some tips/tricks to help me. If it would take multiple steps/formulas it would also be no problem.


Many thanks in advance.

3 Replies


This is an example of the format in Excel, I can not upload a test file unfortunately.


A somewhat unusual approach on my part. First put all the days in a list and then delete the duplicates or multiples and then count them.





I hope the next formula helps you. you have to analize the overlaping dates and substract from the result