# Calculate the difference between two timelines with General Caster

Hey!

I’m looking to use the integration with General Caster to perform calculations on Timeline columns.

I have two Timeline columns where I want to perform calculations: “Estimate Timeline” and “Timeline”. I have two Numbers columns where I want to write the results: “Launch Date Variation” and “Deadline Variation”.

My goal is as follows: I want to calculate the difference (in days) between the estimated Launch Day (in “Estimate Timeline”) and the actual Launch Day (in “Timeline”). I want to do the same thing for the Deadline.

I tried using this formula to calculate the difference between the two Launch Day dates:

``````DAYS(LEFT{Campaign's Est. Timeline},LEFT{Campaign's Timeline})
``````

And I used this formula for the two deadlines:

``````DAYS(RIGHT{Campaign's Est. Timeline},RIGHT{Campaign's Timeline})
``````

However, it doesn’t work; nothing appears. Does anyone know how to fix it?

Léandre

Hi @Leandre_R ,

pls try these formula given below.

Launch Date Variation:
DAYS({Campaign’s Est. Timeline}[1], {Campaign’s Timeline}[1])

DAYS({Campaign’s Est. Timeline}[2], {Campaign’s Timeline}[2])

you need to replace `[1]` and `[2]` with the appropriate index numbers based on the position of the Launch Date and Deadline in the Timeline columns.

1 Like

Hey!

Thank you so much for your help!

Unfortunately, it doesn’t work. I set my index range as [0] for the launch date (because it’s on the left in the timeline) and [1] for the deadline (because it’s on the right).

When running, Monday says “An unexpected error occurred”