[REACT] Critical Path Explanation

[gopisetty hema]

Hi Team,

My subscription has ended, so I’m currently using a different login to continue this discussion. We will be renewing the forum subscription soon. In the meantime, I’ll continue the conversation here.

As mentioned in my earlier post, I was having difficulty identifying the correct EF and LF values. Now I am clear about the Early Finish (EF) value, which corresponds to the task’s planned finish date. However, I am still facing some confusion regarding the Late Finish (LF) value used in the slack calculation.

According to the documentation, the calculation should be:

LF: 15-Mar-2026 13:28:18 (Project finish date)
EF: 04-Jan-2026 23:27:49 (Planned finish)

Slack = LF − EF ≈ 69 days.

However, when I log the slack values in the system, it is showing 18.6 days, and you also mentioned 18.6 days earlier.

Could you please clarify which task date is being considered for calculating this 18.6-day slack value?

Attached respective forum link and screenshot for reference.
viewtopic.php?t=34844&start=10

Thanks,
Hema Gopisetty

[gopisetty hema]

Hi Team,

This is a gentle reminder regarding the explanation requested for the Critical Path.

Since this is required to proceed further, could you please prioritize this request and provide the explanation at the earliest?

Thanks,
Hema

[Arc]

Hello,

According to the documentation, the calculation should be:

LF: 15-Mar-2026 13:28:18 (Project finish date)
EF: 04-Jan-2026 23:27:49 (Planned finish)

LF and EF of which task?

If WKP-509-R20 then why do you think its latest end date is the project end date? Is it one of the last tasks of the project?

Best regards,
Arcady

[gopisetty hema]

Hello Arcady,

To understand the float calculation properly, could you please tell me exactly what EF (Early Finish) and LF (Late Finish) Bryntum is using for the task WKP‑509‑R20?
I see that Bryntum shows a slack value of 18.6 in console, but I need to understand:

What EF date Bryntum is taking for WKP‑509‑R20
What LF date Bryntum is using for WKP‑509‑R20
And therefore, how (LF – EF) = 18.6 is being derived

Once I understand the EF and LF used for this specific task(WKP‑509‑R20), I can apply the same logic to calculate slack for the rest of the tasks.
Thank you,
Hema

[Arc]

Hello,

To understand the float calculation properly, could you please tell me exactly what EF (Early Finish) and LF (Late Finish) Bryntum is using for the task WKP‑509‑R20?
I see that Bryntum shows a slack value of 18.6 in console, but I need to understand:

What EF date Bryntum is taking for WKP‑509‑R20
What LF date Bryntum is using for WKP‑509‑R20
And therefore, how (LF – EF) = 18.6 is being derived

EF is Thu Jan 01 2026 20:28:12
LF is Fri Jan 23 2026 16:00:00
If you calculate working time between the dates you get the value.

And, as I mentioned earlier here, you can read those values yourself:

You can check a task values by reading its fields
Early Finish is Gantt.model.TaskModel#field-earlyEndDate
Late Finish is Gantt.model.TaskModel#field-lateEndDate

Best regards,
Arcady

[gopisetty hema]

Hi Team,

I am trying to understand EF and LF calculation in Bryntum for the below task:

Task: WKP-509-R20
Fri, Sat ,Sun --> Holidays
Start: 12-Nov-2025 14:04:48
End: 04-Jan-2026 23:27:49
Working calendar: 9:00 AM – 6:00 PM

EF Calculation (forward pass):
Working duration = 27.564 working days
EF = Start + Duration
= 12-Nov-2025 14:04:48 + 27.564 working days
= 01-Jan-2026 20:28:12

LF (as per Bryntum):
LF = 23-Jan-2026 16:00:00

There are no active successors or constraints on this task.
As per documentation, if a task has no successors, LF should default to the project end date (in this case, 15-Mar-2026).

However, Bryntum is calculating LF as 23-Jan-2026 instead.

Could you please clarify:

1. How it is considering LF to 23-Jan-2026?

Thanks
Hema Gopisetty

[Arc]

Hello,

Start: 12-Nov-2025 14:04:48
End: 04-Jan-2026 23:27:49
Working calendar: 9:00 AM – 6:00 PM

Test case you provided to us has different values but anyway.. the task is summary. Such tasks early start and end are min(children early start) and max(children early end) respectively. The approach is used for both early and late dates.

Best regards,
Arcady

[gopisetty hema]

Hi Arcady,

Thanks for your clarification that a summary task calculates its early start and end as the minimum of children early start and maximum of children early end, and that the same approach is used for both early and late dates.

Continuing on this, I tried to analyze the child tasks under WKP-509-R20 (36 child-tasks in total).

For a sample child task 71820:

• Start Date = 09-12-2025 13:02:45
• End Date = 09-12-2025 14:02:45
• EF = ES + Duration = 09-12-2025 14:02:45

However, I am still unclear about how LF (Late Finish) is being calculated for the child tasks.

As per the documentation, if a task has no active successors, LF should be derived from the project end date. Since this task seems to fall under that condition, I expected LF to be either:

• Project end date (15-March), or
• At least the parent task end date (WKP-509-R20 – 04-01-2026 23:27:49)

But the LF values in the dataset are not matching this expectation.

I have attached the children’s LF/EF file along with the complete data for reference. Could you please clarify how LF is being derived in this case?

Thanks & Regards,
Hema

[gopisetty hema]

Hi Team,

This is a gentle reminder regarding the explanation requested for the Critical Path.

Since this is required to proceed further, could you please prioritize this request and provide the explanation at the earliest?

Thanks,
Hema

[gopisetty hema]

Hi Team,

We are currently blocked on progressing further without this information. It would be helpful if you could prioritize this request and share the details at the earliest.

Thanks,
Hema