Purpose and scope
What this dashboard measures
Calculate total and free float from task timing and successor constraints.
Earliest start day, Activity duration days, Latest permitted finish day, and Successor earliest start day feed the supporting figures beneath the Project Slack and Float Calculator headline; Keep Successor earliest start day in its entered unit for comparison.
Instructions
How to use this calculator
Set Earliest start day and Activity duration days from the Project Slack and Float Calculator source record, then keep Latest permitted finish day and Successor earliest start day in their recorded units.
- Set Earliest start day and Activity duration days from one Project Slack and Float Calculator reporting period.
- Set Latest permitted finish day and Successor earliest start day without changing the Successor earliest start day unit.
- Build the Project Slack and Float Calculator and compare its headline with supporting figures.
Interpretation
Interpreting the headline metric
Positive float indicates timing flexibility in the simplified network; negative float indicates a violated constraint.
Inspect Earliest start day, Activity duration days, and Latest permitted finish day beside the Project Slack and Float Calculator headline; Successor earliest start day reveals rounding across the supporting figures.
After the Project Slack and Float Calculator, open the Critical Path Timeline Calculator to find the longest dependent task chain and earliest project completion.
Calculation
Method used
Earliest finish is earliest start plus duration; total and free float use latest finish and successor start.
The Project Slack and Float Calculator evaluates Earliest start day, Activity duration days, and Latest permitted finish day separately; keep Successor earliest start day visible outside any percentage, rate, or total.
Calculation method last reviewed: June 21, 2026.
Worked scenario
Example calculation
Compare Successor earliest start day with the Project Slack and Float Calculator supporting figures before judging the Successor earliest start day headline scale or units.
Visual audit
Reading the supporting metrics
The Project Slack and Float Calculator dashboard places supporting figures beside Earliest start day, Activity duration days, Latest permitted finish day, and Successor earliest start day. Inspect Successor earliest start day in its original unit before accepting the supporting figures or headline status.
Boundaries
Important edge cases and limitations
Multiple calendars, resource leveling, leads, lags, and changing network logic are excluded.
Change Successor earliest start day in the Project Slack and Float Calculator before reading the supporting figures or headline.
Input audit
Checklist for this calculation
- Inspect the Project Slack and Float Calculator period and Earliest start day and Activity duration days units.
- Compare Successor earliest start day with the Project Slack and Float Calculator supporting figures.
- Build a fresh Project Slack and Float Calculator after any Successor earliest start day change.
Practical use
Recommended workflow
Reconcile the result with the full dependency network and project calendar before moving any activity.
Questions
Frequently asked questions
Why can free float be smaller than total float?
A successor can constrain movement earlier than the activity's final permitted finish.
Why should Earliest start day be verified before the project slack and float calculator runs?
Compare Earliest start day with Successor earliest start day inside the Project Slack and Float Calculator reporting basis. Keep the Successor earliest start day unit aligned with the Earliest start day period before reading the headline.
Why is Successor earliest start day worth testing separately in the
Keep Earliest start day and Activity duration days unchanged and change Successor earliest start day once in the Project Slack and Float Calculator. Compare the Successor earliest start day component with supporting figures to identify a proportional or threshold effect.