Choose the boundary
Decide whether the start and end can count instead of relying on a silent default.
Business-day arithmetic you can inspect
Clear deadlines start with clear rules.
Add, subtract, or count business days. DueRule shows the boundary choice, every skipped date, every reason, and the exact calendar revision behind the answer.
Free calculatorNo accountNo tracking
Free · no sign-in · no tracking
Calculate with the rule in view
Result
Rule and source details
The answer and the path to it.
Deadline tools should not hide their assumptions. DueRule keeps correctness and provenance on the free side of the product.
Inspect every skip
Weekends and closures appear in order. Overlapping reasons stay visible without double-counting the date.
Verify the source
Sourced profiles expose coverage, revision, rules hash, and engine version alongside the result.
Start with the calculation you need.
Each guide gives a direct calculator, plain-language boundary guidance, and links back to the methodology.
Deadline
Add business days
Move forward by an exact number of working days.
Add business days →Lookback
Subtract business days
Move backward while retaining the full exclusion trace.
Subtract business days →Duration
Count between dates
Control both boundaries and count eligible dates in a forward range.
Count business days →Questions people ask.
These answers describe the calculator’s visible behavior, not legal rules for a particular deadline.
What does a business day calculator count?
DueRule counts dates allowed by the selected workweek and removes each matching closure once, while showing every exclusion reason.
Does DueRule include federal holidays?
The OPM Nationwide and OPM DC Area profiles contain exact materialized dates for 2024 through 2027. DueRule blocks sourced calculations outside that verified coverage.
Is the calculator free?
Yes. Add, subtract, between calculations, boundary controls, all built-in profiles, provenance, and the complete trace are free without an account.