Business Days Calculator
Add business days to a date — Saturdays and Sundays skipped, the landing day named, the calendar cost of the weekend counted.
Business Days Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Weekend-only skipping — no holiday calendar
- Forward walks only, whole days
In short: Ten business days from Friday 18 September 2026 is Friday 2 October 2026 — fourteen calendar days carrying ten of them, because four weekend days stood in the way and were stepped over. A business week is five days wearing a seven-day coat: every five business days costs a full calendar week, and the remainder decides whether the landing crosses another weekend. Public holidays are a map, not a formula, and this page does not pretend to own one.
Formula
walk day by day; count only Mon–Fri until n is paid
There is no closed form that stays honest, so the arithmetic walks the calendar one day at a time, counting only the days whose weekday is Monday through Friday, until the count is paid. The weekend days it stepped over are reported — that is the calendar cost. Five business days always consume seven calendar days or more, never fewer; the remainder's position decides how many extra weekend days ride along.
Worked Example
- Set the start date.
- Name the business days to spend.
- Read the landing and what the weekends cost.
Defaults: ten business days from Friday 18 September — lands Friday 2 October, fourteen calendar days, four weekend days skipped. Twenty days lands a fortnight further on with eight skips.
Strengths & Limits Of This Model
Where this engine is strong
- The weekend toll is counted, not absorbed
- Landing is always a weekday, by construction
Where it stops
- Holidays unknown — the floor, not the promise
Practical Use Cases
Settlement dates
trade plus the standard run
Notice periods
the day notice takes effect
Lead times
supplier days that mean weekdays
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Business Days Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What counts as a business day here?
Monday through Friday, nothing more. Saturday and Sunday are skipped in every jurisdiction that rests on the weekend; which other days are dark is a local question the page cannot see.
Where are the public holidays?
Deliberately absent. Every country, state and industry carries its own list, and a wrong holiday is worse than an honest omission — count them yourself and add a day per holiday inside the span. The landing here is the no-holiday floor.
Why does five business days take seven calendar days?
Because the working week is five of the calendar's seven. The two spare days are the weekend, and the arithmetic pays them no wages — it just steps over them and reports the toll.
Does the start day count?
No — the walk begins the day after the start, which matches how lead times and notice periods are spoken: ten business days from Friday means the tenth counted weekday after it.
What if the landing itself is a weekend?
It cannot be — the walk only stops on a weekday, so the landing is always a Monday through Friday. If your rule rolls results off holidays too, add those days by hand from here.
Why not just divide by five and multiply by seven?
Because the remainder lands differently depending on where in the week the start sits — a formula that ignores the start's weekday is wrong half the time. The walk is the only arithmetic that is right every time, which is why it is the one used.
Can I run it backwards?
Not on this panel — it adds forward only. To reverse, use the working-days page to see how many business days a calendar span contains, and walk back by that count from the later date.
Half-days and short Fridays?
Out of scope — a business day here is a whole one. Reduced hours change what fits inside a day, not how many days exist; count the days here and let the rota price the hours.