Business Day Adder (Add or Subtract Working Days)
A calendar-day count and a business-day count are different numbers, and confusing them is the kind of small mistake that lands a contract ten days late or a court filing past its deadline. Net-30 payment terms, two-business-day shipping promises, four-week SLA targets, 30-day cure periods in commercial leases — every one of those depends on a working-day count that skips weekends and skips the public holidays the parties recognize. This tool runs that calculation in your browser, with bundled holiday calendars for the four English-speaking jurisdictions that drive the bulk of practical use.
Why Business Days Are Not Calendar Days
A calendar-day count is straightforward: today plus thirty is the date that lands on the calendar thirty rows down. A business-day count is straightforward in principle and full of edge cases in practice. Saturdays and Sundays do not count, which already drops the effective workday count to roughly 71% of the calendar count. Public holidays compound the effect: a US ten-business-day SLA crossing late November will quietly absorb Thanksgiving and the Friday after, while a UK calculation in early May will absorb the early May bank holiday and possibly the spring bank holiday a few weeks later. In contracts where the working-day count is the operative deadline, mishandling either step produces a date that is wrong by anywhere from one to four days depending on the period.
How the Tool Handles Holiday Calendars
The tool ships with four bundled jurisdictions: the United States (federal observed holidays, eleven days a year), the United Kingdom (bank holidays for England and Wales, with separate notes for Scotland and Northern Ireland), Canada (federal holidays plus the day-in-lieu rule), and Australia (national public holidays). Each is loaded as a static date list for 2024 through 2027, regenerated annually. Observed-day rules are pre-applied — if July 4 falls on a Saturday, the bundled US list reflects that the observed federal holiday is the preceding Friday. Layering is additive: you can pick one jurisdiction, multiple jurisdictions (useful for multi-country teams where the latest holiday across regions is the operative skip), or none (weekends-only mode, useful for purely-domestic settings where you maintain holidays elsewhere).
Use Cases That Justify a Working-Day Calculation
Net-30 invoice payment terms are the most common case — thirty business days from invoice date is the standard payable target for most B2B contracts, and a working-day count is what the accounts payable team actually meets, not the calendar-day count the contract literally specifies. Shipping ETAs are the next most common: two-day shipping is two business days, not two calendar days, which is why a Friday-evening order arrives Tuesday rather than Sunday. Court filing deadlines almost always count in working days within the jurisdiction's calendar, including state-specific holidays that the bundled US list does not always cover — in those cases use the multi-jurisdiction mode or fall back to weekends-only and validate against the court's own calendar. SLA targets, regulatory response windows, and lease cure periods all sit in the same family.
What the Tool Does Not Do
Half-day holidays and partial-day closures (Christmas Eve early-close, US federal half-day before certain holidays) are treated as full working days here — the bundled lists track only full closures. Religious and observance holidays beyond the public-holiday set are not included; if your contract operates on a different calendar (Islamic, Jewish, Lunar New Year for non-public-holiday jurisdictions) you will want to layer those manually or compute against weekends-only. Floating holidays (the day after Thanksgiving in the US is by convention a closure but is not a federal holiday) are included where they are observed widely; the tool documents which floating days it counts so you can adjust expectations. Time-of-day cutoffs (a Friday-after-3pm order ships Monday at the carrier's discretion) are out of scope — this is a date-level tool, not an order-handling system.
Pair this with related UDT planning tools: Age Calculator for date-of-birth or date-difference math, Timestamp Converter for unix-time and ISO-8601 conversion, and Cron Next Fire for cron-expression scheduling. The four together cover most of the small calendar-math gaps that come up around contracts, shipping, billing, and scheduled jobs.
Frequently Asked Questions
Built by Derek Giordano · Part of Ultimate Design Tools