About Business Day Calculator

Who built this and why

BusinessDayCalculator.org was built by Barron Hansen, a web developer and CRM customization specialist with 25 years of work building tools for businesses to manage operations, contracts, and client billing. The site grew out of a recurring need on client projects: counting working days correctly across CRM workflows, invoice scheduling, and project deadlines for clients operating across multiple countries.

The recurring problem was that off-the-shelf calculators almost always handled one country well and handled the rest poorly. A US calculator did not know that UK Christmas creates a Tuesday substitute when 25 December lands on a Sunday. A UK calculator did not handle Indian Diwali. A spreadsheet formula could be coaxed into doing the math but had to be rebuilt for each new country added to a client's footprint. Building a single tool that handled the full set was easier than rebuilding the same logic project after project.

The site is a SquarepegIdeas project. SquarepegIdeas is the parent studio for several practitioner-built calculators and reference tools, all freely available with no signup required and no data collected from users.

What this tool does

BusinessDayCalculator.org is a free, browser-based calculator for working out business days. You can calculate the number of business days between two dates, add or subtract working days from a start date, or find the exact due date for payment terms like Net 30, Net 60, and Net 90. The calculator handles weekends and public holidays automatically.

All calculations run entirely in your browser. No dates you enter are ever sent to a server. There's no account to create, no login required, and no data stored about you.

Why we cover 11 countries

The original six countries (US, UK, Canada, Australia, India, Philippines) were chosen for English-language B2B reach. Most outsourced services billing, freelance contract work, and multinational vendor management runs through these jurisdictions, so the calculator started where the demand was.

Germany, France, Japan, Singapore, and Mexico were added later for users running multinational teams and supply chains where these countries appear regularly. The selection is not exhaustive; if you need a country we do not cover, the Advanced options section of each calculator accepts custom holiday dates that get merged with the country list.

For full details on what holidays are included for each country, how observed dates are handled, and how lunar and Islamic calendar dates are computed, see the holiday data methodology page.

How we maintain accuracy

Holiday data is reviewed annually as official calendars publish for the following year, typically November and December. Proclamation-driven dates (Philippine Eid'l Fitr, Singapore Hari Raya, Indian gazette holidays) are updated as the relevant ministries publish them, usually in October through December for the following year.

Coverage extends three years forward from the current date. The same dataset feeds every calculator on the site, so a correction filed against the US holiday data updates the US calculator, the general business-day calculator, the year and month reference pages, and the country-specific calculator simultaneously.

If you find an error, please get in touch. Include the country, the date, and the source you are referencing. Corrections are typically published within a few days of confirmation.

Who uses this tool

Business day calculations come up across a range of working roles:

• Freelancers and contractors tracking Net 30 or Net 60 payment terms on invoices
• Accounts payable and receivable teams managing payment due dates across multiple vendors
• Project managers planning delivery timelines and sprint cycles in business days
• HR professionals calculating employee notice periods, payroll cycles, and leave entitlements
• Lawyers and paralegals calculating response deadlines, filing windows, and statutory notice periods
• Customer support and operations teams tracking SLA response and resolution deadlines
• Small business owners managing contract timelines and supplier payment schedules

What we plan to add

Planned work over the next several quarters includes additional reference guides, more long-form country pages with month-level breakdowns, and a small set of additional calculators for adjacent workflows (escrow timing, contract renewal windows). Country additions are evaluated as user demand and source data quality permit. We do not promise specific dates because the work runs alongside client projects.

About SquarepegIdeas

BusinessDayCalculator.org is a project by SquarepegIdeas, a small product studio based in Texas. Other tools in the SquarepegIdeas portfolio are listed in the footer of every page.

Questions, feedback, or holiday data corrections: hello@businessdaycalculator.org