Ever seen a product page promise a delivery date that the cut-off had already passed? Full-page caches and CDNs freeze whatever date was calculated when the page was cached. This plugin calculates the estimate in the visitor’s browser, at the moment the page is viewed, so it stays correct behind page caches and CDNs — including right after your cut-off and across daylight-saving changes.

It counts forward from how your store really works: open weekdays, order cut-off, preparation time, carrier transit days and the official holiday calendar (UK bank holidays from GOV.UK, by division, or Japanese national holidays). The result is shown as an estimated range with its basis — never as a guarantee.

Who this is for

If you sell into the UK or Japan, a flat “+5 days” estimate quietly goes wrong: it lands on bank holidays, substitute days and your own closed days, and shows shoppers a date you cannot meet. This plugin works the range out from your actual pattern — open weekdays, preparation time, carrier transit days and the official holiday calendar — and displays it on the product page before checkout, stated as an estimate, never a promise.

How it works

You choose a holiday calendar: UK bank holidays (official GOV.UK data, per division — England & Wales, Scotland, or Northern Ireland) or Japanese national holidays (generated from the statutory rules).
You set your store’s open weekdays, any extra custom closed dates, an order cut-off time, a preparation time in business days, and a transit range in carrier days.
On each product page the plugin counts forward from the moment of viewing: orders before the cut-off start preparation the same business day; later orders start on the next business day. Preparation and transit skip closed days, weekends and holidays on the correct calendar.
The calculation runs in the visitor’s browser at view time (in your site’s timezone), so the dates stay correct even behind full-page caches and CDNs — including right after the cut-off and across daylight-saving changes. Without JavaScript no dates are shown, rather than risk showing a wrong one.
The result is displayed as a range with its basis (“Based on UK bank holidays (England & Wales). Estimate — not a guarantee.”), plus a live “order within X hrs Y mins” countdown when the cut-off is still ahead.

Built-in safety

If a calculation would run past the end of the bundled calendar data, the estimate is hidden entirely and the failure is flagged in wp-admin, instead of showing a date the data cannot support.
A simulator (Tools Delivery Date Simulator) runs the exact storefront calculation — for any order moment, product and (with Pro) destination — and shows the dispatch date, the range, the effective values used, and the day-by-day walk with reasons, including holiday names.
A status panel on the settings page shows the calendar coverage with advance warnings before the data runs out, and settings can be exported/imported as JSON.
The plugin makes no external calls, stores no personal data, and does not read or write orders. All computation happens locally with the bundled calendar data.

Calendars included

United Kingdom: official bank holidays from GOV.UK (bundled snapshot of the GOV.UK data: https://www.gov.uk/bank-holidays.json), 2025–2028, for England & Wales, Scotland and Northern Ireland — including substitute days.
Japan: national holidays 2025–2028 generated from the rules of the Act on National Holidays, including substitute holidays (振替休日) and citizens’ holidays (国民の休日).

How the dates are checked

The UK calendar is a bundled snapshot of the official GOV.UK bank-holiday data — not a hand-typed list — and the Japanese calendar is generated from the rules laid down in the Act on National Holidays, including substitute holidays and citizens’ holidays. The server-side and browser-side calculations are verified against each other across 18 test scenarios, covering daylight-saving weekends, cut-off boundaries in British Summer Time and division-specific holiday exceptions. If a calculated date would fall outside the bundled calendar data (2025–2028), the estimate is hidden rather than guessed. Every estimate is labelled as an estimate, with its calendar basis shown — never as a guaranteed delivery date.

A Pro add-on (sold separately, outside wordpress.org) adds per-product and per-category preparation times, per-shipping-zone transit adjustments, a Royal Mail carrier-holiday layer for the UK, a customer-facing calculation breakdown, and display customisation.

Soroban Delivery Dates for WooCommerce