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Japan Public Holidays Calculator

Japan's national holidays for any year, calculated live — including several deliberately shifted to always land on a Monday.

The "Happy Monday System"

Since a set of reforms starting in 2000, Japan deliberately defines several holidays as "the Nth Monday of [month]" rather than a fixed date, specifically to guarantee a long weekend every time — Coming of Age Day, Marine Day, Respect for the Aged Day, and Health and Sports Day are all defined this way. It's a rare example of a country explicitly redesigning its holiday calendar around creating three-day weekends rather than tradition or religious observance.

The substitute holiday rule

If a fixed-date holiday falls on a Sunday, the following Monday becomes a substitute holiday (furikae kyujitsu) — similar in spirit to the UK's substitute-day system, but specifically triggered by a Sunday collision rather than any weekend day.

Related

Related tools

India Public Holidays Calculator

Another Asian calendar, with its own mix of fixed and lunar-based dates.

Current Time in Tokyo

Check the current time alongside the holiday calendar.

Nth Weekday of the Month Finder

The exact logic behind every Happy Monday holiday.

function nthWeekday(year, month, weekday, n){ if(n === -1){ const last = new Date(Date.UTC(year, month+1, 0)); let d = last.getUTCDate(); while(new Date(Date.UTC(year, month, d)).getUTCDay() !== weekday) d--; return new Date(Date.UTC(year, month, d)); } const first = new Date(Date.UTC(year, month, 1)); const offset = (weekday - first.getUTCDay() + 7) % 7; return new Date(Date.UTC(year, month, 1 + offset + (n-1)*7)); } function japanHolidays(year){ const raw = [ ['New Year\'s Day', new Date(Date.UTC(year,0,1))], ['Coming of Age Day', nthWeekday(year,0,1,2)], ['National Foundation Day', new Date(Date.UTC(year,1,11))], ['Emperor\'s Birthday', new Date(Date.UTC(year,1,23))], ['Showa Day', new Date(Date.UTC(year,3,29))], ['Constitution Memorial Day', new Date(Date.UTC(year,4,3))], ['Greenery Day', new Date(Date.UTC(year,4,4))], ['Children\'s Day', new Date(Date.UTC(year,4,5))], ['Marine Day', nthWeekday(year,6,1,3)], ['Mountain Day', new Date(Date.UTC(year,7,11))], ['Respect for the Aged Day', nthWeekday(year,8,1,3)], ['Health and Sports Day', nthWeekday(year,9,1,2)], ['Culture Day', new Date(Date.UTC(year,10,3))], ['Labor Thanksgiving Day', new Date(Date.UTC(year,10,23))], ]; return raw.map(([name,date]) => ({name, date})); } const now = new Date(); for(let y = now.getFullYear()-1; y <= now.getFullYear()+3; y++){ const opt = document.createElement('option'); opt.value = y; opt.textContent = y; if(y === now.getFullYear()) opt.selected = true; document.getElementById('hlYear').appendChild(opt); } const yearSelect = document.getElementById('hlYear'); const table = document.getElementById('hlTable'); function fmt(d){ return d.toLocaleDateString('en-US',{weekday:'short', month:'long', day:'numeric'}); } function render(){ const year = parseInt(yearSelect.value,10); const rows = japanHolidays(year); table.innerHTML = rows.map(r => `
${r.name}${fmt(r.date)}
`).join(''); } yearSelect.addEventListener('change', render); render();