Week to Decade
wk
dec
Conversion History
| Conversion | Reuse | Delete |
|---|---|---|
1 wk (Week) → 0.00191780821917808219 dec (Decade) Just now |
Quick Reference Table (Week to Decade)
| Week (wk) | Decade (dec) |
|---|---|
| 1 | 0.00191780821917808219 |
| 2 | 0.00383561643835616438 |
| 4 | 0.00767123287671232877 |
| 12 | 0.0230136986301369863 |
| 26 | 0.04986301369863013699 |
| 40 | 0.07671232876712328767 |
| 52 | 0.09972602739726027397 |
About Week (wk)
A week is exactly 7 days (604,800 seconds), a near-universal calendar unit with roots in ancient Mesopotamia and the seven classical celestial bodies visible to the naked eye (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn). The seven-day week is used in virtually every country today, though the day considered the first of the week differs — Monday in the ISO standard and most of Europe, Sunday in the US. Pregnancy is measured in weeks (40 weeks for a full term). Sprint cycles in agile software development are typically 1–2 weeks. News and media cycles operate weekly.
A full-term pregnancy is 40 weeks. A standard work week is 5 days (Monday–Friday). An agile sprint is typically 2 weeks.
About Decade (dec)
A decade is exactly ten years (315,360,000 seconds using the 365-day year convention), used in history, economics, and demography to describe medium-term trends. Decades are culturally significant — the 1920s, 1960s, and 1980s each carry distinct cultural associations. Economic cycles, policy changes, and technology generations are often framed in decade terms. Central bank inflation targets and pension projections span decades. In astronomy, the secular acceleration of the Moon and polar wander are measured in arcseconds per decade.
The smartphone era began roughly two decades ago. A 30-year mortgage spans three decades. Climate projections are typically made in decade increments.
Week – Frequently Asked Questions
Why does a week have 7 days?
The 7-day week was likely first used in ancient Mesopotamia, linked to the 7 classical celestial bodies visible to the naked eye: Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. These gave the days their names (still visible in English: Sun-day, Moon-day, Saturn-day; and in French: Lundi/Moon, Mardi/Mars, Mercredi/Mercury, Jeudi/Jupiter, Vendredi/Venus). The 7-day week spread through Jewish, Roman, and Islamic calendars and eventually became global.
Has any culture used a week shorter or longer than 7 days?
Yes. Ancient Rome used an 8-day market cycle (nundinae). The French Revolutionary calendar used a 10-day decade. The Soviet Union tried 5-day and 6-day continuous work cycles in 1929–1940, eliminating the shared day off to maximize factory output. All alternatives eventually failed: the 7-day week is synchronised with religious practice (Sabbath, Friday prayers, Sunday worship) and is biologically suited to human work-rest rhythms.
Does ISO 8601 start the week on Monday or Sunday?
ISO 8601 defines Monday as the first day of the week (Day 1) and Sunday as the last (Day 7). This is standard across the EU, UK, and most of the world. The US, Canada, Australia, and many Latin American countries traditionally treat Sunday as day 1 — as reflected in US calendars and spreadsheet software defaults. When writing code that spans regions, always check whether the week starts on Sunday (0) or Monday (1).
Why is pregnancy measured in weeks and not months?
Gestational age in weeks is far more precise than months because months have variable lengths. A 36-week pregnancy and a 40-week pregnancy are in different developmental categories (preterm vs. full-term), but both might be described as '9 months.' Clinicians need week-level precision for lung maturity, organ development, and intervention decisions. Ultrasound measurements are calibrated to gestational weeks, not months. The 40-week count begins from the last menstrual period, not conception.
What is the Gregorian calendar rule for how many weeks a year has?
A common year has 52 weeks and 1 day; a leap year has 52 weeks and 2 days. Under ISO 8601, each year has either 52 or 53 numbered weeks (Week 1 is the week containing the year's first Thursday). Years with 53 weeks occur about every 5–6 years. In 2015 and 2020, ISO Week 53 existed. This affects fiscal calendars: companies on a "4-4-5" or "52-week fiscal year" must reconcile the 53rd week when it appears.
Decade – Frequently Asked Questions
Does a decade start in the year ending 0 or 1?
Technically, the first decade CE ran from 1 CE to 10 CE (since there was no year 0), so the 'correct' start of each decade is the year ending in 1 (2021, 2031). However, culturally, decades are named for the tens digit — 'the 1980s' means 1980–1989. Pedants reliably emerge at each decade boundary; the BBC noted in 2000 and 2010 that the millennium/decade technically started one year later. Most people (correctly) ignore this.
What major technology changed every decade in the 20th century?
Each decade introduced a defining technology: 1900s — powered flight; 1910s — mass automobile production; 1920s — radio broadcasting; 1930s — radar; 1940s — nuclear power/weapons; 1950s — television; 1960s — satellite communication; 1970s — microprocessors; 1980s — personal computers; 1990s — the World Wide Web; 2000s — smartphones; 2010s — social media. Each took roughly a decade to reach mass adoption — a pattern noted by technology historians as the 'decade diffusion' cycle.
Why do economists talk about "lost decades"?
A 'lost decade' describes a 10-year period of economic stagnation or decline. Japan's 1990s is the canonical example — following a 1989 asset bubble collapse, GDP growth was near zero for 10+ years. The US 2000s was described as a 'lost decade' for stock market returns (the S&P 500 ended 2009 below its 2000 start). Decades are a natural framing for these assessments because they align with business cycles, political cycles, and generational economic memory.
What is the Saros cycle and how does it relate to decades?
The Saros cycle is 18 years, 11 days, and 8 hours (approximately 1.8 decades) — the period after which the Sun, Earth, and Moon return to almost identical relative geometry, causing near-identical eclipses. Ancient Babylonians discovered this cycle around 600 BCE and used it to predict lunar eclipses. NASA uses the Saros series to catalog eclipses: each eclipse is numbered within its Saros series, which lasts about 1,300 years (roughly 130 decades).
How long does it take for fashions to "come back" — is it really a decade?
Fashion cycles have been studied empirically and do show roughly 20-30 year revival patterns — not exactly one decade. Styles become unfashionable, then nostalgia peaks when the generation that wore them reaches their 30s–40s and has disposable income. 1990s fashion revived in the 2010s; 1970s styles returned in the 1990s and 2010s. The "20-year rule" is a reasonable approximation, though fast fashion and social media are compressing cycles significantly.