Days of the Week: Names, Order, Origins & Kids Songs

Ask a child to sing the days of the week and they’ll usually get it right—then ask them why Friday is called Friday, and you’ll hear crickets. The names hiding in plain sight on every calendar carry a 4,000-year history, blending Roman gods, Norse thunderbolts, Babylonian stargazers, and even a Hebrew Sabbath. This guide sorts out the seven days, their correct order, where those names actually came from, and which kid-friendly songs make the learning stick.

Days in a week: 7 · ISO 8601 first day: Monday · Average weeks per year: 52.142 · Name origins: Planets and gods · Popular kids song channel: Super Simple Songs

The table below consolidates the core facts about the seven-day week system and how English adopted it.

What are the 7 days of the week?

The seven days run Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday. English keeps it simple—no numbers, no exceptions—though the origins behind each name are anything but straightforward.

Standard names

Every English speaker knows the seven names, but the pattern beneath them rewards a closer look. Three days trace back to celestial bodies (Sun, Moon, Saturn), while four others carry the names of Germanic and Norse gods who replaced their Roman counterparts. Britannica explains that Tuesday switched Mars for Tyr, Wednesday swapped Mercury for Odin, Thursday traded Jupiter for Thor, and Friday surrendered Venus to Frigg (Britannica). Saturday alone stayed loyal to the Roman tradition, keeping Saturn instead of adopting a Germanic equivalent.

Common abbreviations

• Sun. / Sun
• Mon. / Mon
• Tue. / Tue
• Wed. / Wed
• Thu. / Thu
• Fri. / Fri
• Sat. / Sat

What is the correct order for the days of the week?

The answer depends on who’s asking, because two competing traditions have shaped the modern calendar.

ISO 8601 standard

The international ISO 8601 standard designates Monday as the first day of the week—a convention adopted by most of Europe, Asia, and the business world (Wikipedia). This ordering reflects the post-war push for standardized global calendars, prioritizing work-week continuity over religious tradition.

Cultural variations

In the United States, Sunday traditionally opens the week, a practice rooted in Constantine’s 321 AD decree that made Sunday the first day and a day of rest (Britannica). Jewish and Sabbath-observant traditions count Saturday as the seventh day, making it the natural endpoint rather than the start. Teachers Pay Teachers materials for kids typically begin with Sunday, matching the US calendar convention most American children encounter in school (Teachers Pay Teachers).

Did God create the 7 day week?

The seven-day structure appears in the Genesis creation narrative, but the calendar predates that text by millennia—suggesting the Bible adopted an existing convention rather than inventing one.

Biblical origins

The Book of Genesis describes God creating the world in six days and resting on the seventh, establishing the Sabbath as a sacred institution (Wikipedia). Early Judaism adopted this seven-day rhythm, and when Christianity spread through the Roman Empire, it carried the Sabbath structure with it. Constantine, as a Christian convert, formally enshrined Sunday as the day of rest and worship in 321 AD (Britannica).

Historical development

Yet the Sumerians were using a seven-day cycle around 2100 BC—roughly 1,500 years before the Genesis text was written (Live Science). The Babylonians inherited and elaborated this system, linking each day to one of seven celestial bodies: Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn (Live Science). The number 7 held sacred significance to them, possibly tied to lunar phases spanning approximately 29.53 days (Live Science).

How many weeks are there in a year?

A non-leap year contains 365 days; dividing by 7 gives 52 weeks plus 1 day. Leap years add a second bonus day, making 52 weeks plus 2 days. On average, that’s 52.142 weeks per year.

Average count

Britannica confirms that 52 weeks plus 1 day is the standard breakdown for most years (Britannica). This remainder is why your birthday occasionally lands on a different day of the week from the previous year.

Leap year effects

During leap years, February gains an extra day, pushing the total to 366. The additional day shifts the entire subsequent calendar forward by one—March 1st lands on a different weekday than it would in a non-leap year, affecting payroll cycles, school schedules, and project timelines that rely on week-based accounting.

Week 53 cases

Some calendar systems and accounting standards recognize a 53rd week when the year doesn’t divide cleanly into 52 equal portions. ISO week-date systems handle this by extending Week 52 or introducing Week 53 to maintain Monday-start alignment. This anomaly affects industries using 4-4-5 retail accounting or academic semesters structured around full weeks.

What are popular days of the week songs for kids?

Songs transform abstract sequence into muscle memory. The repetitive melody and rhythm help children internalize the order before they understand why each name exists.

Super Simple Songs

Super Simple Songs has become the dominant resource for early childhood educators learning the days of the week. Their “Days of the Week” video uses simple choreography and clear enunciation, with the full sequence: “Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday.” The channel’s animated puppet versions keep preschoolers engaged through repeated viewing.

Singing Walrus

The Singing Walrus targets kindergarten through early elementary (ages 5–8) with educational songs built around memorize-first pedagogy. Their “Days of the Week Song” repeats the sequence multiple times per verse, using a call-and-response structure where the narrator sings the days and invites children to join. The educational design prioritizes retention over depth, making it effective for pure memorization.

The Learning Station

The Learning Station (Discovery Education) approaches the days as part of broader calendar and seasonal vocabulary sets. Their songs integrate day names with months and weather vocabulary, suitable for classroom settings building comprehensive time-orientation skills rather than isolated day memorization.

How do other languages name the days?

English’s mixed Roman-Germanic system is unusual. Most languages commit fully to either the planetary system or the numbered system.

Romance languages

Spanish, French, and Italian retained Latin planetary names for Monday through Friday—but shifted Sunday and Saturday to religious terms. Spanish uses domingo (Lord’s Day) and sábado (Sabbath) (Wikipedia). Portuguese and Mirandese take a hybrid approach, using numbered weekdays (segunda-feira, terça-feira) for most of the week while keeping sábado and domingo for weekends (Wikipedia).

Germanic languages

German retains the celestial-norse blend but with quirks. Mittwoch means “mid-week” rather than deriving from Mercury, while Samstag and Sonnabend represent different regional preferences for Saturday naming (Duolingo language blog). Danish uses similar Norse god mappings but names Saturday lørdag, meaning “bath day” from Old Norse—a completely different etymology than English Saturday (Viking Ship Museum historical record).

Arabic, Greek, and other systems

Arabic uses al-ahad (the first day) for Sunday and al-jum’a (day of assembly) for Friday, reflecting the Islamic Friday prayer tradition (Duolingo language blog). Greek calls Friday Paraskeví, meaning “preparation” for the Sabbath (Duolingo language blog). Indic languages name days after Sanskrit deities corresponding to the same celestial bodies (Duolingo language blog).

Constantine, a convert to Christianity, decreed that Sunday should be a day of rest and worship. — Britannica encyclopedia editors

We have the Babylonians to thank for the 7-day week with names after the celestial bodies and gods. — Educational YouTube narrator

The seven-day week has outlasted empires, religious revolutions, and calendar reforms. It began with Sumerian lunar observations, passed through Babylonian celestial theology, survived Roman indifference, received Constantine’s imperial seal, and arrived at your smartphone home screen unchanged. The names carry that history in plain sight—Mars fighting Tuesday as Tyr, Jupiter rumbling Thursday as Thor, Venus softened Friday as Frigg. Children absorb this inheritance through songs before they encounter it in classrooms, making melody an unlikely carrier of ancient linguistics.