Time Converter

Quick Reference Table

From	To	Multiply By	Example
Seconds	Minutes	÷ 60	120 sec = 2 min
Minutes	Hours	÷ 60	120 min = 2 hrs
Hours	Days	÷ 24	48 hrs = 2 days
Days	Weeks	÷ 7	14 days = 2 weeks
Weeks	Months	÷ 4.345	4 weeks ≈ 0.92 months
Years	Days	× 365.25	1 year = 365.25 days
Milliseconds	Seconds	÷ 1000	5000 ms = 5 sec
Microseconds	Milliseconds	÷ 1000	5000 μs = 5 ms

Time Unit Equivalents

Unit	In Seconds	Common Uses
Nanosecond	0.000000001 s	Computer processors, light travel
Microsecond	0.000001 s	Electronics, high-speed photography
Millisecond	0.001 s	Computing, reaction times
Second	1 s	SI base unit, everyday timing
Minute	60 s	Short durations, appointments
Hour	3,600 s	Work shifts, travel time
Day	86,400 s	Earth rotation, schedules
Week	604,800 s	Work cycles, planning
Month (avg)	2,629,800 s	Calendars, billing cycles
Year	31,557,600 s	Earth orbit, age, planning

Understanding Time Units

Nanosecond (ns)

Definition: One billionth of a second (0.000000001 s or 10⁻⁹ s). Light travels approximately 30 centimeters (1 foot) in one nanosecond.

History: Emerged with precise atomic clocks and high-speed electronics in the mid-20th century. Named using the SI prefix "nano-" meaning one-billionth.

Current Use: Critical in computer processors (CPU clock cycles measured in nanoseconds), network latency, GPS satellite timing, particle physics, telecommunications, and high-frequency trading. Modern CPUs execute instructions in a few nanoseconds.

Microsecond (μs)

Definition: One millionth of a second (0.000001 s or 10⁻⁶ s). There are 1,000 microseconds in a millisecond.

History: Became relevant with electronic timing devices and high-speed photography in the early-to-mid 20th century.

Current Use: Used in electronics engineering, oscilloscopes, laser pulse measurements, strobe photography, sound wave analysis, and computer memory access times. DRAM memory access takes microseconds.

Millisecond (ms)

Definition: One thousandth of a second (0.001 s or 10⁻³ s). There are 1,000 milliseconds in one second.

History: Standardized with the metric system. Became important for measuring human reaction times, film frame rates, and later computer response times.

Current Use: Extensively used in computing (website load times, ping/latency), video frame rates (film runs at 24 fps = 42 ms per frame), human reaction time measurements, audio processing, gaming (frame time), and sports timing. Human eye blink takes 100-150 ms.

Second (s)

Definition: The SI base unit of time. Since 1967, defined as exactly 9,192,631,770 cycles of radiation from the cesium-133 atom. Historically based on Earth's rotation (1/86,400 of a day).

History: Ancient civilizations divided the day into smaller units. Medieval scholars divided hours into 60 minutes and minutes into 60 seconds (from Latin "secunda," meaning second division). Modern atomic definition ensures unprecedented accuracy.

Current Use: Universal time measurement in daily life, science, sports, cooking, and all aspects of human activity. Standard unit for stopwatches, timers, and time displays worldwide.

Minute (min)

Definition: Exactly 60 seconds. One minute equals 1/60 of an hour or 1/1,440 of a day.

History: Originated with ancient Babylonian base-60 number system. The word comes from Latin "pars minuta prima" (first small part), referring to the first division of the hour.

Current Use: Used globally for short time measurements, appointments, cooking times, meeting durations, exercise timing, and public transportation schedules. Standard unit for expressing short to medium durations.

Hour (hr or h)

Definition: Exactly 60 minutes or 3,600 seconds. One hour equals 1/24 of a day.

History: Ancient Egyptians divided daylight and darkness into 12 hours each. Greeks and Romans adopted this system. Hour became standardized at 60 minutes with mechanical clocks in the 14th century.

Current Use: Primary unit for work shifts, travel time, class periods, business hours, and time zone differences. Used in speed calculations (miles per hour, kilometers per hour) and rate measurements (dollars per hour).

Day (d)

Definition: Exactly 24 hours, 1,440 minutes, or 86,400 seconds. Based on Earth's rotation period.

History: One of the oldest time units, based on the cycle of daylight and darkness. Ancient civilizations used days for calendars and agricultural planning.

Current Use: Fundamental unit for calendars, schedules, deadlines, and date tracking worldwide. Used in weather forecasts, project planning, rental periods, and age calculations (birthdays).

Week (wk)

Definition: Exactly 7 days, 168 hours, or 604,800 seconds. Not directly based on astronomical cycles.

History: Likely originated with ancient Babylonians and Biblical creation story (7 days). Adopted by many cultures including Romans (named after celestial bodies: Sunday/Sun, Monday/Moon, etc.).

Current Use: Standard work cycle (5-day workweek, weekend), school schedules, pay periods, TV programming cycles, and short-term planning. Universal across most cultures despite having no astronomical basis.

Month

Definition: Varies: 28-31 days depending on the month. Average month = 30.44 days (365.25 ÷ 12). Originally based on lunar cycles (29.5 days).

History: Derived from "moon" cycles. Ancient calendars followed lunar months. Roman calendar was reformed by Julius Caesar (Julian calendar) and later Pope Gregory XIII (Gregorian calendar, 1582), creating months of varying lengths.

Current Use: Primary calendar unit for billing cycles, rent, subscriptions, salaries, budgeting, and long-term planning. Standard time frame for business and financial reporting.

Year (yr or y)

Definition: Approximately 365.25 days (accounting for leap years). One complete Earth orbit around the Sun. Precisely 31,557,600 seconds on average.

History: Based on seasonal cycles observed by agricultural societies. Modern Gregorian calendar (1582) accurately tracks Earth's orbit with leap years every 4 years (except century years not divisible by 400).

Current Use: Fundamental for calendars, age, historical dates, financial years, academic years, contracts, warranties, and long-term planning. Used in astronomy (light-years measure distance light travels in one year).

Decade, Century, Millennium

Decade: 10 years. Century: 100 years. Millennium: 1,000 years. Used for historical periods, long-term trends, and generational references.

Frequently Asked Questions

How many seconds are in a day?

There are exactly 86,400 seconds in one day. Calculation: 24 hours × 60 minutes × 60 seconds = 86,400 seconds. This is a constant value used for timekeeping worldwide.

How many days are in a year?

365 days in a common year, 366 in a leap year. Average: 365.25 days (accounting for the leap year cycle). Leap years occur every 4 years (divisible by 4), except century years must be divisible by 400. So 2000 was a leap year, but 1900 was not.

How do I convert hours to seconds?

Multiply hours by 3,600 (60 minutes × 60 seconds). Formula: seconds = hours × 3,600. Example: 2 hours × 3,600 = 7,200 seconds. To convert seconds to hours, divide by 3,600.

Why are there 60 seconds in a minute and 60 minutes in an hour?

Inherited from ancient Babylonians who used a base-60 (sexagesimal) number system around 3000 BCE. They chose 60 because it's divisible by many numbers (2, 3, 4, 5, 6, 10, 12, 15, 20, 30), making calculations easier without decimals.

How many weeks are in a year?

52 weeks plus 1 day (52.14 weeks precisely). Calculation: 365 days ÷ 7 days/week = 52.14 weeks. In leap years, it's 52 weeks plus 2 days. This is why calendar dates shift by one day each year.

What is a leap second?

An occasional one-second adjustment to UTC (Coordinated Universal Time) to keep atomic clocks synchronized with Earth's slowing rotation. Leap seconds are added (or theoretically removed) as needed, typically at the end of June or December. About 27 have been added since 1972.

How many milliseconds are in a second?

Exactly 1,000 milliseconds in one second. "Milli" means one-thousandth, so 1 second = 1,000 milliseconds = 1,000,000 microseconds = 1,000,000,000 nanoseconds.

Why isn't there a decimal time system?

Several attempts have been made (French Revolution tried 10-hour days). However, 60 is mathematically superior for division than 10 or 100. The 24-hour day and 60-minute hour are deeply embedded in global infrastructure, culture, and technology, making change impractical despite metric system success elsewhere.

Common Uses for Time Conversion

• Project Management: Converting work hours to days or weeks for scheduling
• Cooking & Baking: Converting recipe times between seconds and minutes
• Science & Research: Converting experimental durations to standard units
• Computing: Understanding milliseconds for performance optimization
• Fitness & Training: Converting workout durations and intervals
• Age Calculations: Converting years to days or seconds
• Travel Planning: Converting flight times across time zones
• Contract Terms: Converting weeks, months, and years for agreements

Interesting Time Facts

• Human heartbeat: ~70 beats per minute = 1.17 beats per second
• Average human lifespan: ~80 years = 2.5 billion seconds
• Blink of an eye: 100-150 milliseconds
• Hummingbird wingbeat: 50-80 times per second
• Earth's rotation is slowing: days were 23 hours long 600 million years ago
• Atomic clocks: accurate to 1 second in 100 million years
• Internet traffic: measured in milliseconds (ping under 20 ms is excellent)
• Light from Sun reaches Earth: 8 minutes 20 seconds
• Age of Universe: ~13.8 billion years = 435 quintillion seconds
• Planck time: 5.4 × 10⁻⁴⁴ seconds (smallest meaningful time unit)

Time Conversion Tips

1. Remember key multiples: 60 sec/min, 60 min/hr, 24 hrs/day, 7 days/week
2. Quick day calculation: 1 day = ~86,400 seconds (easy to remember: 86.4k)
3. Year approximation: 365.25 days (accounts for leap years)
4. Month average: 30.44 days (365.25 ÷ 12)
5. Milliseconds matter: In computing, 100ms delay is noticeable to users
6. Use proper abbreviations: s (seconds), min (minutes), h or hr (hours)
7. Leap year check: Divisible by 4, except centuries must be divisible by 400

Time Measurement in History

Time measurement evolved from astronomical observations to atomic precision:

• 3000 BCE: Sundials used in Egypt and Babylon
• 1500 BCE: Water clocks (clepsydra) invented
• 14th century: Mechanical clocks with hour hands
• 1656: Pendulum clock invented by Christiaan Huygens
• 1884: Greenwich Mean Time established as world standard
• 1949: First atomic clock developed
• 1967: Second redefined using cesium atomic standard
• Today: GPS satellites use atomic clocks accurate to nanoseconds