Seconds Minutes Hours Days
Last reviewed: January 2026
Convert between seconds, minutes, hours, days, weeks, months, and years. This calculator runs entirely in your browser — your data stays private, and no account is required.
Time conversions follow a non-uniform system: 60 seconds per minute, 60 minutes per hour, 24 hours per day, 7 days per week, and varying days per month (28-31). The average month is 30.44 days, and a year averages 365.25 days (accounting for leap years).[1] Common conversions for work and planning: 2,080 work hours per year (40 hrs × 52 weeks), 8,760 total hours per year, and 525,600 minutes per year. These constants appear frequently in salary calculations, project planning, and scientific measurements.[2] For scientific and computing applications, all time reduces to seconds as the SI base unit — Unix timestamps count seconds since January 1, 1970, and physics equations universally use seconds.[3] Use the Unix Timestamp Converter for computing time conversions.
Modern processors operate at billions of cycles per second (GHz = 10⁹ Hz). A 3 GHz processor completes one clock cycle in ~0.33 nanoseconds. Light travels about 1 foot per nanosecond, which limits the physical size of fast computing components. A "Unix timestamp" counts seconds since January 1, 1970 00:00:00 UTC — currently over 1.7 billion. The Y2K38 problem affects systems using 32-bit signed integers to store Unix timestamps: they will overflow on January 19, 2038 at 03:14:07 UTC.
| From | To Minutes | To Hours | To Days |
|---|---|---|---|
| 1 hour | 60 | 1 | 0.0417 |
| 1 day | 1,440 | 24 | 1 |
| 1 week | 10,080 | 168 | 7 |
| 1 month (avg) | 43,800 | 730 | 30.44 |
| 1 year | 525,600 | 8,760 | 365.25 |
Time is the one physical quantity that humans measure using a non-decimal system inherited from ancient Babylon — 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day. This base-60 (sexagesimal) structure makes mental arithmetic harder than with metric units, which is why time conversion calculators remain essential tools even for people comfortable with other unit conversions.
The most frequent time conversions involve moving between seconds, minutes, hours, days, weeks, months, and years. While the relationships between seconds, minutes, hours, days, and weeks are fixed (60, 60, 24, and 7 respectively), months and years introduce variability. A month ranges from 28 to 31 days, and a year is either 365 or 366 days. For engineering and financial calculations, standardized values are often used: a month = 30.4375 days (365.25 ÷ 12) and a year = 365.25 days (accounting for leap years). These averaged values prevent accumulating errors over long time horizons.
One of the most common sources of confusion is converting between decimal hours and hours:minutes format. In decimal, 1.5 hours = 1 hour 30 minutes. But 1.75 hours is not 1 hour 75 minutes — it is 1 hour 45 minutes (0.75 × 60 = 45). Payroll systems frequently use decimal hours (7.25 hours worked), while time clocks display hours:minutes (7:15). The conversion formula is: minutes = decimal fraction × 60. So 8.33 hours = 8 hours and 0.33 × 60 = 19.8 minutes, or approximately 8 hours 20 minutes.
The 24-hour clock eliminates AM/PM ambiguity by counting hours from 0 to 23. Midnight is 00:00, noon is 12:00, 1:00 PM is 13:00, and 11:59 PM is 23:59. To convert PM times to 24-hour format, add 12 to the hour (except 12 PM, which stays 12:00). To convert 24-hour times after 12:00 back to 12-hour format, subtract 12 and add PM. Military time uses the same system without the colon — 0800 (oh-eight-hundred) instead of 08:00. Aviation, medicine, logistics, and most of the world outside the United States use 24-hour time as the standard to avoid scheduling errors caused by AM/PM confusion.
In computing, time is often measured as the number of seconds elapsed since the Unix epoch — January 1, 1970, 00:00:00 UTC. This single integer (e.g., 1783641600 for a date in 2026) provides an unambiguous, timezone-independent reference that simplifies calculations across distributed systems. Converting between Unix timestamps and human-readable dates requires accounting for time zones, daylight saving time transitions, and leap seconds. Most programming languages provide built-in functions for this conversion, but understanding the underlying mechanism helps debug timestamp-related issues in databases, APIs, and log files.
The world is divided into 24 primary time zones, each offset from Coordinated Universal Time (UTC) by whole hours — though several zones use 30 or 45-minute offsets (India at UTC+5:30, Nepal at UTC+5:45, parts of Australia at UTC+9:30). When converting times across zones, add the destination offset and subtract the origin offset from the UTC time. For example, converting 3:00 PM EST (UTC−5) to CET (UTC+1): the difference is 6 hours, so 3:00 PM EST = 9:00 PM CET. Daylight saving time adds complexity — most of the U.S. shifts forward one hour in spring and back in fall, but not all regions observe DST (Arizona, Hawaii, and most U.S. territories do not).
Beyond everyday units, science uses extremely small and large time scales. Milliseconds (10⁻³ seconds) measure network latency and reaction times. Microseconds (10⁻⁶) are relevant to electronics and high-frequency trading. Nanoseconds (10⁻⁹) measure processor clock cycles — light travels about 30 centimeters in one nanosecond. Picoseconds (10⁻¹²) capture molecular vibrations. On the large end, kiloseconds (16.7 minutes) and megaseconds (11.6 days) occasionally appear in scientific literature, though days and years remain standard for human-scale events. A Julian year (exactly 365.25 days) is used in astronomy to define the light-year — the distance light travels in one Julian year, approximately 9.461 trillion kilometers.
Understanding these conversion fundamentals helps in fields from scheduling across time zones to scientific research, software development, and financial calculations where precision timing directly impacts accuracy and outcomes.
The Gregorian calendar (introduced in 1582 and now the global standard for civil use) corrected the Julian calendar's overestimation of the solar year by skipping leap years in century years not divisible by 400 — so 1900 was not a leap year but 2000 was. This correction matters when converting historical dates or calculating durations spanning the Julian-Gregorian transition. Other calendar systems remain in active use: the Hebrew calendar (lunisolar, currently in year 5786), the Islamic calendar (purely lunar, 354–355 days per year, causing dates to shift about 11 days earlier each Gregorian year), and the Chinese calendar (lunisolar, used for determining traditional holidays). Converting between these systems requires specialized algorithms because their month lengths and intercalation rules differ fundamentally from the Gregorian system.
For quick mental math with common conversions: minutes to hours — divide by 60 (or multiply by 0.0167). Hours to days — divide by 24. Days to weeks — divide by 7. Weeks to months — multiply by 0.2299 (approximately). Months to years — divide by 12. For compound conversions, chain the steps: 10,000 minutes = 10,000 ÷ 60 = 166.67 hours = 166.67 ÷ 24 = 6.94 days, or just under one week. When precision matters — payroll, billing, project management, or scientific work — always use exact conversion factors rather than mental approximations, and specify whether you are using calendar months (variable) or standardized 30-day months.
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→ Check the direction of conversion. Make sure you're converting in the right direction. A common mistake is entering the target unit's value in the source field.
→ Use the reference chart. The conversion table below the calculator provides quick lookups for the most common values without needing to enter them individually.
→ Know the key conversion factors. Memorizing a few key ratios (1 inch = 2.54 cm, 1 kg = 2.205 lbs, 1 liter = 0.264 gal) lets you do rough mental conversions on the fly.
See also: Time Zone Converter · Military Time Converter · Time Addition Calculator