PhysicsCalcs
Units & Conversions

Time Converter

Convert seconds to minutes, minutes to hours, milliseconds to seconds, days to years, Julian year, sidereal day, Planck time, and more.

Interactive converter

Time Converter

Convert seconds, milliseconds, minutes, hours, days, weeks, years, decades, sidereal time, Planck time, and more.

This tool converts durations, not time zones or calendar dates. Months and years are definition-dependent — check unit labels.

From
To

Result

Enter a value and click Convert to see the conversion.

Quick Guide

  • Enter a duration and select units.
  • Calendar and astronomical units are labeled — check which year or month type is used.
  • Not for timezone or date arithmetic.

Table of Contents

Key Takeaways

  • The second is the SI base unit of time.
  • 1 minute = 60 s; 1 hour = 3,600 s; 1 day = 86,400 s.
  • Months and years are definition-dependent — the unit type must be stated.
  • This converter handles durations, not time zones or calendar dates.

What Is a Time Converter?

It converts time durations between SI, everyday, calendar, astronomical, and scientific units using seconds internally. Useful for physics, engineering, astronomy, and coding.

Pair with the Speed Converter for speed = distance/time problems, or the RC Time Constant Calculator for RC circuit time constants.

How to Use the Time Converter

  1. 1Enter a duration (e.g. 3600 or 1e-3 for milliseconds).
  2. 2Choose from and to units — calendar units show their definition in the label.
  3. 3Click Convert; results scroll into view automatically.
  4. 4Use All units mode to see every equivalent at once.
  5. 5Check sidereal vs solar units when working in astronomy.

Time and the SI Second

1min=60s⋅1h=3,600s⋅1d=86,400s1 min = 60 s · 1 h = 3,600 s · 1 d = 86,400 s

The second is the SI base unit. Metric prefixes scale from yoctoseconds to teraseconds.

Common Time Units

UnitSeconds
minute60
hour3,600
day86,400
week604,800

Milliseconds and Smaller

Milliseconds appear in web performance; microseconds and nanoseconds in electronics; femto- and attoseconds in ultrafast science.

Months and Years Are Not Always Fixed

Common year = 365 d; leap year = 366 d; Julian year = 365.25 d; Gregorian average = 365.2425 d. Always specify which definition you use.

Astronomical Time Units

Sidereal day ≈ 86,164.0905 s (with hour, minute, and second subdivisions). Synodic month ≈ 29.530588853 days. Tropical and sidereal years differ slightly — both are approximate. Sidereal day × 365 ≠ sidereal year due to Earth's orbital motion.

Scientific Time Units

Shake = 10 ns. Planck time ≈ 5.39×10⁻⁴⁴ s. Atomic unit of time from CODATA.

Time Duration vs Clock Time

This tool converts elapsed durations. It does not convert UTC to local time, legal timestamps, or calendar dates. Not for timezone or daylight-saving arithmetic.

Examples

1 hour

1 h = 60 min = 3,600 s.

1 Julian year

365.25 d = 31,557,600 s.

1 shake

1 shake = 10 ns = 10⁻⁸ s.

Common Mistakes

Treating all months as 30 days. Using "year" without specifying common, Julian, or tropical. Confusing duration conversion with timezone conversion.

Limitations

Astronomical values are approximate. Not for legal timekeeping or navigation-grade ephemeris.

FAQ

What does a Time Converter do?›

It converts time durations between units using seconds as the internal reference.

What is the SI unit of time?›

The second (s).

How many seconds are in an hour?›

1 hour = 3,600 seconds.

How many seconds are in a day?›

1 day = 86,400 seconds (exactly 24 hours).

Why is a month not always exact?›

Civil calendar months vary from 28 to 31 days. This tool uses labeled definitions like synodic month or average Gregorian month.

What is a Julian year?›

365.25 days = 31,557,600 seconds exactly.

What is Planck time?›

A theoretical physics time scale ≈ 5.39×10⁻⁴⁴ s (CODATA approximate).

How do I convert milliseconds to seconds?›

Divide milliseconds by 1,000. Example: 500 ms = 0.5 s.

Is this a timezone converter?›

No. It converts durations only, not clock times or UTC offsets.

Sources

  1. BIPM: SI Brochure
  2. NIST SP 811
Manish Kumar

Author & technical reviewer

Manish Kumar

PhysicsCalcs tools are reviewed with an educational focus: clear formulas, transparent assumptions, and practical context for students and science learners.

Learn more about Manish