Time Converter

title: Time Unit Converter — Convert Seconds, Minutes, Hours, Days, Weeks, Months, Years, and Sub‑second Intervals description: Convert between all common time units using fixed duration factors. Learn how seconds, minutes, hours, days, weeks, months, and years relate, and see how sub‑second units such as milliseconds, microseconds, and nanoseconds fit into the SI framework.

What a time unit converter does

A time unit converter translates a quantity expressed in one unit of time into its equivalent value in another unit. Because time is fundamental to scheduling, scientific measurement, engineering, and everyday life, the ability to move cleanly between seconds, minutes, hours, days, weeks, months, years, and sub‑second fractions is indispensable. The converter applies fixed multiplication factors rather than calendar‑aware logic: every minute contains exactly 60 seconds, every hour contains exactly 60 minutes, and so on. This approach keeps the tool predictable and reproducible regardless of the date, time zone, or daylight‑saving status.

Why fixed factors matter

Calendar‑based conversions introduce variability. A month can be 28, 29, 30, or 31 days; a year can be 365 or 366 days. A fixed‑factor converter deliberately avoids that ambiguity by defining a year as 365 days and a month as 30 days. These definitions are durations, not calendar references. They are widely used in finance, contract drafting, and scientific modelling where a stable, agreed‑upon interval is more important than exact alignment with the Gregorian calendar. When you know the factor never changes, you can compare results across separate calculations without worrying about the start date.

Supported units and their factors

The converter relies on the International System of Units (SI) definition of the second as the base unit of time. Every other unit is derived from the second through a fixed multiplier. The full set of factors used is:

The chain of derivation is straightforward. One day is 24 hours, so 24 × 3,600 = 86,400 seconds. One week is 7 days, giving 7 × 86,400 = 604,800 seconds. A 30‑day month is 30 × 86,400 = 2,592,000 seconds. A 365‑day year is 365 × 86,400 = 31,536,000 seconds. Sub‑second units follow the standard SI prefixes: milli (10⁻³), micro (10⁻⁶), and nano (10⁻⁹).

How the conversion works

Every conversion follows the same two‑step arithmetic. First, the input value is multiplied by the factor of its source unit to obtain an equivalent in seconds. Second, that intermediate value is divided by the factor of the target unit. For example, to convert from hours to minutes, the converter multiplies the hour value by 3,600 to reach seconds, then divides by 60 to land on minutes. The intermediate step cancels out cleanly — hours × 60 directly yields minutes — but the two‑step model generalises to every pair of units in the table, including conversions that cross between macro‑scale and sub‑second units.

Worked example

Consider a conversion of exactly 2 hours into minutes.

The factor for hours is 3,600 seconds per hour, and the factor for minutes is 60 seconds per minute.

Step one: 2 hours × 3,600 = 7,200 seconds. Step two: 7,200 seconds ÷ 60 = 120 minutes.

So 2 hours equals 120 minutes. The same method works identically for any pair of units. If you instead wanted 2 hours in milliseconds, step two would divide 7,200 by 0.001, yielding 7,200,000 milliseconds.

Accuracy and limitations

The fixed‑factor model is mathematically exact for the definitions it uses. Every factor is a rational number, so there is no floating‑point drift when working with integer arithmetic. The main limitation is semantic: a "month" in this converter is always 30 days, and a "year" is always 365 days. Results must not be interpreted as calendar spans. If you need to know how many days separate two specific dates, you need a calendar‑based tool instead. Likewise, the converter does not account for leap seconds, which are occasional one‑second adjustments applied to Coordinated Universal Time (UTC). For most practical purposes — scheduling, billing, scientific notation, and duration estimation — the fixed factors are sufficient and are the standard convention.

Sources

The base unit and the SI prefixes used for sub‑second units are defined in the SI Brochure published by the International Bureau of Weights and Measures (BIPM). https://www.bipm.org/en/publications/si-brochure

The convention for expressing time intervals and the use of non‑SI units such as the minute, hour, and day alongside SI units is described in NIST Special Publication 811. https://www.nist.gov/pml/special-publication-811

Editorial record

This article was drafted to accompany the SoupCalc Time Unit Converter. It describes the fixed‑factor conversion model, lists the complete set of supported units and their multipliers, walks through a worked example, and notes the boundaries of the approach. The text was reviewed for technical accuracy against the SI Brochure and NIST SP 811 and edited for clarity and conciseness. Author: SoupCalc Editorial Team Last reviewed: August 11, 2026.