Convert Between Time Units Instantly Convert between milliseconds, seconds, minutes, hours, days, weeks, months, and years.

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Time Converter

Convert between milliseconds, seconds, minutes, hours, days, weeks, months, and years.

Enter time

Type the time duration to convert.

Select units

Choose source and target time units.

View the converted time

Converted time appears instantly.

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What Is Time Converter?

A time converter translates between units of duration. The second is the SI base unit of time, defined by the cesium-133 atomic transition frequency. Minutes, hours, days, and weeks have exact relationships to the second. Months and years are averaged values: the converter uses a mean Gregorian year of 365.2425 days, and a mean month of 30.436875 days (one-twelfth of a year). This handles the practical need to convert durations while acknowledging that actual months vary from 28 to 31 days and years alternate between 365 and 366 days.

Why Use Time Converter?

Covers eight time units from milliseconds to years.
Uses precise mean values for months and years.
Essential for project planning and duration calculations.
Real-time bidirectional conversion.
Completely client-side.

Common Use Cases

Project Management

Convert project durations between weeks, months, and days.

Programming

Translate between milliseconds, seconds, and other units for timeout and animation values.

Science

Express experimental durations and decay times across different time scales.

Everyday Planning

Calculate how many hours are in a week or how many days until a deadline.

Technical Guide

Since 1967, one second equals exactly 9,192,631,770 periods of the cesium-133 atom's ground-state hyperfine transition.

Exact relationships:
• 1 minute = 60 seconds
• 1 hour = 3,600 seconds
• 1 day = 86,400 seconds
• 1 week = 604,800 seconds

Averaged relationships (Gregorian calendar):
• 1 year = 365.2425 days = 31,556,952 seconds
• 1 month = 365.2425/12 days ≈ 30.44 days = 2,629,746 seconds

The millisecond (0.001 s) is crucial in computing for measuring response times, animation frames (16.67 ms at 60 fps), and network latency. The microsecond (10⁻⁶ s) and nanosecond (10⁻⁹ s) are used in high-performance computing and electronics.

Tips & Best Practices

1
Quick math: 1 year ≈ 365.25 days ≈ 8,766 hours ≈ 525,960 minutes ≈ 31.56 million seconds.
2
For programming: 60 fps = one frame every 16.67 milliseconds.
3
There are exactly 168 hours in a week (7 × 24).
4
A month averages about 30.44 days or 4.35 weeks.

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Frequently Asked Questions

Q How many seconds are in a day?

Exactly 86,400 seconds (24 × 60 × 60).

Q How many hours are in a year?

Approximately 8,766 hours (365.25 × 24).

Q Why does the converter use 365.2425 days per year?

This is the mean Gregorian calendar year, accounting for leap years. It's more accurate than 365 or 365.25.

Q How many weeks are in a month?

On average, about 4.35 weeks (30.44 days ÷ 7).

Q How many milliseconds in a second?

Exactly 1,000 milliseconds.

About This Tool

Time Converter is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.