Units of Time in Computing

Understanding different time units is crucial when working with Unix timestamps, scheduling, and time-based calculations in programming. Whether you're using timestamp conversion tools or developing applications, knowing how time units relate is essential.

Standard Time Units

Time can be measured in various units, each serving different purposes in computing and everyday life:

Basic Units

• Second: The base unit of time in the International System of Units (SI).
• Minute: 60 seconds.
• Hour: 3,600 seconds (60 minutes).
• Day: 86,400 seconds (24 hours).
• Week: 604,800 seconds (7 days).

Sub-second Precision

• Millisecond (ms): 1/1,000 of a second.
• Microsecond (μs): 1/1,000,000 of a second.
• Nanosecond (ns): 1/1,000,000,000 of a second.

Time Units in Programming

Different programming languages and systems use various time units as their standard:

Seconds-based Systems

• Unix timestamps (traditional).
• Python's time.time().
• PHP's time().
• C/C++ time_t.

Milliseconds-based Systems

• JavaScript Date.now().
• Java System.currentTimeMillis().
• .NET DateTime.Ticks (100-nanosecond intervals).

Conversion Between Units

Converting between time units is straightforward with multiplication and division:

Common Conversions

• Seconds to milliseconds: multiply by 1,000.
• Milliseconds to seconds: divide by 1,000.
• Hours to seconds: multiply by 3,600.
• Days to seconds: multiply by 86,400.

Code Examples

// JavaScript: seconds to milliseconds
const milliseconds = seconds * 1000;

# Python: milliseconds to seconds
seconds = milliseconds / 1000

Time Unit Selection Guidelines

Choose the appropriate time unit based on your application's needs:

Use Seconds When:

• Storing timestamps in databases.
• Working with Unix systems.
• Human-readable time intervals (minutes, hours, days).
• Memory or bandwidth is constrained.

Use Milliseconds When:

• High precision timing is needed.
• Working with animations or UI interactions.
• Measuring performance or benchmarking.
• JavaScript-heavy applications.

Use Microseconds/Nanoseconds When:

• Scientific computing.
• High-frequency trading systems.
• Real-time systems.
• Precise performance profiling.

Time Units in Different Contexts

Database Storage

Most databases store timestamps as seconds or milliseconds since epoch. Choose based on your precision requirements and the database's native timestamp format. Always store times in UTC to avoid timezone-related issues. You can use a timestamp generator to create test data.

API Design

For REST APIs, Unix timestamps in seconds or ISO 8601 strings are common. Milliseconds may be used for high-precision applications.

User Interfaces

Display times in human-readable units (minutes, hours, days) while storing precise timestamps internally for calculations.

See time unit examples in programming languages

Convert between different time formats