C# Unix Timestamp Guide
C# and .NET provide the DateTimeOffset class which has built-in methods for Unix timestamp conversion. The ToUnixTimeSeconds() and FromUnixTimeSeconds() methods make conversion straightforward. For high precision, use ToUnixTimeMilliseconds().
Unix timestamps are a universal way to represent a specific moment in time as a single integer, counting the seconds elapsed since January 1, 1970 (the Unix epoch). Working with timestamps in C# is a common task for developers building applications that log events, schedule jobs, compare dates, or communicate with APIs. The examples below cover the three most essential operations: retrieving the current timestamp, converting a timestamp into a human-readable date, and converting a date back into a timestamp.
Get Current Timestamp
The most common starting point is to capture the current moment as a Unix timestamp. In C#, you can obtain the number of seconds (or milliseconds) since the epoch using built-in functions. This value is useful for recording when an event occurred, setting cache expiry times, or generating time-based identifiers.
Get Current Unix Timestamp
using System;
// Get current Unix timestamp
long timestamp = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
Console.WriteLine(timestamp); // e.g., 1706745600
// With milliseconds
long timestampMs = DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();Convert Timestamp to Date
Once you have a Unix timestamp, you often need to display it in a human-readable format. Converting a raw integer like 1706745600 into a formatted date string such as "2024-02-01 00:00:00" makes it meaningful to end users. The following C# code demonstrates how to perform this conversion with proper timezone handling.
Convert to Date
using System;
// Convert Unix timestamp to DateTime
long timestamp = 1706745600;
DateTime dt = DateTimeOffset
.FromUnixTimeSeconds(timestamp)
.DateTime;
Console.WriteLine(dt);
// 2/1/2024 12:00:00 AMConvert Date to Timestamp
The reverse operation is equally important. When users provide a date through a form or when your application reads dates from a file, you need to convert them into Unix timestamps for storage, comparison, or transmission via APIs. Here is how to convert a date or date string into a Unix timestamp in C#.
Convert to Timestamp
using System;
// Convert DateTime to Unix timestamp
DateTime dt = new DateTime(2024, 2, 1, 0, 0, 0, DateTimeKind.Utc);
long timestamp = new DateTimeOffset(dt).ToUnixTimeSeconds();
Console.WriteLine(timestamp); // 1706745600Common Pitfalls in C#
Working with timestamps can be error-prone, especially across different platforms and timezone configurations. Being aware of these common mistakes will help you write more robust C# code and avoid subtle bugs that are difficult to trace in production.
- 1DateTime.Kind must be set to Utc when converting to Unix timestamps to avoid timezone issues
- 2DateTimeOffset.FromUnixTimeSeconds() returns UTC — convert to local time explicitly if needed
- 3DateTime and DateTimeOffset are different types — prefer DateTimeOffset for timestamp work
- 4The .NET epoch methods were added in .NET 4.6 — older versions need manual calculation
Best Practices for Timestamp Handling
Regardless of the programming language, following a few best practices will keep your timestamp code reliable. Always store and transmit timestamps in UTC to avoid timezone ambiguity. Use seconds-based Unix timestamps unless your application requires sub-second precision, in which case milliseconds or microseconds are appropriate. When displaying dates to users, convert from UTC to their local timezone only at the presentation layer. Document whether your APIs expect seconds or milliseconds, as mixing the two is one of the most frequent sources of timestamp bugs.
Frequently Asked Questions
Related Tools
Timestamp Guides for Other Languages
Need Unix timestamp examples for a different programming language? Browse our complete collection of language-specific guides with copy-paste code snippets.