Unix Timestamp Converter

Tool Overview

This tool converts a Unix timestamp into human-readable date and time. You enter a number that is either seconds, milliseconds, microseconds, or nanoseconds since the Unix epoch (January 1, 1970 at midnight UTC). The tool shows that moment in UTC, in your local timezone, in ISO 8601 format, and as a relative phrase (for example 2 hours ago). So you see one timestamp in several useful forms.

Developers and support staff often see Unix timestamps in logs, APIs, or databases. A raw number like 1736352000 or 1736352000000 is hard to read. You need to know the unit (seconds or milliseconds) and what time it is in your zone or UTC. This tool takes the number and detects the unit by how many digits it has. It shows UTC, local time with your timezone name, ISO 8601, and a relative phrase. So you can quickly see what time a timestamp is.

The tool is for anyone who works with Unix timestamps. You do not need to be an expert. You enter a number and read the results. You can let the tool detect the unit or choose it yourself. An optional Get AI Insight button may return a short text about the timestamp; that feature can fail and the main conversion does not depend on it.

Background & Concept Explanation

A Unix timestamp is the number of seconds (or milliseconds, microseconds, or nanoseconds) since January 1, 1970 at midnight UTC. Many systems use seconds (often 10 digits) or milliseconds (13 digits). Some use microseconds or nanoseconds. The same moment can be written in any of these units. If you treat milliseconds as seconds you get a wrong date. This tool detects the unit by the length of the number you type. Up to 10 digits (or 11 with a minus) is seconds. Eleven to 13 is milliseconds. Fourteen to 16 is microseconds. Seventeen or more is nanoseconds. So you do not have to choose the unit; the tool picks for you. You can switch to manual mode and pick the unit with buttons if the tool guessed wrong. A related operation involves converting timestamps as part of a similar workflow.

You enter only a number. The tool does not accept a date string. So you always start from a timestamp and get the date and time. The tool shows UTC (the same moment in the reference timezone), local time (in your browser timezone with the timezone name), the same moment in ISO 8601 format (used in APIs and data), and a relative phrase (for example 2 hours ago or in 3 days). So you get both readable dates and standard formats.

People struggle when they convert by hand. They mix up seconds and milliseconds. They use the wrong unit. This tool detects the unit and lets you override it. You see UTC, local, ISO, and relative. You can copy any value. If the number is invalid or out of range the tool says so and does not show a result. The valid range is year 1 to year 9999.

Key Features

• You enter a Unix timestamp in one field. The field accepts only digits and an optional minus sign at the start. The tool allows up to 20 digits. If you enter more the tool shows an error. The tool strips any other characters. So you type a number only.
• When you open the tool the input is set to the current time in seconds. So you see the current moment right away. A Now button sets the input to the current time in the unit you have selected (seconds, milliseconds, microseconds, or nanoseconds). So you can refresh to now in any unit.
• The tool has two modes: Auto and Manual. In Auto mode the tool detects the unit by digit count: up to 10 digits is seconds, 11 to 13 is milliseconds, 14 to 16 is microseconds, 17 or more is nanoseconds. A short line under the input says what was detected (for example Detected as seconds or Detected as milliseconds). You can click Manual to switch to manual mode. In manual mode you see four buttons (S, MS, US, NS) and you click one to set the unit. You can click Auto to switch back. So you can correct a wrong guess.
• When the input is valid the tool shows four result lines. The first is UTC: the date and time in UTC with the label UTC. The second is Local: the date and time in your browser timezone; the label includes the timezone name (for example Local (America/New_York)). The third is ISO 8601: the full ISO string. The fourth is Relative: a phrase like 2 hours ago or in 5 days. Each line has a copy button. So you see the moment in UTC, local, ISO, and relative and can copy any.
• Below the results an optional Get AI Insight button appears. When you click it the tool sends your timestamp and the local date string to a remote service. The service may return a short text (for example a context or comparison). The text is shown under the heading Contextual Insight. If the request fails you see a message like Unable to generate insight at this time or The AI assistant is temporarily unavailable. The main conversion does not depend on this. So you can try to get extra context when the service is available.
• When you have a result three quick action chips appear: Copy Seconds (copies the raw input), Copy Local (copies the local date string), and Copy ISO (copies the ISO string). So you can copy common values with one click.
• If the input is invalid the tool shows an error. Examples: Please enter a valid timestamp (empty or only minus), Input too long. Maximum 20 digits allowed, or Invalid timestamp format (number out of range or conversion failed). The valid range is year 1 to 9999. So you know when to fix the input.

Common Use Cases

You have a timestamp from a server log (for example 1736352000). You paste it into the field. The tool detects seconds and shows UTC, local time, ISO 8601, and the relative phrase. You read the local time to see when it was. You copy the ISO string for a report or API. For adjacent tasks, converting text case addresses a complementary step.

You have a 13-digit number from an API. You paste it. The tool detects milliseconds and shows the correct date. You check the relative time (for example 3 hours ago) to see how old the event is. You use Copy Seconds to copy the raw timestamp for debugging.

You want to see the current time as a timestamp. The tool starts with the current time in seconds. You read the four result lines. You click Now to refresh to the current moment. You can switch to manual mode and set the unit to milliseconds then click Now to get the current time in milliseconds.

The tool detected your number as milliseconds but it is actually seconds. You click Manual then click the S button. The result updates. You read the correct local time and copy the value you need. When working with related formats, converting currencies can be a useful part of the process.

You want a short explanation of the timestamp. After you get a result you click Get AI Insight. If the service responds you see a text under Contextual Insight. If you see Unable to generate insight the main conversion is still correct.

How to Use This Tool

1. Open the Unix Timestamp Converter in your browser. The input is already set to the current time in seconds and the results are shown.
2. Enter or change the timestamp in the input field. Use only digits and an optional minus at the start. The tool allows up to 20 digits. The tool will detect the unit by length: up to 10 digits is seconds, 11 to 13 is milliseconds, 14 to 16 is microseconds, 17 or more is nanoseconds.
3. Optionally click Now to set the input to the current time in the unit you have selected. Optionally click Manual to choose the unit yourself (S, MS, US, NS) if the tool guessed wrong, then click Auto to switch back to auto-detect.
4. Read the four result lines: UTC, Local (with timezone name), ISO 8601, and Relative. Use the copy button on any line to copy that value. Use the quick action chips (Copy Seconds, Copy Local, Copy ISO) to copy common values.
5. If you see an error fix the input. Keep it to 20 digits or fewer. Use only digits and an optional leading minus. Ensure the timestamp is in the range year 1 to 9999.
6. Optionally click Get AI Insight to request a short text about the timestamp. If it loads the text appears under Contextual Insight. If you see an error message the main conversion is still correct.

Calculations & Logic

The tool reads your input as a number. It allows only digits and an optional leading minus. It trims and strips any other characters. The number of digits (ignoring the minus) decides the unit in auto mode: 1 to 10 is seconds, 11 to 13 is milliseconds, 14 to 16 is microseconds, 17 to 20 is nanoseconds. If the digit count is over 20 the input is invalid. The value is converted to milliseconds: seconds times 1000, milliseconds as-is, microseconds divided by 1000, nanoseconds divided by 1,000,000. That milliseconds value must be between minus about 62 trillion and about 253 trillion (year 1 to 9999). If it is outside that range the tool shows no result and you see Invalid timestamp format.

From the moment in time (as a Date) the tool computes UTC using a fixed format (weekday, day, month, year, hour, minute, second in 24-hour form) plus the label UTC. Local time uses your browser timezone (Intl) with full date and long time style. ISO 8601 is the full ISO string from the Date. The relative phrase is the distance from that date to now with a suffix (for example 2 hours ago). So all outputs refer to the same moment. In some workflows, converting Julian dates is a relevant follow-up operation.

The manual unit override (S, MS, US, NS) only affects how the number is interpreted. When you pick a unit the tool uses that unit to convert the number to milliseconds instead of the auto-detected unit. So you can correct a wrong guess. The Now button uses the current unit to set the input (for example current time in seconds or in milliseconds).

Reference Tables or Scales

The tool accepts only a numeric timestamp. It does not accept a date string. You cannot enter a date and get a timestamp back; you enter a timestamp and get the date and time in UTC, local, ISO, and relative form. Copy copies the value you click (one of the result lines or the raw input via Copy Seconds).

Tips, Limitations & Best Practices

Use the unit buttons when the tool guesses wrong. Many timestamps are 10 digits (seconds) or 13 digits (milliseconds). If you paste a 10-digit number and the date looks wrong (for example in the future) it might be milliseconds; switch to manual and click MS to see. If the date is in the past and looks right leave it as seconds. For related processing needs, converting to lowercase handles a complementary task.

Keep the input to 20 digits or fewer. Numbers with more digits show an error. The timestamp must be in the range year 1 to 9999. Negative timestamps (before 1970) are allowed within that range.

This tool converts only from timestamp to date. It does not accept a date string and give you a timestamp. You must have the number first. For date to timestamp use another tool or the same number in a different unit (for example seconds vs milliseconds) with the unit buttons.

Local time depends on your browser timezone. If you are in a different place the local line will not match. Use UTC for a shared reference. The relative phrase (for example 2 hours ago) is from the moment you are viewing to now.

Get AI Insight is optional and can fail. You may see Unable to generate insight at this time or The AI assistant is temporarily unavailable. The main conversion always works with a valid timestamp in the field.

Copy Seconds copies the raw input (the number you typed). Copy Local and Copy ISO copy the formatted local date and the ISO string. Use the one you need for your document or code.