How I read Unix timestamps without guessing seconds or milliseconds

A timestamp bug often starts with one question: is this value in seconds or milliseconds? Getting that wrong can move dates to 1970 or far into the future.

The Timestamp Converter tool is useful because it lets me check the result in a small, controlled place before I use it in a bigger workflow.

The simple idea

A timestamp bug often starts with one question: is this value in seconds or milliseconds? Getting that wrong can move dates to 1970 or far into the future.

The goal is not to click buttons quickly. The goal is to understand the input, produce the expected output, and notice anything that could be misleading.

Step 1: Paste the timestamp

Paste the timestamp.

Start with a small example if possible. Small examples make mistakes easier to see.

Step 2: Check whether it looks like seconds or milliseconds

Check whether it looks like seconds or milliseconds.

Step 3: Convert to UTC and local time

Convert to UTC and local time.

Step 4: Compare with the event you expected

Compare with the event you expected.

Step 5: Convert ISO strings back to Unix time when needed

Convert ISO strings back to Unix time when needed.

Be explicit about time zone when sharing results.

Step 7: Store timestamps consistently in systems, usually UTC

Store timestamps consistently in systems, usually UTC.

My checklist

Before I trust the result, I check:

Paste the timestamp.
Check whether it looks like seconds or milliseconds.
Convert to UTC and local time.
Compare with the event you expected.
Convert ISO strings back to Unix time when needed.
Be explicit about time zone when sharing results.
Store timestamps consistently in systems, usually UTC.

The tool handles the mechanical part. I still review the result before I publish it, send it, or use it in production.