Timestamp Converter

Unix timestamps are simple numbers that represent seconds since 1970-01-01 UTC. They are reliable for storing and comparing events, but people think in local time, not in epoch seconds. This converter bridges that gap. You can convert epoch to a readable date-time in a selected time zone and format, or parse a human date-time and return epoch seconds and milliseconds. It is a small tool, but it eliminates a surprising amount of friction in debugging, data review, and scheduling across regions.

Quick start - two directions, one habit

Paste an epoch into Epoch → Human and pick a time zone. If your number is in seconds, the tool multiplies by 1000 to create a JavaScript Date. Choose a format - ISO 8601 for APIs, RFC 2822 for headers, or a simple numeric YYYY-MM-DD HH:mm:ss for spreadsheets and quick notes. For the reverse flow, write a date-time in that numeric format and choose the time zone that date-time should be interpreted in. The output gives epoch seconds and milliseconds you can paste into code, SQL, or a log search.

Time zones and offsets - avoid manual math

Converting by hand is error-prone because of daylight saving shifts and historical changes. This tool relies on the platform’s IANA time zone support through Intl.DateTimeFormat, which applies rules correctly for named zones like America/New_York or Asia/Kolkata. If you want a quick background on how time zones are defined, the IANA time zone database is the definitive source used by many systems. The important practical rule - always store UTC in systems and convert to local zones at the edge for display and input.

Formats that travel well

ISO 8601 is unambiguous and widely accepted by APIs and databases. A form like 2025-05-16T00:00:00Z states UTC explicitly. RFC 2822 - Fri, 16 May 2025 00:00:00 GMT - is common in email headers and some logs. The plain numeric format in this tool is good for quick humans-first tasks, but when you paste into systems, prefer ISO so offsets are explicit. If you are sending event times between services, agree on an ISO format and a zone - ideally Z for UTC - to eliminate guesswork.

Parsing input - say what you mean

When you enter a human date-time for conversion to epoch, the tool interprets it in the selected zone you provide. This is important for scheduling and backfills. If you say 2025-05-16 09:00:00 in Europe/London, the epoch will differ from the same clock time in America/New_York. That is expected - the planet is big. The rule is to be explicit: always pair a local time with its zone region when you plan or record an event. Your future self will thank you.

Common cases - debugging, CSVs, and migrations

When reading logs, you often see epoch milliseconds. Paste them and pick a zone to identify what happened around a specific minute for a customer. For CSV exports, convert a column to numeric epochs to simplify joins and comparisons in SQL - date math becomes easier with seconds. During migrations, ensure that source systems and target systems agree on the epoch units - seconds vs milliseconds - and the zone used for display fields. A mismatch here causes off-by-hours bugs that are hard to spot until customers report odd times.

Comparison - manual math vs converter

Bullet notes - timestamps without surprises

• Store UTC in systems and convert to local time only for display or input.
• Be explicit about zone when scheduling - pair clock time with region.
• Confirm epoch unit - seconds or milliseconds - before writing code.
• Prefer ISO 8601 in APIs to avoid ambiguous offsets.

Real example - resolving a “missing” order

A support ticket claimed an order vanished between 1 am and 2 am local time. Logs were in UTC epoch milliseconds. Converting the ranges to the customer’s zone revealed that the order was created at 01:30 during a DST fall-back hour and displayed later with a duplicated hour label. The data was fine - the display was confusing. After we rewrote the UI to show full times with zone abbreviations, complaints stopped. The converter made the investigation ten minutes instead of an afternoon.

Two questions before you publish times

• Are you showing users a time with a clear zone so they do not assume “local” incorrectly?
• Does every conversion in your code handle DST boundaries and the seconds-vs-milliseconds distinction consistently?

Timestamps look simple because they are just numbers, but the meaning depends on zone and format. With a small habit of explicit zones and ISO strings, you avoid nearly all the surprising bugs. If you want a deeper dive into how systems keep time, the NIST time and frequency division hosts readable explainers and links to standards that underpin the clocks we use.