---
title: X-Timer
summary: null
url: https://www.fastly.com/documentation/reference/http/http-headers/X-Timer
---



```
S{unixStartTimeSeconds},VS0,VE{durationMilliseconds}
```

`{unixStartTimeSeconds}` is [a Unix timestamp](https://en.wikipedia.org/wiki/Unix_time) for when the request was first received by Fastly.  It is given in seconds but to microsecond precision.

The value `{durationMilliseconds}` is an integer number of whole milliseconds elapsed since the start time of the request.  In the event of a cache hit, this will most likely be zero, since the time required to look up and serve a cached object is usually under a millisecond. For a cache MISS, the number represents the number of milliseconds it took to retrieve the data from your origin server and send the response back to the requester.

> **HINT:** You can use VCL [functions](https://www.fastly.com/documentation/reference/vcl/functions/date-and-time/) and [variables](https://www.fastly.com/documentation/reference/vcl/variables/date-and-time/) to control dates and times.