How to measure request timing with cURL

Evaluating request latency helps identify performance bottlenecks, validate infrastructure changes, and ensure user experience meets expectations. Timing metrics reveal where delays occur during connection and data transfer.

cURL provides timing variables like %{time_connect}, %{time_starttransfer}, and %{time_total} via --write-out. Examining these values assists in optimizing server responses, comparing endpoints, or benchmarking configurations.

With actionable timing data, administrators and developers can refine caching strategies, scale resources, or update network policies to reduce load times and enhance overall performance.

1. Open a terminal.
2. Use --write-out to print timing after the request completes.

   $ curl "https://www.example.com" --write-out "Time_Total: %{time_total}\n"

   Print total time to gauge response performance.

3. Include multiple variables for detailed insight.

   $ curl "https://www.example.com" --write-out "Connect: %{time_connect} TTFB: %{time_starttransfer} Total: %{time_total}\n"

   TTFB (Time To First Byte) indicates how quickly the server responds.

4. Use –silent and –output /dev/null to measure times without clutter.

   $ curl --silent "https://www.example.com" --write-out "%{time_total}\n" --output /dev/null

   Focus only on timing data for clear comparisons.

5. Compare timings across different servers or endpoints to identify performance differences.

   Consistent measurement informs ongoing optimization efforts.