Curl calculates the average speed every second. If the transfer is moving too fast, curl will pause briefly to bring the average back down to your specified limit. You might see the speed fluctuate slightly in your terminal's progress bar, but the overall throughput will remain within your defined bounds. Minimum Limits
It is important to understand that curl does not strictly cap every single packet. Instead, it manages the average transfer speed over a period of time. Averaging Over Seconds
If curl is downloading slower than expected even without a limit, or if your limit isn't behaving as intended, consider these factors: Server-Side Throttling
If you are working on a network with others, a full-speed download can cause high latency (lag) for everyone else. Limiting a large ISO download to a reasonable speed keeps the peace. curl --limit-rate 2M mirror.com Simulating Slow Connections