(3 * 1024 * 1024 * 8) / (32 * 60 * 60) = 218.45 Mb/sec
This kind of math can be an eye opener. You may have expected to get close to the theoretical throughput of your link. In the example above, the data was transferred over a 1 Gb/sec link, but the actual throughput was only 218 Mb/sec (0.213 Gb/sec or 21.3% efficiency). This seemingly poor performance could have many causes, including performance of the source or destination hosts, high latency on the link, performance of the network gear, bad duplex settings, frame sizes, the list goes on and on. You can use a test like this to identify and troubleshoot the problem.
Once you know the actual throughput you're getting, you can then calculate how long it will take you to transfer other big files. This might be handy if you're migrating servers from one data center to another, and you need to know if you can perform a transfer over a weekend. So we've actually got two calculations to perform.
First we perform a test copy and see what kind of throughput we're getting. In the first calculator below, enter the size of the data transferred, and how long it took, and the resulting throughput will be calculated.
Next, using the throughput calculated above, we can calculate the transfer time, that is, how long it will take to transfer another large file. Click here to use the Transfer Time Calculator. Also, check out our IP Subnet Calculator.