What Is Network Transfer Speed?

I recently bought a NAS (network attached storage) device from Synology, connected it up to my network and started transferring files. The first thing I noticed was how slow the network transfer speed was. I was copying over some large video files and it was taking forever! I decided to check the transfer speed between my NAS and PC to see the rate the transfer.

I downloaded a program called LAN Speed Test, which had gotten some excellent reviews, and tried it out. Sure enough, my transfer speed was less than 1 MB/s! Note that is megabytes per second, not megabits per second. I’ll go into more detail on Mbps vs MBps and all that fun stuff. After doing some research, I figured out what I was doing wrong and eventually got the transfer rate up to a super speedy 40 MB/s! Technically, you can only get that speed if you’re using gigabit ethernet. I’ll explain more about that below too.

LAN Data Rate Units

First, let’s get the numbers clear. There is standard 100 Mbps ethernet, which is what most people have at home. 100 Mbps is 100 megabits per second. That is translated into 12.5 megabytes per second (MBps or MB/s). It’s much easier to convert to MBs since that is something we are all familiar with rather than bits. This means that if you don’t have a gigabit router and gigabit network card on your computers or NAS, the maximum speed you’ll be able to transfer a file across your home network is 12.5 MBps.

Also, in the real world, it’s impossible to actually get that theoretical maximum. You’ll probably end up somewhere around 4 to 8 MBps. If you are getting something really low like 1 MBps or less, there are reasons for that which I will mention below. Note that even if your computer has a gigabit ethernet card, you won’t get that higher transfer speed unless all the devices that the data is being transmitted through support gigabit.

If you have a gigabit ethernet card on your computer, your router or switch is gigabit and the receiving device also has a gigabit ethernet card, your max transfer speed jumps to a whopping 1000 Mbps or 125 MBps. Again, you won’t get that theoretical speed, but you should be getting anywhere from 30 to 60 MBps depending on the type of files you are transferring and your network setup. Let’s go into more details about that.

Transfer Speed Depends on What?

So as we mentioned above, network transfer speed depends on the type of ethernet you have on your network, but that’s not the only factor. There are several other factors that determine your final transfer speed between two devices.

Hard Drive Speed

One major limiting factor is the hard drive speed. If you have a computer with a 5400 RPM, your transfer rate will be a lot slower than if you have two SSD drives in a RAID 0 configurations! How so? Well, it depends. I’ve heard of some friends getting close to 100 MB/s using some pretty insane setups. On my network, even with gigabit ethernet, I only get around 40 MB/s. One of those reasons is because I have slower hard drives.