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Java Speedtester FAQ

bits or Bytes, Kilo or kilo.

Computer and networking terminology often refers to bits and bytes, kilos, megas, gigas, and various abbreviations of Megs, Mbits MB's or more. What are all these about? (The bits in grey are a bit more technical)

Starting at the smallest factor is a bit. One bit is a binary digit which contains a value of either zero or one. (Binary is a number system (base-2) represented by two states. A common example of a binary system is a light switch which can either be on or off. Computers use binary as it is easy to represent in electronics often by using a high or low voltage to differentiate between the two values. It can be used to do all kinds of arithmetic similar to our decimal system (base-10) which goes from zero to nine. Other number systems such as octal (base-8) and hexadecimal (base-16) exist which go from zero to seven, or zero to F (fifteen!) respectively. See here for more information on binary.)

If you take eight bits and group them together, they form a byte. (A byte can be of less or more than eight bits and you may see references to 7-bit bytes to depict this. In these instances, the term 'word' is often used to represent a byte.)

In computer technology, abbreviations are used to refer to bits and bytes. Bits are always represented by a lowercase b. Bytes by an uppercase B.

As computers have advanced, lots of bytes are sent and stored, and thus the kilobyte came about. One kilobyte can mean different things. In the same way as measuring the speed of a car in kilometres per hour, kilo can mean thousands of bytes. That is, one kilobyte is 1000 (10^3) bytes. This is often the value used in telecommunications. However, as computers use a binary numeral system, kilo can have a meaning of 1024 (2^10) bytes in data storage.

To differentiate between these two, a lowercase k is normally used to refer to 1000 and an uppercase K to 1024. (International standards disagree that kilo should mean anything other than 1000 and should only be shorthanded with a lowercase k. Kibi has been introduced as an abbreviation to represent 1024 for the computer industry, however this has not been widely accepted and a kilobyte is still often used in reference to 1024 bytes.)

A megabyte (MB) is a multiple of a kilobyte. In fact, its one kilobyte multiplied by itself, so, a kilobyte squared. Thus it can either be 1,000,000 bytes or 1,048,576 bytes depending on whether your kilobyte is 1000 or 1024 bytes.

A gigabyte (GB) is again a multitude of a kilo bigger, so 1000 x 1000 x 1000 (1,000,000,000) or 1024 x 1024 x 1024 (1,073,741,824) bytes.

Hence we come onto abbreviations:

One bit = 1 b
One byte = 1 B (8 bits)
One kilobit = 1 kb (1,000 bits / 1,024 bits)
One kilobyte = 1 kB (8,000 bits / 8,192 bits)
One megabit = 1 Mb (1,000,000 bits / 1,048,576 bits)
One megabyte = 1 MB (8,000,000 bits / 8,388,608 bits)
One gigabit = 1 Gb (1,000,000,000 bits / 1,073,741,824 bits)
One gigabyte = 1 GB (8,000,000,000 bits / 8,589,934,592 bits)

When transferring data over a network it is often desirable to know how many bits or bytes can be transferred ‘per second’. The standard abbreviation for this is /s or ps. 1Mbit/s or 1Mbps are hence commonly used and are interchangeable.

Bits are often used for measuring the capacity or speed of a network or telecommunications channel. Bytes are often used for measuring how much data can be stored on media. It is therefore frequent to hear other abbreviations such as 512k or 8meg. These need to be taken in context. In relation to telecommunications or networking, these generally mean 512kbit/s or 8Mbit/s. In data storage, 512kBytes or 8MBytes.

To confuse the kilo value some more, if you were to transfer a 2MB file (that’s 2 x 1024 x 1024 bytes (kilo as 1024 due to talking about files stored on a computer)) over a network in one second, it would have a transfer rate of 2.048 Megabytes per second (2.048 x 1000 x 1000 (kilo as 1000 as it is over a network))!

In our speedtester we use kilo to refer to a multiple of 1024 to keep things simple!

Why am I having problems with the speedtester?

The speedtester uses a Java Applet to perform a speed test between your computer and our servers. You must have a Java Runtime Environment installed for this to work. We recommend using the latest version of the Sun JRE available here.

Symptom: Nothing (a white space) appears where the speedtest should be and I use Kaspersky Anti Virus (Banner Ad Blocker).

Add the following URL's to the white list under the Banner Ad Blocker settings within Kaspersky:

Symptom: Nothing / a grey box / GetJava appears where the speedtester should be.

When loading our speedtester page you should see our speedtester as in this example:

If you see a grey box or a blank space appears, this means that the Java class file isn't being loaded correctly. This could be for several reasons. Firstly, ensure that you have a Java Runtime Environment (JRE) installed. This is made by Sun, and they have a checker on their website to verify if you have Sun Java installed. If you do not see an animated 'dancing Duke' image you may need to install or upgrade Java. The latest version can be found here.

If you have installed an up to date Java Runtime Environment, but Java still doesn't work, please check through the following steps from Sun to ensure that the browser is configured to run Java applets:

  1. Enable the JRE through your Web browser
  2. Enable the JRE through the "Java Plug-in Control Panel"
  3. Clearing your Web Browser Cache
If problems persist, some users have found that uninstalling and then reinstalling Java can help fix this.

This problem can also occur if you are using security software on your computer such as Norton Internet Security, Norton Personal Firewall or Zonealarm. These software often block Java content from appearing on webpages which will stop our speedtester from working (amongst various other things on the Internet). There is a guide here from Symantec (who make Norton) which should advise how to fix this. If you use other security software or popup blockers and you think this could be a problem, please consult the manual or their technical support for advice on how to enable Java applets.

Symptom: You receive an error message:
Load: class speedtester1 not found.

This is caused by using the Microsoft Java Virtual Machine rather than the Sun version. Microsoft are removing support for their version and may not release any further security updates. We recommend that all users upgrade to the most recent version of the Sun Java Runtime Environment which you can download here.

Symptom: You receive this error message on clicking start:
** An error has occurred while testing **
Unable to connect, please try again later.

This is normally caused by a firewall blocking your connection to the speedtest server. Please ensure that you allow outbound connections to TCP port 8095, and also return data from that port. The 'Port 80' option allows the tester to connect to port 80 on the speedtest server instead of 8095 which may work in some instances where the default port does not.

Symptom: You see a message saying:
Loading results page...

This text is normally shown in the speedtest applet before you are forwarded to your results page. If you do not get forwarded, this could be a problem with the browser, firewall or popup blocking programs which can disable webpages from redirecting you to another web page. We recommend disabling any popup blockers (most web browser have a built in one) and other Internet security programs such as ZoneAlarm or Norton Internet Security/Personal Firewall, and testing again to see if these are the cause of the problem. If this is the cause, we recommend adjusting the settings to allow popups from these websites:, and

This problem has also been reported by users who have installed IE7 and then uninstalled it, reverting back to IE6. This is caused by a problem with the Security settings induced by changing from IE7 back to IE6. The fix is to reset these settings back to the defaults. To do this, in IE7 go to Tools -> Internet Options -> Security and select the 'Default Level' button. Please note that doing so may adjust any custom security settings you may have implemented and you do so at your own risk.

If you still cannot get the speed tester to work you can also estimate your speed using our Download Test Files.

Symptom: The speedtest doesn't work in Google Chrome

You may see a message indicating "No plug-in available to display this content" which means you need to update/install Sun Java 6 Update 12 or above. More details can be found from Sun. You will also need the Flash plugin installed.

Symptom: Your browser closes when you try and use our speedtest

This can occur if there is a problem with your Java installation. Please download the latest version which should fix this issue.

Symptom: You see erratic speeds when using wireless

Try using a wired connection if possible. Wireless networks can see intermittent problems which are indicated by erratic or poor speeds. These can be caused by interference from nearby wireless networks or other wireless devices. If you can't use a wired connection, try changing the Wireless channel used by your router.