You can use this tool for free of charge and this tool is definitely available. If your website is loading slow you'll use this tool to see the dimensions of your website which could be large and it can cause loading the web site very slow. It may result during a high bounce rate.
The size of a mean small website is 12 KB which can load very quickly. If there's considerably media such as: pics and videos on your website then it'll load very slow because the size of the web site is extremely large. Embedded media will increase the dimensions of an internet site .
This tool shows the dimensions of an internet site both in Bytes also as KiloBytes(KB).
If the space is restricted as per your web hosting plan then find a far better web hosting plan which provides the simplest hosting at a lower cost . Also, keep tracking that what proportion space is getting used in assessing each website . The important thing is that limit the dimensions of every page of your website in order that it loads faster and it also lowers the bounce rate of the web site .