There are many different makes and models of chalk line available and each may vary in the size of their box capacity, string length and their gear ratio. Below is guide to help you decide which is the right one for you.
Standard chalk lines
Box capacity
The box of standard chalk lines can typically hold between 30-60g (1-2oz) of chalk powder. Standard models of chalk line will impart many lines before you need to refill them. They are recommended for moderate to frequent users.
Which should you choose?
This all depends on how frequently you are going to be using your chalk line. The larger capacity for chalk your chalk box has, the less frequently you will have to refill it. Chalk box capacities typically range from 20-60g (3/4-2oz) of chalk powder, though there are heavy-duty models that can hold upto 225g (8oz).
String lines
Strings that are supplied with a chalk line come in lengths of between 15-60m (50-200ft). Choose one that will be suitable for your work project.
Replacement string lines
Replacement string lines can be purchased in lengths of between 15-60m (50-200ft), though longer string line spools are available from which you can cut a required length string. These string line spools can measure up to 300m (985ft) in length.
Gear ratio
Most standard chalk lines have either a 1:1, 2:1, 3:1, 3.5:1, 4:1 or 5:1 gear ratio.
Compact chalk lines
There are compact chalk lines available which are usually less than half the size of a standard chalk line. They are lightweight gadgets that typically have string line of between 9-15m (30-50ft) in length, and a box that can hold between 20-30g (3/4-1oz) of chalk powder. Various geared crank ratios are also available.
These chalk lines are ideal for the occasional user or for your smaller home DIY projects like marking lines prior to hanging wallpaper, but for your bigger jobs you may want to consider buying one with a longer line.