"How to determine measurements for a project"

Should you wish to 'get creative' with your squares and need a particular size, this is how you would work out the size and quantity of squares you would need.

Let's assume you want to make a pram blanket with a finished measurement of 60cms x 45cms (or 24ins x 18ins).  This could divide into twelve 15cms (or 6ins) squares which would then equate to four rows of three squares in each row.  A total of 12 squares in all to complete the blanket.
To determine how many stitches you would need to work to for each square before starting to decrease, increase as described earlier until the measurement up one side of the 'V' shape you are creating (ie tip of work to needle) measures 15cms (or 6ins).  When you have reached the 15cms (or 6ins) measurement, count the number of stitches on the needle and make a note of that number, before starting to decrease.  You would then knit the remaining 11 squares to that same number of stitches to complete the 12 squares needed for the finished blanket.

This same technique can be used to 're-size' any number of projects.