In a previous grading blog, I showed the first step in developing grade rules. I usually break my measurement and grading charts into two charts. Here is an example:
I usually stop at the middle chart and work the rest of the math out in my head as I grade. Some of you may want to break your measurements down even further. If a pattern piece is symmetrical, you can grade half of the pattern at a time. The third chart shows the grades for half of the pattern width.
My charts have a column on the left titled POM, or point of measure. Those points of measure should correspond to a drawing like this:
The measurements in the top chart above are based off pattern measurements (which are made up for this example), rather than body measurement charts. The grades are developed from body measurements. To grade successfully, you will need to take a lot of measurements off your base size patterns. For a bodice pattern, you will need armhole circumference, across the shoulder neck circumference, neck width, neck depth, and possibly more. Work between your body measurements, pattern measurements, grade, and ease requirements to develop appropriate grade rules for each point of measure. BTW, if your pattern measurements are finished measurements (minus seam allowances), you can use these charts to measure finished garments while doing quality assessments.
There are standard reference grading charts available from various sources. You can refer to them to develop your grade rules, if you like, and it may save you some time. Standard grading charts are usually available for adult, most often, women's clothing. Children's grading charts are available, but I have found them less useful. There are too many variations in children's body measurements, and every company has their own set. I usually have to develop grading charts that are unique for each company. When a designer asks me to grade a pattern, I have to work off of their measurement charts and basic pattern pieces for the grade to make sense. I will compare their measurement charts with my own to make sure their measurement and grades fall within an acceptable range.
If you do use a standard reference grading chart, you will need to double check your pattern/body measurements across the range. Standard grade charts do not accomodate variations in body type that your company may try to fit.
In the next grading blog, I will begin to explain the actual process of grading.