The Miss Ruby Tuesday (MRT) pattern covers sizes xxs- 6xl (30-54 inch bust), and the add on pack goes to 3xl (30-46 inch bust). This post will teach you how to grade the pattern up or down two sizes (which is four inches), but you can go beyond that, if you wish.
Let’s get started!
The same method shown here can be used to grade up and down most patterns. All patterns are not created equal, and if your pattern doesn’t have consistent grading between sizes, you won’t be able extend the sizing easily. To check if your pattern is suitable before you buy it, check out the measurement chart. For example, the MRT has exactly 2 inches between each size. Patterns not suitable for grading will have an inconsistent measurements between sizes.
First up, you will need to draw a straight line on the outside shoulder seam. Grab your ruler, find the centre point of the shoulder seams and draw a straight line through it, extending it an inch or two on either side. I’ve done so in green below.
Next, do the exact same thing with the inside shoulder seam. The below picture also shows the third step. You need to measure the distance between each size. In this case the sizes were 8mm apart, so I plotted points on my green lines at 8mm, and then again at 16mm. It’s the same thing, whether you’re going up or down.
Next, grab your ruler again, and draw a line between the first pair of dots at 8mm, and the second pair at 16mm, connecting the outside and inside shoulder seams. I have done 8mm in pink and 16mm in blue below.
Next, we will repeat the previous steps with the top and bottom corners of the side seam.
Next, move onto the armscye. This time you will draw a few lines that run through the armscye.
You can see in the image above I have measured the distance between the sizes and then added that to my blue lines. This is the same as what we did at the shoulder seams.
Next, draw lines that continue with the curve of the armscye, ensuring they match with the measurements we just placed on our lines. If you have a French curve, it will be a great help here to get nice smooth, straight lines. If, like me, you have an overly helpful husband who melted your French curve in the dishwasher, you can just free hand them in.
Next, move onto the neckline, and any other pattern pieces that need grading. I won’t explain any further as this same process is repeated, so I would only be repeating myself. If you have any questions, please let me know.