How to use the french curve for pattern drafting

The french curve is one of the rulers that are constantly used in pattern making, especially when drawing armholes, necklines and sleeves. It is also an instrument that may be confusing for beginners, because they are not skilled at adapting the curves of the ruler to the drawing on paper. With that in mind, I’ve made some guides that show the right position for the ruler in each case.

How to use the french ruler

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There are several models of french curves, but the pattern making types always have a more curved end (on the left in the picture above), and a straighter one (on the right), as well as a concave side (lower part), and a convex one (upper part). Use the more curved end for smaller curves, like necklines, armholes and sleeves. The straighter end is suitable for side seams and darts.

The front neckline:

How to use the french ruler

How to use the french curve on the front neckline: position the curved end on the reference points. The straighter end is pointed up, and the concave side is directed toward center front.

 The back neckline:

How to use the french ruler

How to use the french curve on the back neckline: position the curved end on the reference points, this time a little more tilted than in the previous example. The straighter end is pointed up, and the concave side is directed toward the center. 

The front armhole:

How to use the french ruler

How to use the french curve on the front armhole: In some cases, the curve fits perfectly on the reference points. The less curved end points up, and the convex side is directed toward the center. When it doesn’t fit, do as in the example below.

The back armhole:

How to use the french ruler

How to use the french curve on the back armhole: In some cases, the curve won’t fit. First, fit the first 2 or 3 points, with the straighter end of the curve pointing up, and the convex side towards center. Then tilt the straighter end counterclockwise (if you’re doing the left side) until the curve fits on the remaining points.

The side seam of a dress:

How to use the french ruler

How to use the french curve on the side seam of a dress: 2 or 3 steps may be necessary.
  1.  The straighter end, convex side, is placed along the bust point, while the middle of the curve is placed along the waist point. The curved end is directed toward the hip line. Draw the line from the bust to halfway between waist and hip.
  2. Tilt the ruler clockwise (if you’re doing the right side) until the straight end is pointing down and it touches the hip point. Shift the ruler until its curve is an extension of the curve you drew before. Trace from the merging point to the hip line.

I believe if you observe these principles, it will be easy to understand how to use the french curve in a lot of different situations. Remember it is not necessary to do everything in one go, but it is important to do as few steps as possible so the curve remains smooth.

Is there any case in which you still have some difficulty drawing the curve? If you’d like to see other examples, feel free to comment and leave your suggestions below.

This article has 4 comments

  1. Dear Renata

    , how can I be able to get this particular french curve

  2. Thank-you for sharing this information, it was so helpful!

  3. Hi Renata,
    I have been trying to find a French Curve like this & have looked online but can’t find one. can you tell me where to actually get one?? 
    thanks,
    Sybil

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