Waistcoats are fairly simple, sleeveless garments. You can make a basic pattern for yourself. Once you have a basic pattern, you can make a plain and simple or elegant waistcoat, or add extra touches (such as buttons, pockets or lapels) to suit your style. If you don't have paper large enough to make a waistcoat pattern, tape several sheets together.
Waistcoat pattern back
Measure the widest part of your chest or waist. The measuring tape should be fairly snug, but comfortable.
Divide this measurement in half. Add 6.2 to 7.5 cm (2 1/2 to 3 inches) to this number, for comfort and for seam allowance.
Measure from the top of your shoulder to just below your waist, or to the place where you want the lower edge of the waistcoat. Add 3.7 cm (1 1/2 inches) to this number for seam allowance.
Cut a rectangle of paper as wide as the result of Step 2 and as tall as the result of Step 3.
Measure from the top of your shoulder to the place under your arm where you would like the top of the armhole. Add 1.5 cm (5/8 inch) to this number for seam allowance.
Fold the rectangle of paper in half vertically. Measure from the top of the paper to the top of the armhole. Mark this distance near the edge of the paper that is opposite the fold.
Draw a curved line from this mark to the top of the paper. This will be the armhole of the back of the waistcoat.
Mark the width you want the shoulder of the waistcoat at the top of the paper starting from the edge opposite the fold. Make a mark on the folded edge about 5 cm (2 inches) below the top of the paper. Draw a curved line between these two marks to make the neckline for the back of the waistcoat.
Cut along both lines and unfold the paper.
Vest pattern front
Make a pattern for the back of the waistcoat, following the directions above. Fold the pattern in half vertically and place it on a piece of paper. Trace the pattern for the back of the waistcoat.
Draw a new curve for the armhole that's slightly farther in than the armhole for the back. This will give your arm more freedom of movement.
Draw a neckline for the front of the waistcoat. You may want the front of the waistcoat to be high, cut at a straight angle, low cut or scooped.
Add 3.7 to 5 cm (1 1/2 to 2 inches) to the front of the waistcoat (the area opposite the armhole), if you want the front pieces of the waistcoat to overlap (essential for button waistcoats).
Cut out the pattern for the front of the waistcoat, making sure to use the new lines rather than the tracing lines. Use this same pattern to make the other side of the waistcoat front.
To see if the patterns fit, pin them together along the sides and shoulders and try them on. Then adjust the patterns as needed. You may want to make a waistcoat from muslin (cheap cotton) to test the patterns again before cutting the real fabric.