Sewing 207 - Pattern Drafting: The Basic Trousers (Pants)

Kaine
Feb 12, 2021
4 min read

Updated: Jul 2, 2024

Today we shall draft the Trousers block. From this you can make any style of trousers or shorts and it can even be used for Jumpsuits.

Principles of pattern drafting.

We shall be drafting a whole Front piece and Back piece. Trousers are bifurcated garments as you need two sets of each piece (front and back) for each leg. Depending on the part of the body, some measurements will be divided into 2, and some will be divided into 4. It will all become clearer as we draft.

Tools you will need

1. Straight ruler

2. Set square

3. Curve ruler

4. Pencils / Eraser /Sharpener

5. Brown paper/ Drafting Paper - 1 sheet (50L x 50W inches) or 2 sheets ( 50L x 20W inches) each

Measurements you will need (Feel free to work in Inches or Cm)

1. Waist

2. Hip

3. Hip depth

4. Crotch

5. Crotch depth

6. Outseam (Waist to Floor)

7. Inseam

8. Waist to knee

9. Knee

10. Upper thigh

11. Foot

IMPORTANT. DOWNLOAD THE WORKSHEET HERE FIRST.

FRONT

1. Leaving a space of about 2 inches (5cm) from the top of the paper, Square a line straight down on the right hand side of the paper. Mark Point A at the top of this line.

2. Point A - B = Hip depth

3. Point A - C = Crotch depth

4. Point A - D = Waist to knee

5. Point A - E = Outseam (waist to floor)

6. Square across guidelines to the left side from points A, B, C, D and E.

7. Line A - F = Front Hip measurement

8. Line F-G-H = Square a straight line down from point F stopping on the crotch line (Line C-I)

9. Line H - I = Front crotch extension measurement

10. Line J-K-L-M = Measure Line C-I and mark mid-point. From this point square a straight line up to the waist line and down to the base line. Label as illustrated (Crease Line)

11. F - * =Move inwards 3/8inch (1cm)

12. Line * - N = Front Waist + Dart measurement. Square up 3/8 inch (1cm) from point N. Label as n1

13. Points O-P = Insert front dart at Point J. Split front dart measurement equally on either side of point J. Label as O and P.

14. Line J - Q = 1/2 Hip Depth measurement

15. Connect points O - Q and P - Q to form dart

16. Connect point P - n1 with a curved line to complete waist

17. Connect points * - I and n1 - B with curved lines to complete centre front and side as illustrated.

18. Line R - S = 1/2 Knee measurement at Point L. Split the measurement equally on either side of point L. Label as R and S.

Alternatively, you can use the length of Line CI minus 1inch -2inches (2.5cm to 5cm) as the length of Line RS.

19. Line T - U = Line RS minus 2inches (5cm). Split the measurement equally on either side of point M. Label as T and U.

20. Connect Points I - R and C - S with gently curved lines

21. Connect Points R - T and S - U with straight lines

That completes the front part.

The Back is a modification of the front. Copy the front unto new paper and flip it horizontally so that the centre front is now on the right hand side.

BACK

22. Line H - 1 = 1/2 of Line H-I (front crotch extension)

23. Line 1 - 2 = Back crotch extension measurement

24. Point J - 3 = 1/4 of Line J - F

25. Point 4 = Join points 1 and 3 with a straight line and extend it pass point 3 by 1.5inch (3.7cm) Label as point 4.

26. Extend the waist from the top corner and hip line out to the left as guidelines (dashed lines)

27. Point 4 - 5 = Measure and mark Back waist + dart measurement.

28. Point 4 - 6 = Hip Depth measurement

29. Point 6 - 7 = Back Hip measurement

30. Join points 5 - 7 and 4 - 2 with curved lines to form centre back and side as illustrated.

31. Highlight Line J - M. This will now be the Crease line for the Back.

32. Line 8 - 9 = Extend Line R-S on each side by 1/2inch (1.2cm). This will make the back 1inch (2.5cm) wider than the front.

33. Line 10 - 11 = Extend Line T-U on each side by 1/2inch (1.2 cm). This will make the back 1inch (2.5cm) wider than the front.

34. Connect Points 7 - 8 and 2 - 9 with gently curved lines

35. Connect Points 8 - 10 and 9 - 11 with straight lines

36. Point 12 = Mark midpoint of line 4-5

37. Split dart measurement equally on either side of point 12. Label as 13 and 14.

38. Point 12 -15 = 3/4 Hip Depth measurement. Make this line perpendicular to line 4-5 or parallel to line 4-6.

39. Connect points 13 - 15 and 14 - 15 to form dart.

This completes the Back.

Please watch the video to see the final step on how to true the crotch curves for easy sewing. Do not skip this step. At this point you can cross check that your upper thigh, knee, and foot are at least a little smaller than lines C, D, and E respectively.

Try it out and let me know how it goes.