Drafting Men's Pants Pattern

Seam allowance is included . It is 0.25 " (0.60 cm)

Drafting the men's pants front pattern.

On a long piece of paper about 4.00" long and 6.00" wide, draw a line down the middle.
Near the top, select a point and mark point 0 .
From 0 down to 1 is -1.00" .
From 1 up measure up 0.00" to 2 .
3 is midway between 1 and 2 ( 0.00" ).
4 from 3 is 2.00 " (5.20 cm) .
Square out from points 0 , 2 , 4 , and 1 .
5 from 2 is 0.00" .
6 from 2 is 0.00"
7 from 2 is 0.00"
Square up from 6 to locate 8 on line 0
Square out from 7 to locate 9 on line 6
10 from 9 is 0.25 " (0.60 cm)
Draw line 8 - 10 .
11 from 10 is 0.00"
12 from 8 is 0.50"
13 and 14 from 4 is 0.00"
15 and 16 from 1 is 0.00"
17 from 1 is 2.00" (allowance for the cuff (if any) is included in this measurement).
Square out from 17 .
The waist line form 8 is squared by line 8 - 10 until it is about 0.25 " (0.60 cm) below line 8 - 12 . Then it curves gently into 12 .
The fly fall (front rise) follows the straight line 8 - 10 and then makes a shallow curve into 5 .
Through 11 the outseam is vertical from about 1.00 " (2.60 cm) above to 0.50 " (1.30 cm) below. Continue upward, curving into 12 .
Shape the leg, making the inseam and outseam vertical from the bottom to at least 2.00 " (5.20 cm) above 15 and 16 and identical to each other from the bottom to the knee. Above the knee the inseam is a natural continuation, waiting until almost the top to curve into 5 . The outseam also continues naturally above 14 , easing outward to meet the continuation downward from 11 .
Add notches (for assembly) at the following points:

0 , 14 , 16 , 15 , and 13 .
In the outseam, 1.50 " (3.90 cm) below the waist edge, and again 6.25 " (16.25 cm) below that (for the front pockets).
In the fly fall about 1.50 " (3.90 cm) to 2.50 " (6.50 cm) from the inseam: Put the zero end of the tape measure 0.38 " (0.97 cm) below the waist edge and measure along the fly fall 0.25 " (0.60 cm) in from the pattern outline. Cut the fly notch at the nearest whole inch, and that will be the length of your pants zipper.

Drafting the pattern back guide .

The pattern back guide is used to determine the slope of the back pattern piece.
Draw horizontal lines 0 , 7 , and 2 the same distance apart as on the pattern front.
Near the right on line 2 mark point A .
B from A is 2.00"
Square up from A and B to locate C and D on line 0 .
E from B is 1.50"
The distance between E and A should be 0.50"
F from C is 0.25"
G from D is 0.25"
Draw line A - F and locate point X where it crosses the horizontal line 7 .
H from F is 4.50 " (11.70 cm)
From H square down 2.50 " (6.50 cm) to locate J .
K and L are each 0.25 " (0.60 cm) from H .
Draw lines J - K and J - L (back dart).
Draw line B - G and extend it 0.12 " (0.30 cm) to M .
From M square out to 0.12 " (0.30 cm) below the horizontal line 0 ; then curve gradually into K .
From L to F draw a curve that dips 0.12 " (0.30 cm) below the straight line.
Extend the straight lines M - B and F - A to several inches below line A - B , and cut out the pattern back guide along the curved lines M - K and L - F .
Cut out the vee for the back dart, all the way to J .

Drafting the pants back pattern.

For the back pattern, use a piece of paper about 12.00" long and 12.00" wide, draw a line down the middle.
Lay the front pattern piece on the paper, lining up the 0 - 1 line of the front with the line on the paper, and draw around it.
Indicate notches and points 10 and 11 . Take away the front piece and label points 5 , 13 , 14 , 15 , and 16 . Draw line 10 - 11 and extend it to the right.
18 from 11 is 2.00 " (5.20 cm)
Place point X on the pattern back guide on point 18 on the paper. Using the common point as a pivot, swing the guide up until side M - B touches point 10 on the paper.
Draw around the guide above 10 and 18 ( X ). Label M and F .
19 and 20 are 0.50 " (1.30 cm) from 13 and 14 .
21 and 22 are 0.50 " (1.30 cm) from 15 and 16 .
23 from 5 is 0.38" , that is, half of the distance from 7 to 2 plus 0.38 " (1.00 cm) .
23 from 19 is the same as 5 from 13 .
The seat seam (back rise) follows the straight line M - 10 , becomes a shallow curve just outside the 10 - 5 curve of the front, and runs through 5 into 23 , finishing up straight for about the last 1.00 " (2.60 cm) .
From the bottom to the knee the inseam lies 0.50 " (1.30 cm) outside the front outline. Above the knee it continues naturally, doing most of its curving into 23 near the top.
The outseam too is 0.50 " (1.30 cm) outside the front outline from the bottom to just above the knee. Then it eases outward to pass through 18 and curve just outside the F - 18 line into F .
The bottom is in line with that of the front.
Cut out the pattern back, and cut knee and bottom notches.

NOTES:

The seam allowance is 0.25 " (0.60 cm)
The 1.50 " (3.90 cm) that was subtracted when applying the outseam measurement (line 0 - 1 ) represents the finished width of the waistband. It would seem that no seam was allowed for here, but note that line 12 - 11 - 14 - 16 is curved, not straight, and thus is actually greater than the outseam. The seam allowance is included in this curvature.
This also makes the outseam on the front piece slightly shorter than the outseam in the back piece. This is a refinement found in custom-tailored pants. The outseam seam on the pants back is to be eased between about mid-thigh to about mid-calf, making the pants leg curving imperceptibly forward at the bottom.
It was in locating point 18 that both seam allowance and ease are incorporated. Lines 10 - 11 on the front and 10 - 18 on the back together measure half the seat measurement plus 2.00 " (5.20 cm) .
Only very tight pants need provision for dress . The term refers to the side toward which a man places his intimate parts. A man is said to "dress right" or "dress left". Most men dress left.
Dress is allowed for by deflecting the fly seam away from the side toward which the man dresses. The fork of one pants front, usually the right, is reduced by about 0.50 " (1.30 cm)

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[ Updated: 12:08:02 EDT 2012/05/03 ]