Instructions: Pants Block

Important Note;  I PLAN re-writing the pants block instructions using another method.  If you have a fairly standard figure the current instructions may work well for you; if you have a non-standard figure they will probably require a lot of fitting at the toile stage.  My new instructions will work better for all figure types; they probably will not be finished until about July 2019.

This page contains the step-by-step instructions for drafting your own Pants Blocks. See the Preliminary pages for:

  • an example of the (standard) block that will be created
  • an example of a personalised block (mine)
  • the measurements used in this example

Scroll down to the bottom of the page for the downloadable PDF file of these step-by-step instructions.

Pants Block Figure 1

Draw a rectangle:

  1. Height of rectangle: From A up to B = Waist to ankle.
  2. Width of rectangle: From B across to C = (Hip ÷2) + 1 inch ease.
  3. Complete the rectangle - making sure all angles are squared.
  4. Label the points A, B, C & D as shown.

instructions-pants-01

Example measurements, Figure 1: Waist to ankle = 39 inches, Hip = 38 inches

Pants Block Figure 2

  1. (Front Hip Arc  ÷ 2) + .31 inch ease: Measure from B on the B~C line.  Label the end point E.
  2. Draw a line down from E, at right angles to the B~C line, the height of the rectangle.  Label the point where it touches the ankle line F.
  3. Waist to knee:  Measure down on the E~F line, and mark the knee depth G.
  4. At point G draw a line the width of the rectangle, at right angles to the E~G line.  Label the end points of this knee line H (back) & I (front) as shown.

instructions-pants-02

Example measurements, Figure 2: Front Hip Arc = 9.25 + .31 inch ease = 9.56 inches.  Waist to knee = 23.5 inches.

Pants Block Figure 3

  1. Crotch Depth: Measure down on the E~F line, and mark the Crotch Depth Point J.
  2. Crotch Depth Line: Draw a line at J, at right angles to the E~F line, across the width of the rectangle.  This is the Crotch Depth line; mark the end points K (back) and L (front).
  3. Hip Depth: Measure down on the E~F line, and mark the Hip Depth Point M.
  4. Hip Depth Line: Draw a line at M, at right angles to the E~F line, across the width of the rectangle.  This is the Hip Depth line; mark the end points N (back and O (front).

Note for the following steps that the (Front Hip Arc + Ease) = L to J, and the (Back Hip Arc + Ease) = J to K.  Measure and note these measurements, which will be needed for some of the following steps.

instructions-pants-03

Example measurements, Figure 3: Crotch Depth = 11 inches, Hip Depth = 8.44 inches.

Pants Block Figure 4

In the following images, the final shape is shown to help clarify what we are doing.

Calculate the Crotch Extensions as follows:

  1. Back Crotch Extension:  (Back Hip Arc + Ease) ÷ 2 - (minus) 0.38 inch
  2. Front Crotch Extension  (Front Hip Arc + Ease) ÷ 4 + (plus) 0.19 inch

Mark the crotch extensions on the block:

  1. Back Crotch Extension: Draw a line, extending the J~K line beyond K.  Label the end point P.
  2. Front Crotch Extension: Draw a line, extending the J~L line beyond L. Label the end point Q.

Mark the Curve Guide Points:

Here we will mark a point that will help us (at a later stage) draw the front and back curves of the crotch.  We need to measure a line of a certain length to mark the curve point; the length of this line increases with size.  See the Preliminary page for the length of the line for your hip measurement. 

  1. Back Curve point: Measure out from K on a 45-degree angle to the K~P line.  Mark the end point R.
  2. Front Curve point: Measure out from L on a 45-degree angle to the L~Q line.  Mark the end point S.

instructions-pants-04

Example measurements, Figure 4:

K~J = 10.44 inches, therefore Back Crotch Extension = (10.44÷ 2) - 0.38 =  4.84 inches. 

J~L = 9.56 inches, therefore Front Extension = (9.56 ÷ 4) - .019 = 2.58 inches.

Length of line to place curve points R & S: Back = 1.67 inches, Front = 1.18 inches.

Pants Block Figure 5

Calculate the measurement needed for the placement of the crease line:

  1. Back: (Back Hip Arc + Ease) ÷ 3 - (minus) 0.56 inch
  2. Front: (Front Hip Arc + Ease) ÷ 3 + (plus) 0.56 inch

Mark the crease lines on the block:

  1. Back crease line:  Measure from K towards J on the crotch depth line.  Label the end point T.  At point T, draw a line at right angles to the K~J line, up to almost the waist and down to the hemline. Where this line crosses the knee line, mark it point U, and where it touches the hemline mark it V.
  2. Front crease line: Measure from L towards J on the crotch depth line.  Label the end point W.  At point W, draw a line at right angles to the L~J line, up to almost the waist and down to the hemline.  At the point it crosses the knee line, mark with an X, and where it touches the hemline mark with a Y.

instructions-pants-05

Example measurements, Figure 5

Back Hip Arc + Ease = 10.44 inches, so crease line calculation = (10.44 ÷ 3) - 0.56 = 2.92 inches

Front Hip Arc + Ease = 9.56 inches, so crease line calculation = (9.56 ÷ 3) - 0.56 = 3.74 inches.

Pants Block Figure 6

For this step, you need to refer to the Preliminary Page that gives you measurements to use for the Front Hem Width, Back Hem Width, Front Knee Width & Back Knee Width.  These measurements increase with size and are based on the Total Hem Circumference.

Mark the hem widths on the ankle line, with the crease line as the centre:

    1. Back hem width: Draw the back hemline width, with point V at the centre.  Mark the end points A2 (inside leg) and B2 (side seam) as shown.
    2. Front hem width: Draw the front hemline width, with point Y at the centre.  Mark the end points C2 (side seam) and D2 (inside leg) as shown.

Mark the knee widths on the knee line, with the crease line as the centre.

    1. Back knee width: Draw a line, with point U at the centre.  Mark the end points E2 (inside leg) and F2 (side seam) as shown.
    2. Front knee width: Draw a line, with point X at the centre.  Mark the end points G2 (side seam) and H2 (inside leg) as shown.

instructions-pants-05

Example measurements, Figure 6

Hem width for size 14 = 17.75 inches.  Front = (17.76 ÷ 2) - 0.75 = 8.13 inches,  Back = (17.75 ÷ 2) + 0.75 = 9.63 inches

Pants Block Figure 7

  1. On the pants back, draw a 0.75-inch line from C along the C~E line, then measure up 0.75 inches at right angles to that line, and mark the end point I2.
  2. Measure from I2 to E. Record this measurement for steps in Image 08.
  3. On the front, measure 0.5-inch from B along the B~E line.  Mark this point J2.
  4. Measure from J2 to E, and record this measurement for steps in Image 08.

instructions-pants-06

Example measurements, Figure 6:  Back - I2 to E = 9.68 inches, Front - J2 to E = 9 inches.

Pants Block Figure 8

Calculate:

  1. Back Waist Arc + 0.25 inch ease + 1.5 inches for dart.  Subtract this amount from the measurement I2~E noted in the previous steps.  This is a superfluous amount that needs to be removed from the back side seam.
  2. Front Waist Arc + 0.25 inch ease + 0.88 in for dart.   Subtract this amount from the measurement J2~E noted in the previous steps. This is a superfluous amount that needs to be removed from the front side

Mark:

  1. Back Waist:  Using the measurement calculated above, measure from E, towards C.  At this point measure up .025 inch,  at right angles to the E~C line, and label point K2.  Draw a line from I2 to K2.  This is the back waistline.
  2. Front Waist:  Using the measurement calculated above, measure from E, towards B.  At this point measure up 0.25 inch, at right angles to the E~B line, and label point L2. Draw a line from J2 to L2.  This is the front waistline.

The waistlines will need to be curved a little; that will be done after the darts are created.

instructions-pants-07

Example measurements, Figure 7:

Back Waist Arc = 7.0 + 0.25 ease + 1.5 dart = 8.75 inches.  Measurement from I2~E = 9.68 inches.    9.68 - 8.75 = 0.93 inch from E to K2.

Front Waist Arc = 7.0 + 0.25 ease + 0.88 dart = 8.13 inches.  Measurement from J2~E = 9.06 inches.  9.06 - 8.13 = .93 inch from E to L2.

Pants Block Figure 9

Back Darts

  1. Divide the back waistline I2~K2 by three, and mark the 1/3 and 2/3 points.  These points will be at the centre of the two darts.
  2. Draw the first dart 0.75-inch wide, with the 1/3 point at the centre.  Draw the mid-dart line (shown as a dashed line) down at right angles to the I2~K2 line, making the length of the dart 4.75 inches.  Draw the dart legs from the dart point to the edges of the dart width.
  3. Draw the second dart 0.75-inch wide, with the 2/3 point at the centre.  Draw the mid-dart line (shown as a dashed line) down at right angles to the I2~K2 line, making the length of this dart 4.0 inches.  Draw the dart legs from the dart point to the edges of the dart width.

Front Dart

  1. Measure a dart 0.88-inch wide, with the dart centred on the front crease line.
  2. Draw the mid-dart line down on the crease line, making it 4-inches long. Draw the dart legs from the dart point to the edges of the dart width.

instructions-pants-08

Pants Block Figure 10a

We will now start to draw the outline of the blocks.

  1. Back Crotch to Waist: Draw a curve from P through the curve guide point R to the waist point I2.  You will not be able to draw this curve in one line with a French Curve.  You will need to draw two lines and blend them together.
  2. Back Waist: Draw the waist line from I2 to K2.  This should not be a straight line; see the example in Curving the Waist for Pants.
  3. Back side seam, waist to hip: Draw a straight line (shown in blue in the image) from K2 to M.  At about 3 inches up from the hip, measure out 1/8-inch at right angles to the guideline, and mark a point. (In the image it is shown as a line so it can be more easily seen) This is to assist in making the side seam curve.
  4. Front side seam, waist to hip: Draw a straight line (shown in blue) from L2 to M. At about 3 inches up from the hip, measure out 1/8-inch at right angles to the guideline, and mark a point. This is to assist in making the side seam curve.

instructions-pants-09

Pants Block Figure 10b

Continue outlining the blocks:

  1. Back side seam curve: draw the curve from waist (K2) to hip (M), using the point made in the previous step to create the shape of the curve. The curve should extend out from the straight (blue) guideline, and touch the point 1/8-inch out from that line.
  2. Front side seam curve: draw the curve from waist (L2) to hip (M), using the point made in the previous step to create the shape of the curve The curve should extend out from the straight (blue) guideline, and touch the point 1/8-inch out from that line.
  3. Front crotch to waist: Draw a curve from J2 and through the curve guide point S to Q.  You will not be able to draw this curve in one line with a French Curve.  You will need to draw a few lines and blend them together.

instructions-pants-09

Pants Block Figure 11

We will now draw the inner leg lines; front and back.

  1. Back inner leg: Draw a guide line from P to E2, and mark the half-way point.  Measure inwards at right angles for 0.50-inch.  Draw a curve from P to E2, passing through this point, and blend down to the point A2 on the ankle line.  The line from E2 to A2 should be straight.
  2. Front inner leg: Draw a guide line from Q to H2, and mark the half-way point.  Measure inwards at right angles for 0.25-inch.  Draw a curve from Q to H2, passing through this point, and blend down to the point D2 on the ankle line. The line from H2 to D2 should be straight.

instructions-pants-10

Example measurements, Figure 10

Pants Block Figure 12

To finish off the outline, we need to draw the side seams for the front and the back, from the hip down to the ankle.

  1. Back side seam: Draw a straight line from the knee point F2 to the ankle point B2.  Draw a curve as shown from hip point M down to the knee point F2, and blend into the line down to the ankle.
  2. Front side seam: Draw a straight line from the knee point G2 to the ankle point C2.  Draw a curve as shown from the hip point M down to the knee point G2, and blend into the line down to the ankle.

instructions-pants-11

Pants Figure Block 13

Your block is now finished.  You can now:

  1. Label the block (e.g. Pants Front, Size, Name, etc..)
  2. Cut out the block shape from the cardboard.
  3. Mark the grainlines and crease lines (you can use the grainline to also mark the crease line)
  4. Notch the dart legs, the hip point and the knee points.
  5. Once cut out, check the side seam lengths and the inner leg lengths by walking the seams.

instructions-pants-12

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