How To Draft A Basic Pants Pattern Step-by-Step

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To every hobby sewist or beginner eager to create a well fitted pants pattern this math free approach makes it simple. Learn to draft your custom basic pants pattern with ease and confidence leaving frustration behind. Use this free interactive pants block tutorial to build your basic block from scratch effortlessly.

This page contains the following:

What is a basic pants block

The basic pants block (or pants sloper) is a core foundation pattern in fashion design, alongside the bodice, skirt, and sleeve blocks. Drafting a custom-fit pants block gives you a precise base for pants, shorts, culottes, and more. Learn more about the structure in this post on individual pants parts.

Tools and measurements you will need

Tools: large sheet of paper, pencil, pen or Sharpie, long ruler, French/flexible curve.

Measurements: Accurate body measurements are essential for drafting a well-fitting pants. If possible, ask a friend to help with measurements. These might be: waist-to-knee, waist-to-ankle, or crotch depth.

  • Wear fitted clothing
  • Stand naturally (do not suck in or push out)
  • Keep the tape measure snug but not tight
  • Measure twice to ensure accuracy

How the interactive tutorial works in 3 easy steps

1. Fill in your measurements

Enter your measurements following the illustrations in the tutorial.

2. Get personalised results

Click “Design tutorial” to get your personalised drafting guide.

3. Download a PDF instantly

Download your customised PDF tutorial instantly.

How to draft a basic pants pattern – Interactive tutorial

Download this one-page, print-ready PDF with illustrated instructions. Fill it out at your own pace, then return to the interactive tutorial below.

Natural waist circumference

Waist circumference is larger than hip circumference.
Waist circumference must be between 45 and 130 cm.
Ease at waist must be between 0 and 5 cm.
Waist circumference must be between 15 and 52”.
Ease at waist must be between 0 and 2”.
A drawing of a person’s torso in a fitted top and underwear, with a measuring tape around the natural waist, labeled

Hip circumference

Your hip is smaller than your waist.
Hip circumference must be between 60 and 165 cm.
Ease at hips must be between 0 and 5 cm.
Your hip is smaller than your waist.
Hip circumference must be between 23 and 65”.
Ease at hips must be between 0 and 2”.
A drawing of a person’s torso in a fitted top and underwear, with a measuring tape around the widest part of the hips, labeled around the widest part of the hips,

Waist to hip length

Waist to hip length must be between 10 and 35 cm.
Waist to hip length must be between 4 and 14”.
A drawing of a person’s torso in a fitted top and underwear, with a measuring tape from the waist to the hips, labeled waist to hip length, indicating the measurement for drafting a basic pants pattern.

Thigh circumference

Your thigh is larger than your waist.
Thigh circumference must be between 15 and 100 cm.
Your thigh is larger than your waist.
Thigh circumference must be between 6 and 40”.
A drawing of a person’s torso in a fitted bodysuit, with a measuring tape around the upper thigh, labeled thigh circumference, indicating the measurement for drafting a basic pants pattern.

Waist to knee length

Waist to knee length is longer than waist to hip length.
Waist to knee length must be between 35 and 120 cm.
Waist to knee length is smaller than waist to hip length.
Waist to knee length must be between 15 and 50”.
A drawing of a person’s lower torso and legs in underwear, with a measuring tape from the waist to the knee, labeled

Waist to ankle length

Waist to ankle length is smaller than to waist knee length .
Waist to ankle length must be between 40 and 150 cm.
Waist to ankle length is smaller than waist to knee length.
Waist to ankle length must be between 15 and 60”.
A drawing of a person’s lower torso and legs in underwear, with a measuring tape from the waist to the ankle, labeled

Crotch depth (ease)

Crotch depth is smaller than waist to hip length.
Crotch depth must be between 15 and 50 cm.
Crotch depth is smaller than waist to hip length.
Crotch depth must be between 6 and 25”.
A side-view drawing of a person sitting on a chair in a fitted bodysuit, with a measuring tape from the natural waist to the chair seat, labeled

Seam and hem allowance

Maximum seam allowance is 3 cm.
Maximum seam allowance is 1”.

Maximum hem allowance is 5 cm.
Maximum hem allowance is 2”.

What’s included after you complete the interactive tutorial

Online tutorial

FREE

✓ Step-by-step illustrations

✓ Custom-fit drafting dimensions

✓ Formulas for calculated values

PDF tutorial

$2.99

✓ Step-by-step drafting illustrations

✓ Custom-fit drafting dimensions

✓ Formulas for calculated values

✓ Your measurements overview

✓ Approximate fabric consumption

Please check and fix your measurements highlighted in red in order to proceed.
You can download a custom-made pants pattern drafting PDF tutorial after entering your body measurements and clicking ‘Design Tutorial’ on this website’s interactive tutorial. This print-ready PDF will save you time, and you won’t need to jot down any information from the webpage. It includes all measured and computed values, along with step-by-step drafting images.

How to draft the basic pants pattern step-by-step

Draw grey lines in pencil as guidelines, and black lines with a Sharpie as the pattern lines. Iron the tissue paper if needed and avoid using creased or crumpled paper.

Drafting the FRONT and BACK pattern pieces

Draw a vertical line for the basic pants pattern block.
a

On a large sheet of paper, draw a vertical line down the centre. This vertical line will separate the FRONT and BACK pattern pieces and assist in drawing the side seams. Mark the waist-to-ankle measurement. This is the total length of the pants. Position the waist near the top of the vertical line.

a = waist to ankle length

Marking a waist to hip length measurement on a vertical line.
b

Measure down from the waist along the vertical line and mark the waist-to-hip length measurement. Mark the waist-to-hip measurement.

b = waist to hip length

Marking a crotch depth measurement with ease on a vertical line.
c

Mark the crotch depth, including ease for comfort.

c = crotch depth + ease at crotch

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

ease at crotch WOMAN = 0.5 × ease at hip + 3/8” (1 cm)​

ease at crotch MAN = 0.5 × ease at hip + 3/4” (2 cm)​

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

crotch depth =

ease at hip =

Drawing a marking the knee line.
d

Measure down from the waist along the vertical line and mark the waist-to-knee length measurement and mark it.

d = waist to knee length

Drawing horizontal lines for the pants pattern block.

Draw horizontal lines intersecting all the markings you’ve made on the vertical line and label them according to the illustration (e.g., waistline, hip line, crotch line, knee line, ankle/hem line).

Marking the outseams on the waist of the basic pants pattern.
e
e
e

On the BACK waist, hip, and crotch lines, mark the measurement according to the formula below. The + 1 cm (3/8”) in the formula ensures the BACK pattern piece is wider than the FRONT to better reflect the body’s shape.

e = (hip circumference + ease at hip) / 4 + 1 cm (3/8”)

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

hip circumference = 

ease at hip = 

Marking the pants' centre at the FRONT and BACK.
f
f
f

On the FRONT waist, hip, and crotch lines, mark the measurement according to the formula below. The – 1 cm (3/8”) in the formula ensures the FRONT pattern piece is narrower than the BACK to better reflect the body’s shape.

f = (hip cicumference + ease at hip) / 4 – 1 cm (3/8”)

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

hip circumference = 

ease at hip = 

Adjusting the centre front and centre back pants seams.
g
h

Shift the marking at the FRONT and the one at the BACK waistline. The front is shifted less than the back, as the lower torso is shallower at the front than at the back.

g =  1 cm  (3/8”)


h =  3.5 cm  (1 3/8”)

Drawing the waist and parts of the outseams.
i
i

From the shifted markings at the waistline, mark the waist width according to the formula below. The added 1 cm (3/8”) in the formula compensates for the 2 cm (3/4”) dart width that you will add to the waist at the BACK.

i = (waist circumference + ease) / 4 + 1 cm (3/8”)

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

waist circumference = 

ease = 1 – 3 cm  (3/8 – 1 1/8”)

1 cm (3/8”) = dart width / 2

Drawing the pants' crotch at the FRONT and BACK.
j
k

To place the centre FRONT and BACK markings in their proper final positions, lower the FRONT crotch and raise the BACK crotch. This adjustment ensures a better fit, as the front of the body is shallower, while the back needs more room to accommodate the buttocks.

j =  1 cm  (3/8”)


k =  2 cm  (3/4”)

Adjusting the pants' crotch at the FRONT and BACK.
l
m

On the crotch line, you need to add something called a crotch extension. More is added to the BACK and less to the FRONT to accommodate human anatomy. Use the formulas below for the FRONT and BACK extensions.

l = hip circumference / 14

m = hip circumference / 14 + back shift

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

hip circumference = 

back shift = 3 cm (1 1/8”)

Drawing the centre front and back seams of the pants.

Now, all the foundational construction lines of the lower torso are complete. Use a French curve to draw the FRONT and BACK crotch, waist, and waist-to-hip curves.

Locating the centre of the pants leg pattern.
n

Now, locate the position of the dart fold line, placing it 1/3 of the waist measurement from the outseam on the back pattern piece. Use the formula below to calculate this 1/3.

l = waist length BACK/ 3

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

waist length BACK =

Marking the inseam and outseam at knee level.
o
p

Draw the dart base by marking 1 cm (3/8”) to the right and left of the dart base centre. Then, draw the dart fold line, making it 12 cm (5”) long.

o = 2 cm (3/4”)


p = 12 cm (5”)

Marking the side seams at knee level.

Draw the dart legs from the base markings to the dart point.

Marking the side seams at knee level.

As the dart was drawn on a curve, its legs are not equal in length. True the dart legs: Prolong the shorter dart leg (in this case, the left leg) to match the longer dart leg (on the right). Adjust the waistline between the outseam and the trued dart leg.

Marking the side seams at knee level.
q
r
s
s
t
t

Now, locate the FRONT and BACK pant leg centres. Measure the distance between the vertical line and the crotch point on each pant leg. Divide this measurement by two (see the formulas below). Mark the results on the knee and ankle/hem line.

q = crotch width FRONT

r = crotch width BACK

s = crotch width FRONT / 2

t = crotch width BACK / 2

Marking the side seams at knee level.
u
u
v
v

Use the provided formulas to locate the outseam and inseam positions on the knee and ankle lines. The width of the pant leg at the ankle/hem line is slightly narrower than at the knee line (it tapers) to ensure a more tailored look.

u = (thigh circumference + ease at thigh) × 0.9 × 0.47 / 2

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

ease at thigh = ease at hip × 0.8

0.9 = slims thigh fit

0.47 = overall FRONT leg share

2 = halves the leg width

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

thigh circumference =

ease at hip =

Marking the side seams at knee level.
w
w
x
x

Use the formulas below to locate the outseam and inseam positions on the knee and ankle lines. The width of the pant leg at the ankle/hem line is slightly narrower than at the knee line (it tapers) to ensure a more tailored look.

w = (thigh circumference + ease at thigh) × 0.9 × 0.53 / 2

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

ease at thigh = ease at hip × 0.8

0.9 = slims thigh fit

0.53 = overall BACK leg share

2 = halves the leg width

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

thigh circumference =

ease at hip =

Marking the side seams at knee level.
y

Locate the ‘flip point’ for drawing the outseam. This is the approximate point where you will flip the French curve from drawing the outer curve to the inner curve. To locate this point, follow the formula below.

y = (hip to knee length) / 2

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯

hip to knee length =

Marking the side seams at knee level.

Now, draw the rest of the pattern and mark the grainline. Use the French curve to shape the lines from the crotch and hip towards the knee line, ensuring smooth, natural curves that follow the body’s contours. Then, use a straight ruler to draw the lines from the knee line down to the hem/ankle, creating a clean, tapered shape.

Marking the side seams at knee level.

Now, transfer the finished pattern onto your fabric and sew a muslin to test it.

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Additional notes

  • Ensure each measurement and marking is done precisely to maintain balance and fit.
  • Always add ease to provide comfort and movement, especially around key areas such as the crotch and hips.
  • The use of a French curve ruler helps in drawing smooth, natural curves at the waist, thigh, and crotch areas.
  • Reduce the amount of ease for a more fitted look, consider using a stretch fabric for the pants.

Working with the basic pants sloper

If you are looking for more inspiration, Patternmaking for Fashion Design by Helen Joseph Armstrong is an excellent resource, with a dedicated chapter on pants and trousers that explores a variety of patterns and creative variations. Following various tutorials in it, you can turn your simple looking basic patterns into an interesting fashion pieces.

Conclusion: Drafting a basic pants pattern block

Creating a basic pants pattern may seem daunting at first, especially with all the different body measurements involved. However, taking it step by step and carefully following the instructions will help you achieve well-fitted pants in the end.

Now that your basic pants pattern is finished, you can move on to drafting additional basic blocks, such as a skirt pattern and a bodice with or without sleeves. My tutorials will guide you step by step to create perfectly basic blocks tailored to your measurements.

Basic pants block drafting FAQs

This custom-fit pants pattern is designed for beginners. The interactive tutorial guides you through each step, transforming confusion into confidence with clear instructions and precise measurement calculations, helping you create a professional pattern even if you’re completely new to drafting pants.
Select stable woven fabrics like cotton or cotton blends for your basic bodice block. These beginner-friendly fabrics prevent distortion and ensure a precise fit. Avoid stretchy or slippery materials like knits or satin until you’re confident, allowing you to draft with ease and achieve a smooth result.
Fabric needs vary based on your measurements. For most adults, a side-by-side layout (pattern pieces placed horizontally) requires 30-50 inches in width × 35-45 inches in length (80–130 cm width × 90–115 cm length), while a stacked layout (pieces placed vertically) needs 15–25 inches in width × 70–90 inches in height (40–65 cm width × 180–130 cm height). Use the interactive tool for a precise estimate, ensuring a seamless drafting process.
Accurate measurements are essential for a custom-fit pants pattern, and the process is straightforward. You’ll need a tape measure, chair, elastic band, pen, and optionally our pants measurements cheat sheet. Place an elastic around your natural waist (narrowest part of your torso) and:
  • Measure your natural waist circumference – the narrowest part of your waist where you placed the elastic band.
  • Measure your hips circumference around their fullest part.
  • Measure your waist-hip length: from the natural waist vertically to the fullest hip line.
  • Measure your tigh circumference at the fullest part.
  • Measure your waist to knee lengt: from the natural waist to your knee.
  • Measure your waist to ankle length: from the natural waist to your ankle.
  • Measure your crotch depth (body rise) like this: sit on the chair, and measure the distance from the natural waist to the chair seat.
To draft your custom pants pattern, gather a large sheet of paper or tissue paper, a pencil (for guidelines), a Sharpie or pen (for final lines), a long ruler, and a French curve or flexible curve ruler (for curves). These accessible tools, combined with the interactive tutorial, turn your measurements into a professional pattern with ease.
Stretch woven fabrics are suitable for a snug, custom-fit pants. Their slight give allows less ease at the waist and hips, creating a tailored look using the same drafting method. This approach helps you craft a pattern with confidence and a comfortable fit.
This pants pattern is designed for woven fabrics, not knits, due to their distinct stretch and need for zero or negative ease.
The pants tutorial or full-scale pattern is a digital PDF, providing instant access to begin drafting your custom-fit design. Use the free interactive tutorial to download it. This format allows you to start creating at your own pace without delays.
If you decide to purchase the PDF tutorial or full-scale pattern, you’ll receive a payment confirmation email with your receipt. Both the custom pants pattern or tutorial PDF is available for immediate download after purchase, allowing you to start crafting your perfect fit without waiting.
The interactive tutorial simplifies pattern drafting by calculating your all necessary measurements for the basic pattern and provides step-by-step illustrations. Just enter your body measurements, and it guides you through drafting a custom-fit pants pattern—without any calculation mistakes.
The custom-fit pants block is a valuable investment, providing a reusable pattern tailored to your body that saves time and money on future designs. Paired with the interactive tutorial, it helps you overcome drafting challenges, building lasting skills and confidence.

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