To every sewist or fashion design student eager to create a well fitted pants pattern our math free approach makes it simple. Learn to draft your custom basic pants pattern with confidence and ease leaving frustration behind. Use our free interactive pants block tutorial to build your basic block from scratch effortlessly.
How the interactive tutorial works in 3 easy steps
1. Fill in your measurements
Easily input your body measurements, as shown in the illustrations and get a custom no-math pattern drafting tutorial.
2. Get a personalised tutorial
Click “Design tutorial” to receive a personalised pattern drafting guide with computed values for each step.
3. Download instantly without waiting
Download your customised PDF tutorial instantly onto your phone or computer.
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
What is a basic pants block?
The basic pants block (or basic pants sloper) is one of the essential foundation patterns in fashion design, right alongside the bodice, skirt, and sleeve blocks. Drafting your own custom-fit pants block gives you the perfect starting point for creating pants, shorts, culottes, and more — all tailored precisely to your body shape.
With this block as your base, you can easily experiment by adjusting the waistline, lengthening or shortening legs, shaping the seat, adding darts, pleats, or style lines to create countless designs that fit beautifully and look professional.
For a deeper dive into the anatomy and function of each pants part, check out this post on pants parts.
This page contains the following:
- How to take body measurements
- Interactive basic pants pattern tutorial
- Tools you will use to draft the basic pants pattern
- How to draft a basic pants pattern step by step
- Working with the basic pants sloper
- Basic pants pattern FAQs
How to take body measurements
- Use a flexible tape measure: Ensure it is not stretched out and is flexible enough to contour to the body’s curves.
- Wear fitted clothing: When taking measurements, wear fitted clothes or underwear to get accurate results.
- Stand naturally: Maintain a natural posture without sucking in or pushing out any body parts.
- Get help if needed: Some measurements, such as waist-to-knee, waist-to-ankle, or crotch depth, might be easier to take with assistance.
- Double-check: Measure twice to ensure accuracy.
Basic pants pattern – Interactive tutorial
In the tutorial below, crotch and thigh ease are calculated dynamically from your hip ease to ensure balanced fit and prevent ease clashes that restrict movement. Adjust hip and waist ease freely, the tutorial adapts automatically for comfort and shape.
Need more time to gather your measurements? Download this pants measurements cheat sheet: a one-page, print-ready PDF with clear illustrations. Fill it out at your own pace, then return to enter your measurements into the interactive tutorial below.
Natural waist circumference
Hip circumference
Waist to hip length
Thigh circumference
Waist to knee length
Waist to ankle length
Crotch depth (ease)
Seam and hem allowance
We do not store, nor share any data you put into the form above.
How to draft the basic pants pattern step-by-step
Prepare the following tools for drawing the basic pants pattern:
- pencil
- eraser (for correcting mistakes)
- sharpie
- large paper or tissue paper
- long ruler
- French curve ruler (recommended)
In the instructions provided, you’ll notice that certain lines are grey while others are black. I suggest using a pencil to draw the grey lines, as they primarily serve as guidelines to position specific points and parts of the pattern. For the black lines, which represent the actual pattern pieces, use a sharpie to ensure clarity and accuracy.
If necessary, iron the tissue paper before drawing the pattern. Never use creased or crumpled paper for drawing patterns.
Drafting the FRONT and BACK pattern pieces
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
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
Mark the crotch depth, including ease for comfort.
c = crotch depth + ease at crotch
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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)
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crotch depth =
ease at hip =
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
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).
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”)
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hip circumference =
ease at hip =
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”)
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hip circumference =
ease at hip =
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”)
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”)
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waist circumference =
ease = 1 – 3 cm (3/8 – 1 1/8”)
1 cm (3/8”) = dart width / 2
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”)
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
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hip circumference =
back shift = 3 cm (1 1/8”)
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.
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
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waist length BACK =
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”)
Draw the dart legs from the base markings to the dart point.
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.
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
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
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ease at thigh = ease at hip × 0.8
0.9 = slims thigh fit
0.47 = overall FRONT leg share
2 = halves the leg width
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thigh circumference =
ease at hip =
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
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ease at thigh = ease at hip × 0.8
0.9 = slims thigh fit
0.53 = overall BACK leg share
2 = halves the leg width
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thigh circumference =
ease at hip =
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
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hip to knee length =
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.
Now, transfer the finished pattern onto your fabric and sew a muslin to test it.
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
- 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.