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Recreate your favourite trousers pattern

Recreate your favourite trousers pattern

Do you have an ideal pair of trousers that fit perfectly? Then use this tutorial to learn how to recreate your favourite trousers pattern so you can make more. This technique guide is an extract from former Great British Sewing Bee producer Claire-Louise Hardie’s new book Clone Your Clothes (Published by David & Charles) which teaches you how to replicate all your a favourite garments. 

Simple Trousers Tutorial

What you’ll need

Basic tool kit

A pair of well-fitting trousers

Fabric for a toile (muslin)

Fabric for your final cloned version

A zip that’s the same length as the one on your original trousers

Lightweight interfacing

Matching thread


Fabric quantity

These UK size 14 (US size 10) trousers used 1.75m (17/8yd) of fabric 145cm (56in) wide; for larger or smaller sizes (or a different fabric width).


Cloning methods used

Direct Measuring; Tracing

How to make trousers without a pattern

Garment analysis

Analysing your garments is key to making the cloning process a success. Having a list of all the measurements and sewing construction details written out in advance will save a lot of time, both while cloning and when finalizing your patterns.

Make a note of all the pieces you need to make your garment. This is your ‘pattern inventory’, much like the one you usually find inside a commercial sewing pattern. Writing this list means you don’t start making up your cloned garment only to realize you forgot one critical piece.

Apart from naming the pieces (for example, ‘Trouser front), note how many pieces you’ll need to cut from that pattern piece (for example, ‘Cut 2). See below for the pattern inventory for trousers. 

The fabric is a light- to medium weight woven linen, perfect for late spring, summer or early autumn. The original fabric has a crisp quality to it, which holds the shape of the trousers. For the clone I have matched a similar weight of linen fabric.

There is a front zip fly opening, and shaped front patch pockets, back dart, five belt loops set onto a curved waistband. There is also a back welt pocket, which I omitted from my first clone to focus on the fit. The edges of the pocket are turned under once and topstitched and the pocket mouth is faced.

There is a back dart which measures 2cm (3/4in) across the width at the top, making the total dart depth 4cm (11/2in).

The top of the trousers is finished with a contour (curved) waistband which is 4cm (11/2in) deep.

The left and right front waistbands are different lengths. The inner waistband facing has been finished off with a binding.

The hem is a deep 4cm (11/2in) double-folded hem.

Pattern piece inventory

1 x trouser front

1 x trouser back

1 x back waistband

1 x left front waistband

1 x right front waistband

1 x patch pocket

1 x pocket facing

1 x fly facing

1 x fly shield

1 x belt loop (this can be one strip long enough to be cut into five belt loops)

Step 1: Prepare the garment for cloning

Since trousers are a more complex shape to clone, it’s worth taking the time to mark up some balance lines directly onto the garment. These will ensure that you keep the legs on grain. Since chalk and marking pens don’t always rub off, I cloned these trousers inside out.

Chalk over all the seamlines to make them more obvious to see, along with the patch pocket stitching lines and the fly.

Working on just one leg, mark the centre of both the back hem and the front hem.

Measure the halfway point of the inside leg and mark this position at the seam; this is the knee area.

Measure the front and back width of the trousers at the knee line. Mark the halfway point away from the inside leg on both the front and the back.

Keeping the hem very straight, use a long ruler with a squared off end like an L-ruler or quilter’s ruler to draw a line between the mark at the hem and the halfway point of the knee, then extend it all the way to the waist. This long line is the grainline of each side of your trouser.

Line up your ruler with the crotch point, making sure it’s squared off on the grainline. Mark horizontally across the leg. This is your thigh area.

Re-measure each horizontal line and note the hem, knee and thigh measurements. You’ll use them later to compare to your cloned pattern.

Step 2: Clone the front leg

We are using two different approaches to clone the front and back legs of the trousers. This is due to the back of the trousers being larger and sewn into a tube, which makes it very hard to lay them flat and work out the difference.

We will clone the front leg with it laid as a flat whole piece.

Cut your paper at least 20cm (8in) longer than your trouser leg and 15cm (6in) wider than the front piece. For my example this was 110 x 51cm (44 x 20in).

Mark up your balance lines on the paper in the following way. The longer vertical line is the grainline at the centre front and centre back of the leg. The shorter, horizontal line is the hemline.

Line up the hemline of the leg with the shorter balance line, keeping the inside leg seam totally flat. The outside leg seam will have fabric rolling out beyond the seam.

Now align the grainline drawn on your trouser leg with the longer balance line (the grainline) on your paper. Place a pin through this line at the hem, knee, thigh and waistline.

Keeping the hemline aligned with the shorter balance line, anchor all the way along it.

Move up to the knee and anchor in place, working from the centre outwards and making sure that the horizontal line drawn on the trouser doesn’t tilt up or down, which would indicate that the cross grain is wonky.

Then repeat on the thigh line, anchoring it to the paper without making it tilt up or down.

Use a tracing wheel to mark the position of the knee and thigh lines on your paper.

Note: Above the thigh line, you will notice that the back of the trousers has started to curl beyond the seamline at both the inside leg and the outside leg, which is ok! This is the shaping in the back trouser leg allowing for your bottom. So long as you can see your stitch lines, the extracted pattern is good.

Copy your favourite trousers

Working towards the waistline, smooth out from the grainline towards the curve of the hips. It’s important this is fairly taut so that you don’t make your pattern less curved than the original.

Repeat this process from the grainline out towards the fly opening and the crotch seam below the fly.

Anchor the waistline from the side seam across to the centre front fly.

Use a tracing wheel or a large ‘wiggle’ pin to transfer the stitching lines of the whole trouser front onto your paper, including the fly shape and opening. As the fly is a thicker area, use a wiggle pin to trace.

Trace the pocket position before removing the garment, ensuring you have transferred all the stitching lines.

Mark over the holes imprinted in the pattern paper.

How to draft a trousers pattern

Step 3: Check the garment measurements against the traced pattern

You now need to double check the key measurement areas of the pattern against the original garment.

Compare the measurements at the hem, thigh and knee in quarters out from the centre grainline to the side seam, and then from the grainline towards the inside leg. By measuring in quarters, you can apply any corrections in the exact spot it’s needed.

Correct any discrepancies by adding new marks.

Tip: I like to use different-coloured pencils for corrections.

Clone your pants

Step 4: Clone the back leg

The back leg has a dart, creating a curved fit around the bottom.

Mark the dart position on the inside of your trousers. (My dart was covered over on the inside by the pocket bag, so I marked this through from the right side with pins, then chalked on the wrong side.) Now refer to your garment analysis for the dart depth measurement. In my example it was 2cm (3/4in), making the total dart depth 4cm (11/2in).

To extract the back leg shape, approaching it in the same way as a sleeve gives the best results. Essentially, we are doing a quarter of the pattern at a time.

Fold the back trouser leg in half along the grainline, aligning the side seams, then pin along the fold from the hem to the waistband.

Cut a piece of pattern paper 20cm (8in) longer than the trouser length and approx. 30cm (12in) wider than the back trouser leg. In my example, this was 110 x 75cm (44 x 291/2in). Mark up your balance lines, as before.

Line up the hemline of the trouser with the shorter balance line, as before, then align the folded centre line of your trouser back with the longer balance line (the grainline) and anchor in place.

Keep the hem square to the shorter balance line and anchor along the hem. Then anchor the knee and thigh points, as before.

Copy your Clothes book

Work all the way up to the waist. Allow the top area to swing away from the grainline on the paper by half the measured depth of the dart. Anchor and mark its position.

Now anchor the upper area, and across the waist.

Create a trousers sewing pattern

Use a tracing wheel or a large pin to transfer all the seamlines through to the paper. As we’re working through thicker layers, work in short bursts.

Trace a pattern from your existing clothes

In the thicker areas, peel back small sections at a time to make sure you have transferred the seams to the paper and re-do if necessary.

Trace the knee and thigh balance lines.

Carefully remove the trousers without unpinning the centre fold. Mark over the outline you just traced, and the knee and thigh lines.

Flip the back trouser leg over to extract the other side, again lining up the hem with the short balance line and the folded centre with your grainline.

How to sew trousers

Working in the same way as before, smooth across the trouser at the key measurement areas (hem, knee and thigh), making sure the chalked lines do not tip up or down as you anchor them in place.

Again, in the upper area, the folded edge won’t lie flush with the vertical balance line, so let it swing away from the line by half the measured depth of the dart. Pinch a little pleat just below the dart, to make the trouser lie flatter below the dart and then anchor the hip area in place.

Anchor across the waistline, as before.

Trace the seamlines, including the dart, with a tracing wheel or pin.

Mark over the pin pricks with a coloured pencil.

How to move a dart

Step 5: Re-draw the dart in its correct position

The ‘dart space’ created during the cloning process is not in the correct position. Draw new dart legs either side of the correct, marked position on your pattern. In my example the temporary dart space measured 4cm (11/2in), so this will be the width of the new dart, too.

Working in the same way as for the front, compare all the key measurement lines from the actual garment to the cloned pattern, and mark any discrepancies.

Tracing the pattern from a pair of trousers

Step 6: Walk the seamlines on front and back legs

Before moving on to cloning the rest of the trouser pieces, it’s important to walk all the seamlines of the front and back trouser leg pattern pieces because they are used later to true/draft and walk other pattern pieces; in particular, ensure there are smooth curves running around the waistline and through the crotch curve.

Use the hem as the starting point to walk the trouser leg seams – it’s easier to correct at the crotch curve.

Lay the front leg pattern over the back leg along the inside leg (inseam), anchoring them together at the hem, then carefully walk the two pattern pieces along the entire seam. If the knee line or thigh line don’t match up, make a mark to correct them.

At the crotch, you may find that the seams are different lengths. Adjust as necessary. Once you’re happy with the base of the crotch curve, use your curved ruler to ensure the entire curve of the crotch is a nice, smooth shape.

How to trace the crotch of trousers

Walk the outside leg seam in the same way, again starting at the hem and working up to the waist.

It’s important to create a nice, smooth connection where the side seams meet at the waist. Use your curved ruler to smooth off any points or sharp dips and ensure both legs are the same length at this point.

See part 2 for the rest of this tutorial

To learn how to replicate other favourite garments in your wardrobe click the book cover below to order a copy of Clone Your Clothes.