How to adapt a pants pattern

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Why should you alter a pants pattern?

More than any other garment, pants must perfectly fit one’s morphology. If you’re making a pants pattern for someone, you’ll certainly have to adapt your pattern to avoid any alteration of the final garment.

Adapt a pants pattern can be tricky


As ready-to-wear measurements are born from statistics, they are not mirroring true measures of your client your are making the pattern for.


Alter pants pattern: what is most important?

Pants must fit exactly at the waist, you don’t have to add any ease there. Use waist measure or hip bone value if the pants has a low waist.

Tip: If you are working with thick fabric, you’ll have to add about 2 cm at the waist because of seams thickness.

Tip: Keep in mind that ease value has to be divided between each piece of the pants pattern, thus you have to add (or take off) a quarter of this value each time.

When altering along the full hips line, it’s important to add volume, also called “ease”, so your pants will “fall down” prettily along your clients sides with no ugly underwear crease. If your fabric has a fluid hand, you’ll have to add even more ease. It’s usual to add about 6 to 8 cm at full hips.

Back crotch line will be flattened or dipped according to your client’s bottom shape.


Alter the pattern along the sides

Take good care to alter your pattern symmetrically on front and back pieces. Draw identical curves on each pieces because they will be sewn together. It’s the only way to get a nice pants shape.


The pants length

It’s difficult to know the exact pants length when you draw its pattern. It’s only when your client will wear the pants with appropriate shoes and after the garment has found its place on her body, that you will know the exact length of the pants. It’s wise to draw a medium length pattern and add a large hem.


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