How to do a Fuller Abdomen or Seat Adjustment for Trousers - Fernway

This is a simple and quick pattern modification that can be used to adjust pull-on style pants for a fuller abdomen or seat.  Use your own measurements to customize the rise of the trousers for your preference and comfort.  

Here, we demonstrate the adjustment using the Fernway Culottes.  


  • Pattern pieces (we're using the Fernway Culottes)
  • Measuring tape
  • Scrap paper
  • Pencil
  • Ruler
  • Scissors


Use the Finished Garment Measurement Chart (in the pattern tutorial) as a guide.

To determine how much length to add to the rise of your trousers, use the following method to measure rise:

  • Tie a ribbon around your waist at the height you would like the waistband to sit. 
  • Place the end of the tape measure on the ribbon at the centre back, thread it through the legs, and bring it up to the ribbon at the centre front, keeping the bottom of the crotch/rise seam at the position you want it to sit between your legs (allowing for ease). 
  • Pull the tape measure up to meet the ribbon at the front and note the measurement.  

Compare the measurement from your body to the measurement on the chart.  If the measurement on the chart is smaller than your body measurement, or doesn't provide enough ease for a comfortable fit, then add the difference to the pattern front rise.  

For example, the size N Fernway Culottes have a rise of 39.2" (99.5cm).  Our sample sewist measures and finds that they need a rise of 42" (106.5cm) for a comfortable fit.  Calculate the difference between the two measurements to figure out how much to add:

Finished garment rise measurement 39.2" (99.5cm)
Sample rise measurement 42" (106.5cm)
Difference = amount to add 2.8" (7cm)

Note that the amount of ease required will vary depending on personal preference as well as the intended fit of the trousers.  The Fernway Culottes are intended to have a fair amount of ease in the rise.  

Adjust the pattern pieces

1.  Cut through the lengthen/shorten line on the Front pattern piece, stopping at the seam allowance on the side seam, leaving a bit of paper intact to create a pivot point 3/8" (1cm) from the pattern edge.  

Fuller Abdomen Adjustment for Trousers by Twig + Tale

2.  Pivot the front rise until it is lengthened the amount determined above.  In our example, this is 2.8" (7cm). 

Fuller Abdomen Adjustment for Trousers by Twig + Tale

3.  Place a piece of paper behind the pattern and tape it into place to secure the two pieces.  Blend the front rise so it is a smooth curve.  

Fuller Abdomen Adjustment for Trousers by Twig + Tale

The same method can be used to adjust the Back pattern piece for extra rise in the seat.  

Once your pattern piece is adjusted, continue to cut and sew as outlined in the tutorial.  We always recommend sewing a muslin to check the fit before cutting into your final fabric.  

Enjoy wearing trousers with a customized fit!

Read more T+T pattern adjustment tutorials here: