How to Calculate Negative Ease

Negative ease is a sewing technique used to create fitted garments by intentionally making the pattern pieces smaller than the actual body measurement. This guide explains how to calculate negative ease for accurate garment construction.

What is Negative Ease?

Negative ease, also known as fitted or tailored ease, is the opposite of positive ease. While positive ease adds extra fabric to create a looser fit, negative ease reduces the pattern size to create a tighter fit. This technique is commonly used in fashion design to create custom-fitted garments.

Negative ease is different from negative fit, which refers to a garment that's too small for the wearer.

When to Use Negative Ease

Negative ease is ideal for creating fitted garments such as:

Custom-made suits and jackets
Tailored dresses and skirts
High-end athletic wear
Special occasion wear

How to Calculate Negative Ease

Calculating negative ease involves determining how much smaller your pattern pieces should be compared to the actual body measurement. The process includes:

Measuring the body part accurately
Determining the desired fit level
Calculating the negative ease percentage
Adjusting the pattern size accordingly

Steps to Calculate Negative Ease

Measure the body part: Use a flexible measuring tape to get accurate measurements of the body part you're working with.
Determine fit level: Decide on the desired fit level (tight, snug, or fitted).
Calculate negative ease: Use the formula below to determine how much smaller your pattern should be.
Adjust pattern: Reduce the pattern size by the calculated negative ease amount.

Formula

Negative Ease Formula:

Negative Ease = (Body Measurement × Fit Percentage) - Body Measurement

Where:

Body Measurement = Actual measurement of the body part
Fit Percentage = Desired fit level (e.g., 0.95 for 5% negative ease)

The fit percentage determines how much smaller the pattern should be. Common negative ease percentages include:

5% negative ease (0.95 fit percentage)
10% negative ease (0.90 fit percentage)
15% negative ease (0.85 fit percentage)

Example Calculation

Let's calculate negative ease for a jacket sleeve with these measurements:

Body measurement: 34 inches
Desired fit: 10% negative ease (0.90 fit percentage)

Calculation:

Negative Ease = (34 × 0.90) - 34

= 30.6 - 34

= -3.4 inches

This means the sleeve pattern should be 3.4 inches smaller than the actual sleeve measurement to achieve a 10% negative ease fit.

Always test fit garments with negative ease to ensure the desired fit level is achieved.

FAQ

What is the difference between negative ease and positive ease?

Negative ease reduces pattern size for a fitted look, while positive ease adds extra fabric for a looser fit. Negative ease creates a tighter garment, while positive ease creates a more relaxed fit.

How much negative ease should I use?

The amount of negative ease depends on the desired fit. Common percentages range from 5% to 15%, with 10% being a good starting point for most garments.

Can I use negative ease for all garments?

Negative ease works best for fitted garments. For casual wear, positive ease is often more appropriate. Always consider the intended use of the garment when choosing ease.

How do I know if my negative ease calculation is correct?

Always test fit your garment after applying negative ease. If the fit isn't as expected, you may need to adjust the ease percentage or pattern adjustments.