Calculate collar size, neck circumference, or ease allowance by entering any two measurements to find the missing value in inches, cm, ft, or m.
Related Calculators
- Foot Width Calculator
- Short Or Long Torso Calculator
- Height to Hip Width Calculator
- Pleated Skirt Calculator
- All Everyday Life and Education Calculators
Collar Size Formula
The collar size is the neck circumference plus an ease allowance. The ease allowance is the extra room added so the collar is not tight against the neck.
CS = NC + EA
- CS = collar size
- NC = neck circumference
- EA = ease allowance
The calculator can solve for any missing value when you enter the other two:
NC = CS - EA
EA = CS - NC
- Calculate collar size: adds your neck circumference and ease allowance.
- Calculate neck circumference: subtracts the ease allowance from the collar size.
- Calculate ease allowance: subtracts the neck circumference from the collar size.
All values are converted to inches internally, then converted back to the unit you selected.
Typical Collar Ease Allowance
Use these ranges as general guidance. The right ease depends on fabric, collar style, and how snug you want the collar to feel.
| Fit preference | Typical ease allowance | Use case |
|---|---|---|
| Snug | 0.25 to 0.5 in | Close-fitting collars, costumes, fitted patterns |
| Standard | 0.5 to 1 in | Most shirts and casual collars |
| Loose | 1 to 1.5 in | Comfort-focused garments or thicker fabrics |
Common Collar Size Unit Conversions
| Measurement | Equivalent |
|---|---|
| 1 inch | 2.54 cm |
| 1 foot | 12 inches |
| 1 meter | 39.3701 inches |
| 40 cm | 15.748 inches |
Example Collar Size Calculations
Example 1: Calculate collar size
You measure a neck circumference of 15.5 in and want 0.75 in of ease.
CS = NC + EA
CS = 15.5 + 0.75 = 16.25 in
The collar size is 16.25 in.
Example 2: Calculate ease allowance
You have a collar size of 42 cm and a neck circumference of 40 cm.
EA = CS - NC
EA = 42 - 40 = 2 cm
The ease allowance is 2 cm.
FAQ
How do you measure neck circumference for collar size?
Wrap a flexible measuring tape around the base of the neck where the collar normally sits. Keep the tape level and close to the skin, but do not pull it tight. That measurement is the neck circumference. Add your chosen ease allowance to get the collar size.
What ease allowance should you use for a shirt collar?
A common shirt collar ease allowance is about 0.5 to 1 inch, or about 1.3 to 2.5 cm. Use less ease for a tighter fit and more ease for a looser or more comfortable fit.
Why does the calculator reject some values?
The calculator does not allow negative measurements. It also prevents results where the calculated neck circumference or ease allowance would be negative. For example, if collar size is smaller than neck circumference, the ease allowance would be negative, which is not physically useful for sizing a collar.
