Fabric Calculator

Umbrellas

Unit of Measurement
A. Radius (?)
One half of the umbrella's fabric diameter -- measure over a rib from one edge to the center point.
   
inches
B. Number of Gores (?)
The number of triangular pie shaped panels with seams radiating from the center (often 8 as in the image above and never less than 3).
   
3 to 20
Hem (?)
Finished width of the doubled hem all round the Umbrella. A one inch hem would add two inches of fabric to the length of each gore. This will be zero if a binding is used to finish the circumference of the umbrella.
   
inches
C. Open Diameter (?)
Measure the diameter of the opened umbrella if possible. This diameter will normally be roughly 10% less than twice the radius measured above. This measurement determines the shape of the umbrella "cone".
     
inches
Fabric Width (?)
Actual width of fabric (often 46, 54, or 60 inches -- 1168, 1372, and 1524 mm)
   
inches
Select Fabric Style:
(?)
No fabric pattern
(?)
Pattern runs along fabric length.
(?)
Pattern runs along fabric width.
Vent with Fly:
(?)
A 16 inch opening will be provided at the center with a 28 inch circular fly to cover it.
(?)
There will be no hole at the umbrella's center.