Length Question

Decorating By dreamtreats Updated 10 Jun 2010 , 5:56pm by mpetty

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dreamtreats Posted 10 Jun 2010 , 5:31pm
post #1 of 7

I seem to have math issues when trying to figure out how long to roll out fondant when cutting a stripe for cakes.

So heres what I need:
If i have an 8" cake how long should a 'ribbon base' be?
6" cake?
and so on? Never get it right and me a seams dont get along.

6 replies
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CrazyCatLady Posted 10 Jun 2010 , 5:43pm
post #2 of 7

pi X diameter = circumference


3.14 X 8" = 25.12"

3.14 x 6" = 18.84"

just multiply whatever size the cake is times 3.14 (pi).

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jqorso Posted 10 Jun 2010 , 5:45pm
post #3 of 7

For round cakes:


Where D is the diameter of the cake and PI = 3.14 (it's enough sig figs for cake).

So for an 8" cake you need a minimum of 25.12 inches (8"*3.14). Round up though to make sure you have wiggle room for extra frosting and such. It's better to have too much than not enough.

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carolyn1489 Posted 10 Jun 2010 , 5:47pm
post #4 of 7

Im a big math nerd so....

The length you need is the circumference of the circle, which is just a measurement around the circle.

The equation for it is d(diameter)*pi

Diameter is easy, that is the size of your cake pan=8inches

Pi is 3.14

Just multiply the 2= 25.12 inches

To be on the safe side, always add a few more inches!

For your second cake, you need 18.84 inches.

Hope that helps!

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robyndmy Posted 10 Jun 2010 , 5:49pm
post #5 of 7

I'm terrible at math myself, so I always just keep a sewer's measuring tape in the kitchen (those flexible ones). Comes in handy for things just like that, length, amount of rolled fondant I need, etc. HTH!

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melmar02 Posted 10 Jun 2010 , 5:50pm
post #6 of 7

Sorry to hijack, but some of my co-workers were just talking about how they never use math in our job or their lives. I piped up and said I use geometry and algebra all the time for cakes. They were a little in awe that I knew how to find the volume of my cake pans and could convert it to the number of batches of cake I need for each one using ratios. That was the "made me feel smart" moment of the day.

Dreamtreats - you can also measure around your cake with a flexible tape measure or string and roll your fondant out to that length.

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mpetty Posted 10 Jun 2010 , 5:56pm
post #7 of 7
Originally Posted by melmar02

I piped up and said I use geometry and algebra all the time for cakes.

LOL, which is why, now that I'm doing cakes, I keep kicking myself for not paying attention in Math class!

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