## Is There A Thread To Figure Out Geometry Of A Cake?

Decorating By HowCoolGomo1 Updated 1 Dec 2009 , 3:27pm by erinalicia

Before it ends up on Cakewrecks, Leno or Letterman...oh heaven help us, maybe Lopez.

Before the moderators, send me to general.

This is a valid question. Cake involves understanding the dynamics of all the math fields.

Chemistry is absolute, it must taste good and then physics has to get some attention. NO one wants a cake that tilts, plus all the other crap that goes wrong and does go wrong. Might I add at the most inconvenient times.

Then I have to get to the Algebra. The nuts and bolts of cost, time and artistry. I think that takes the quadratic equation.

Any way my question

Has anyone ever conquered the formula C (circumference)= 3.14(pi or 22/7)*D(diameter)?

C=3.14*D

If they have, can you tell me if it's accurate? Since I suck in geometry can you tell me how to convert it lbs or kgs?

I and geometry never got along. My brain says this is a simple algebra question.

Oh, yes I do own a flexible tape.

I ask because, I JUST HAVE TO ASK WHAT THE HE$$ IS KERNING?

I use circumference ALL the time to figure out how long to make a fondant ribbon. Pi * diameter always works IF you remember that a 6" cake is actually 7" with the icing on it.

Kerning is the process of adjusting the space between the letters in a word.

l i k e t h i s.

Bonus: Who knows what leading is? (lead like the metal)

(I know.)

leading >> the thin metal strips originally placed between hand set lines of type to control the amount of spacing between lines. not to be confused with concept of double or triple spacing where a full line or two full lines of type are left blank. A much more subtle way to gently expand the vertical space a block of type takes up.

today it's done by software (go InDesign!) and can be adjusted very easily along with kerning to make a shortish story fill the assigned space in the school newspaper (thankfully this year haven't had to use it much, yet)

Correctamundo Doug! Reportedly also related to "get the lead out." Hurry up, take the lead strips out, we gotta squeeze in more stuff.

as to the original post:

EXCEL spreadsheet attached -------

---

as for measuring around a cake ---

strips printer paper taped together, wrapped & marked.

---

as for conversion into lbs and kgs.

that gets into volume and DENSITY (not going there!)

**leah_s**

Reportedly also related to "get the lead out." Hurry up, take the lead strips out, we gotta squeeze in more stuff.

if only that were true of the school paper -- ours is: hurry up, write something, find a pic, find clip art -- we got a HOLE to fill!

(you'd think HSers would be able to easily fill 8 pages given how much they love to chat on the phone, text, and generally run their mouths!)

**leah_s**

I use circumference ALL the time to figure out how long to make a fondant ribbon. Pi * diameter always works IF you remember that a 6" cake is actually 7" with the icing on it.

Kerning is the process of adjusting the space between the letters in a word.

l i k e t h i s.

Bonus: Who knows what leading is? (lead like the metal)

(I know.)

Now that just made perfect sense to me.

Thank you!

There was a gal here on CC a few years ago who went through all the geometry of how square cake pans hold x% more batter than round pans, and how to figure all that out, etc. etc. But ask me who she is or where to find those posts? Nada!

**sherrycanary62**

cake decorating involves math?

(hangs head, shakes it sadly).....I'm doomed

Don't worry we'll hold your hand.

There's always the wilton cake dividing wheel, for the math challenged or the lazy (that's me) among us, if you're trying to find the circumference so that you can see how to evenly divide into sections. If you're wanting the circumference for a fondant ribbon, I always just multiply the diameter by 3 and figure the other .14 will work itself out in the stretch

Circumference doesn't have anything to do with lbs or kgs. It would be measured in inches or centimeters.

Oh good. I like to help if I can, but I had (and still have) no idea what the question was.

Okay ... if I'm understanding the question correctly, then you're asking how to calculate the density (or weight) of your cake based on its circumference or on its diameter, right? (If I'm not understanding it correctly ... well then, just ignore me ). It's a little long-winded, so here goes - but don't say I didn't warn you!

Remember that your density (d) = mass (m)/volume (v)

and your v = length (l) * width (w) * height (h) (for a square or rectangle ... look below for a typical round cake).

1.- For a round cake, figure out your radius (this is without counting the extra inch for icing that leah_s spoke of, as an inch of icing will not weigh what an inch of cake does); so for a 6 inch cake, the radius truly is 3 inches.

2.- Measure the height of your bare cake.

3.- Multiply your height by Pi.

4.- Square the radius. (Multiply the radius by itself.)

5.- Multiply the product from Step 3 by the product of Step 4. This will give you your unit of volume, and it will be a cubic unit (whether you calculated it in inches or centimeters, it will be cubic).

6.- Now, as we don't have a standard cake density and all recipes are different, here's where you have to do a little personalized math. Cut a piece of your typical base recipe for cake (be it a scratch, WASC, or whatever cake) that is the size of one cubic unit (i.e. cut one inch by one inch by one inch of cake for cubic inches, ditto for centimeters) and weigh that on your kitchen scale. THAT is your cake's Density. Once you've weighed once, you can use the same weight every time you bake, supposing you use a similar recipe, and you don't need to reqeigh with each session.

7.- Multiply your Volume result from Step 5 by your Density however much one cubic inch of your recipe weighs, and that will give you the Mass (close enough to weight for all intents and purposes) of your cake in your chosen weight units. This will give you your un-iced cake's weight. Obviously much easier to do if you have a square cake.

LOL! Hope people don't throw cake pans at my head for that!

wow, this whole conversation just 747'd me!

If I had read this before making my first cake, I'd think I was too dumb to make a cake! I am impressed, folks, with the question and the answers!

Yeah, it's amazing what you find if you think back to the dark confines of your mind where you store things like Physics and Geometry and Calculus! I use organic and inorganic chemistry on a daily basis, but hadn't thought about cylinders in awhile . That being said ... I don't think I'd ever apply the stinking formulas to a real cake .

Love the questions, and more importantly the answers...does it make sense? He** NO! But the fun it has created sure beats the drama on some of the other threads!!!

Now, let's figure out some formula for making perfect corners!!

And to think we didn't believe our teachers in school when they told us we would need to use math in the real world. lol

sandy

*Chuckling* Oh, don't get my geeky mind started! You'll have me calculating out the exact velocity at which you can pipe whipped buttercream vs ganache, and the deceleration rates of both when you want to stop! You don't know the kind of monster that lives in my head!!!

**emiyeric**

Okay ... if I'm understanding the question correctly, then you're asking how to calculate the density (or weight) of your cake based on its circumference or on its diameter, right? (If I'm not understanding it correctly ... well then, just ignore me ). It's a little long-winded, so here goes - but don't say I didn't warn you!

Remember that your density (d) = mass (m)/volume (v)

and your v = length (l) * width (w) * height (h) (for a square or rectangle ... look below for a typical round cake).

1.- For a round cake, figure out your radius (this is without counting the extra inch for icing that leah_s spoke of, as an inch of icing will not weigh what an inch of cake does); so for a 6 inch cake, the radius truly is 3 inches.

2.- Measure the height of your bare cake.

3.- Multiply your height by Pi.

4.- Square the radius. (Multiply the radius by itself.)

5.- Multiply the product from Step 3 by the product of Step 4. This will give you your unit of volume, and it will be a cubic unit (whether you calculated it in inches or centimeters, it will be cubic).

6.- Now, as we don't have a standard cake density and all recipes are different, here's where you have to do a little personalized math. Cut a piece of your typical base recipe for cake (be it a scratch, WASC, or whatever cake) that is the size of one cubic unit (i.e. cut one inch by one inch by one inch of cake for cubic inches, ditto for centimeters) and weigh that on your kitchen scale. THAT is your cake's Density. Once you've weighed once, you can use the same weight every time you bake, supposing you use a similar recipe, and you don't need to reqeigh with each session.

7.- Multiply your Volume result from Step 5 by your Density however much one cubic inch of your recipe weighs, and that will give you the Mass (close enough to weight for all intents and purposes) of your cake in your chosen weight units. This will give you your un-iced cake's weight. Obviously much easier to do if you have a square cake.

LOL! Hope people don't throw cake pans at my head for that!

I think I love you...

**indydebi**

wow, this whole conversation just 747'd me!

If I had read this before making my first cake, I'd think I was too dumb to make a cake! I am impressed, folks, with the question and the answers!

:rofl2:

I was a teacher at a private school last year and I kept telling them, don't listen when people say you'll never use your math....YOU WIll!!

Then they said......how?? I informed them that I need to use the formula for figuring out the area of a triangle over the summer because my garden bed HAPPENS to be a triangle and I wanted to mulch it. I was able to figure out exactlly how much mulch I needed to buy and it turned out perfectlly!!

Then I told them how I needed chemistry for baking the cakes and geometry for adding ribbons and figuring out scallops and drop strings and so forth. They were amazed!! I told them "never say never, because you have NO IDEA what God has in store for your life"

I struggled with Geometry and Fractions the most when I was in school and what 2 things do I use THE MOST with cake decorating...........of course!!! lol

and this is all to figure out how much a cake weighs? why? just use a digital scale.

as for using pi * diameter that's useful for figuring out how much ribbon you need to go around your cake or boards.

And Scientific Calculators are a God Send! Do you really think I would use a pencil & paper?

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