# Math Made Easy! How to Find the Surface Area of a Cylinder

## Geometry Tutorial

Total Surface Area of a Cylinder

For high school geometry students that are not really "fans" of the geometry subject, it is problems like finding the surface area of a cylinder that often cause kids to shut their text books and give up or find a geometry tutor.

But, don't panic just yet. Geometry, like many types of math, is often so much easier to understand when broken down into bite-sized pieces. This geometry tutorial will do just that - break down the equation for finding the surface area of a cylinder into easy to understand portions.

Be sure to follow along the cylinder surface area problems and solutions in the Geometry Help Online section below, as well as to try out the Math Made Easy! quiz.

## Equation for Total Surface Area of a Cylinder

S.A. = 2πr2 + 2πrh

Where: r is the radius of the cylinder and h is height of the cylinder.

Before beginning be sure you understand the following geometry tutorials:

## Use Familiar Objects to Visualize Geometric Shapes

Admittedly, the formula for the surface area of a cylinder isn't too pretty. So, let's try to break the formula apart into understandable pieces. A good math tip is to try to visualize the geometrical shape with an object with which you are already familiar.

What objects in your home are cylinders? I know in my pantry I have a lot of cylinders - better known as canned goods.

Let's examine a can. A can is made up of a top and bottom and a side that curves around. If you could unfold the side of a can it would actually be a rectangle. While I am not going to unfold a can, I can easily unfold the label around it and see that it is a rectangle.

Now you can visualize the total surface area of a cylinder (can):

• a can has 2 circles, and
• a can has 1 rectangle

In other words, you can think of the equation of the total area of a cylinder as:

S.A. = (2)(area of a circle) + (area of a rectangle)

Therefore, in order to calculate the surface area of a cylinder you need to calcuate the area of a circle (twice) and the area of a rectangle (once).

Let's look at the total surface area of a cylinder equation again and break it down into easy to understand portions.

Area of Cylinder = 2πr2(portion 1) + 2πrh (portion 2)

• Portion 1: The first portion of the cylinder equation has to do with the area of the 2 circles (the top and bottom of the can). Since we know that the area of one circle is πr2 then the area of two circles is 2πr2 . So, the first part of the cylinder equation gives us the area of the two circles.
• Portion 2: The second portion of the equation gives us the area of the rectangle that curves around the can (the unfolded label in our canned good example).We know that the area of a rectangle is simply its width (w) times its height (h). So why is the width in the second portion of the equation (2πr)(h) written as (2πr)? Again, picture the label. Notice that the width of the rectangle when rolled back around the can is exactly the same thing as the circumference of the can. And the equation for circumference is 2πr. Multiply (2πr) times (h) and you have the area of the rectangle portion of the cylinder.

## Geometry Help Online: Surface Area of Cylinder

Check out three common types of geometry problems for finding the surface area of a cylinder given various measurements.

## Math Made Easy! Quiz - Surface Area of a Cylinder

For each question, choose the best answer. The answer key is below.

1. What is the surface area of a cylinder with a radius of 3 cm. and a height of 10 cm.?
• 165.56 cm.
• 165.2 sq. cm.
• 244.92 sq. cm.
2. What is the height of a cylinder with a surface area of 200 sq. in. and a radius of 3 in.?
• 5.4 in.
• 7.62 in.
• 4 in.

1. 244.92 sq. cm.
2. 7.62 in.

## #1 Find Surface Area of Cylinder Given the Radius and Height

Problem: Find the total surface area of a cylinder with a radius of 5 cm. and a height of 12 cm.

Solution: Since we know r = 5 and h=12 substitute 5 in for r and 12 in for h in the cylinder's surface area equation and solve.

• S.A. = (2)π(5)2 + (2)π(5)(12)
• S.A. = (2)(3.14)(25) + (2)(3.14)(5)(12)
• S.A. = 157 + 376.8
• S.A. = 533.8

Answer: The surface area of a cylinder with a radius of 5 cm. and a height of 12 cm. is 533.8 cm. squared.

## #2 Find the Surface Area of a Cylinder Given the Diameter and Height

Problem: What is the total surface area of a cylinder with a diameter of 4 in. and a height of 10 in.?

Solution: Since the diameter is 4 in., we know that the radius is 2 in., since the radius is always 1/2 of the diameter. Plug in 2 for r and 10 for h in the equation for the surface area of a cylinder and solve:

• S.A. = 2π(2)2 + 2π(2)(10)
• S.A. = (2)(3.14)(4) + (2)(3.14)(2)(10)
• S.A. = 25.12 + 125.6
• S.A. = 150.72

Answer: The surface area of a cylinder with a diameter of 4 in. and a height of 10 in. is 150.72 in. squared.

## #3 Find the Surface Area of a Cylinder Given the Area of One End and the Height

Problem: The area of one end of a cylinder is 28.26 sq. ft. and its height is 10 ft. What is the total surface area of the cylinder?

Solution: We know that the area of a circle is πr2 and we know that in our example the area of one end of the cylinder (which is a circle) is 28.26 sq. ft. Therefore, substitute 28.26 for πr2 in the formula for the area of a cylinder. You can also substitute 10 for h since that is given.

S.A. = (2)(28.26) + 2πr(10)

This problem still cannot be solved since we do not know the radius, r. In order to solve for r we can use the area of a circle equation. We know that the area of the circle in this problem is 28.26 ft. so we can substitute that in for A in the area of a circle formula and then solve for r:

• Area of Circle (solve for r):
• 28.26 = πr2
• 9 = r2(divide both sides of the equation by 3.14)
• r = 3 (take the square root of both sides of the equation)

Now that we know r = 3 we can substitute that into the area of the cylinder formula along with the other substitutions, as follows:

• S.A. = (2)(28.26) + 2π(3)(10)
• S.A. = (2)(28.26) + (2)(3.14)(3)(10)
• S.A. = 56.52 + 188.4
• S.A. = 244.92

Answer: The total surface area of a cylinder whose end has an area of 28.26 sq. ft. and a height of 10 is 244.92 sq. ft.

## Do you need more geometry help?

If you have another specific problem you need help with related to the total surface area of the cylinder please ask in the comment section below. I'll be glad to help out and may even include your problem in the problem/solution section above.

Kristin Trapp (author) from Illinois on July 23, 2012:

Thanks so much Vellur. It's good to know this explanation was easy to follow - that always should be the goal when it comes to math. Thanks again.

Nithya Venkat from Dubai on July 23, 2012:

Very well explained. You have made it very easy. Voted up.

Kristin Trapp (author) from Illinois on March 12, 2012:

B. Leekley - I think you wonder the same things as a lot of math students, "what am I ever going to use this for?" You're right understanding how to figure out what size pizza is the cheapest per slice is a practical application of math. In order to figure out that you would want to divide the price of each pizza size by the area of the circle for each size. That way you would get the cost per square unit.

Brian Leekley from Bainbridge Island, Washington, USA on March 09, 2012:

Interesting hub -- I liked the aha of realizing that the sides of a cylinder are a rectangle -- but in what situation would knowing the total surface area of a cylinder be of practical use? What I often wonder is which size pizza is cheapest on a per square unit basis?

Kristin Trapp (author) from Illinois on November 29, 2011:

Teaches12345 - I would have loved to have taught high school geometry, but I am not a certified teacher. I just have always loved math, and often had to find more obvious ways of helping my kids understand some geometry and math concepts than what the textbooks provide. Thanks so much.

Kristin Trapp (author) from Illinois on November 29, 2011:

Homesteadbound - Thanks so much for stopping by again. Now, I am not sure if this was "ingenious" but it is a fun way to learn.

michifus on November 28, 2011:

Great hub!

Dianna Mendez on November 28, 2011:

I wish I would have had you for geometry in high school. You make it simple to understand, breaking it down and then building the interest and skill. The visuals are so helpful...voted up!

Cindy Murdoch from Texas on November 28, 2011:

Ktrapp - as I stated earlier, this was so ingenious. Great hub!

Congratulations on hub of the day!

Kristin Trapp (author) from Illinois on November 28, 2011:

Beth811 - Visualizing math always helped me learn better. I remember years ago pulling a can out of the pantry to show my daughter what her geometry problem was asking and she "got it" easily. I hope it helps other kids (or parents). Thanks for stopping by.

Kristin Trapp (author) from Illinois on November 28, 2011:

Xethonxq - I would've loved to have had the opportunity to tutor kids in math. I mostly just helped my own. Thanks taking the time to comment.

Kristin Trapp (author) from Illinois on November 28, 2011:

Thanks emdi.

Beth Arch from Pearl of the Orient Seas on November 28, 2011:

Wow, you made the solution easier to understand. I'm impressed with your analogy between the can and the label around it.

Well said! Congrats on Hub of the Day!

xethonxq on November 28, 2011:

Wow!!! Can you come and tutor my kid? lol :) Thanks for the hub ktrapp!!

emdi on November 28, 2011:

So cool idea.

Kristin Trapp (author) from Illinois on November 28, 2011:

Thanks everyone for all the very nice comments (except Arlene - haha!).

William - I appreciate your suggestion and did add the word "total" so as to distinguish these types of problems from lateral surface area problems. Thanks for taking the time to comment.

DzyMsLizzy - I like that idea of giving yourself a "pardon from math." - very funny.

Rebecca Mealey from Northeastern Georgia, USA on November 28, 2011:

I love it when teachers make things fun.....then they automatically become easier to understand. Great job!

Congraulations!

Jennifer Essary from Idaho on November 28, 2011:

Excellent Hub! Voted up!

sestasik on November 28, 2011:

Congrats on hub of the day. This is a brilliant way to explain a complicated area formula!

arusho on November 28, 2011:

Liz Elias from Oakley, CA on November 28, 2011:

Congratulations on Hub of the Day.

I'm not a math person, and you lost me at "portion 2." My brain hurts. LOL (And RE: William Norman's comment--that was my first thought--what if it's an open-ended cylinder without lids--such as a section of pipe? Then only the "flattened out" cylinder dimensions would apply, eh?) :-)

Very well done explanation, anyway, for those who actually may still be studying the subject. At age 63, however, I've given myself a pardon from doing any more math problems. I'm a writer--I don't need math.

Even if I am a math dummy--I've still voted this as up, interesting and useful--because it will be useful to many!

Arlene V. Poma on November 28, 2011:

I repeat: Auuuuuuuuuuuuuuuuuuuuuuuuuuuuuugh!!!

Carolyn Sands from Hollywood Florida on November 28, 2011:

I bet you are a genus. Good job explaining. Even I managed not to get completely lost.

William Norman from Cross Plains, Texas on November 28, 2011:

Good job, but I would recommend adding the word "total" before "surface area", as many problems ask for the "lateral surface area" that does not include the area of the two circles.

Deborah Neyens from Iowa on November 28, 2011:

I told you this before, I think your Math Made Easy series is brilliant. Congrats on Hub of the Day!

Kristin Trapp (author) from Illinois on November 28, 2011:

Applecsmith - Thank you. Sometimes I think creativity is the best way to help understand math concepts.

Kristin Trapp (author) from Illinois on November 28, 2011:

RTalloni - Thanks. I appreciate you taking the time to comment again!

Carrie Smith from Dallas, Texas on November 28, 2011:

This is a very creative way to break down geometry. Congrats on being the hub of the day!

RTalloni on November 28, 2011:

I know I commented a while back, but just wanted to say congrats on your well-deserved Hub of the Day! :)

Kristin Trapp (author) from Illinois on November 28, 2011:

Thank you everyone for the "congratulations." It makes me happy to know that this brought back memories for some people and others think that it will be useful for students.

Patricia Scott from North Central Florida on November 28, 2011:

Congratulations...hub of the day, that s cool!!

Clever use of materials to bring home this concept to kids.

Some 'get it' right away; some do not. For those who do not this will be the way to begin. Some of the 'get it' kids may prefer learning this way as well.

Leah Lefler from Western New York on November 28, 2011:

What a great way to teach geometry - I love hands-on math lessons! I am bookmarking this one for my kids, too - granted, they're only 4 and 6 now, but this will definitely come in handy in a few years!

HendrikDB on November 28, 2011:

It lets the grey stuff works overtime!

Sondra from Neverland on November 28, 2011:

Oh, I WILL be a fan and this WILL be bookmarked for my daughters!!! Not only is this in simple terms but it is wonderfully laid out. You are a gem for sure :)

softhard from Kathmandu on November 28, 2011:

Congratulations on hub of the day.

Excellent job, very creative, that you actually wrote the nice piece of whole article beginning with a simple math formula. Actually on school days, geometry had been easiest subject for me because i also used similar kind of techniques to remember these kinds of formula. You remind me of those old days. Math students will love this article.

thearbiter0808 on November 28, 2011:

When was the last time I came across this formula? Many thanks to you for bringing back all the memories, both good and bad. On top of that, congratulations for the hub of the day!

David Stillwell from Sacramento, California on November 28, 2011:

ktrapp: Congratulaitons on hub of the day. This is truly a great hub... even I did well on the quiz!

Kristin Trapp (author) from Illinois on October 28, 2011:

You are so kind StayPos. And I agree, there is a lot of noise and confusion in our world making it difficult to learn a range of topics. I have found with a lot of things, that the complex is usually made up of a series of simpler things - making it seemingly complex only at first glance.

StayPos from Florida, USA on October 28, 2011:

Ktrapp,

This hub is a great example of how using creativity helps us transform "complex" things into much simplier understanding! It's a desperately needed attribute for cutting through the noise and confusion in our world today! Bravo!

Voted Up and Awesome!

Kristin Trapp (author) from Illinois on October 27, 2011:

Thanks Simone for the enthusiastic comment. I'm not sure my old geometry teacher during the early 80s would go-for this lesson style. He actually made us read a horrible book about a two-dimensional world. I think it was called Flatland - a horrible thing to do to high school kids, and no way to teach math!

Simone Haruko Smith from San Francisco on October 27, 2011:

This is SO NEAT!! I should share this with my old geometry teacher- this would make for such a fantastic lesson!

Kristin Trapp (author) from Illinois on October 27, 2011:

That's funny Sunshine, but it says "made easy." It still involves a little work.:)Thanks for taking a look and commenting.

Linda Bilyeu from Orlando, FL on October 27, 2011:

Hi ktrapp! Your title says easy...did I miss something? Haha! Numbers and I do not get along. Fantastic hub though!

Kristin Trapp (author) from Illinois on October 26, 2011:

Thanks RTalloni - I think you may be the first person to comment that math hubs make you smile :) Thanks.

RTalloni on October 26, 2011:

Still loving your math hubs--they are interesting and a great reference tools for a wide variety of people. And they make me smile. :)

Kristin Trapp (author) from Illinois on October 25, 2011:

Your funny blog8withJ - very far from genius, but I do like finding ways to explain math in understandable terms. Thanks for commenting.

blog8withJ on October 25, 2011:

Oh my...you're a math genius. I think Math don't like me as I don't like it...Lol---

Kristin Trapp (author) from Illinois on October 24, 2011:

Oh, thanks homesteadbound. I do think I would have really enjoyed being a math teacher. I'm glad to know this little tutorial made solving the surface area of a cylinder look easy. That was my goal in writing it and hopefully it will one day help that random kid who is stuck on their math homework.

Cindy Murdoch from Texas on October 24, 2011:

Taking the paper off the can to explain the concept was ingenious. Are you sure you shouldn't be a math teacher. You make it look so easy. Great hub!

Kristin Trapp (author) from Illinois on October 23, 2011:

Hey Arlene. I'm honored to have taken you down memory lane back to high school geometry. The good news is you passed and perhaps discovered your passion for writing.

Arlene V. Poma on October 23, 2011:

Ay, yi, yi, k! I could have used your help back in the early 70s when I got a D- in geometry. Thanks for the memories! That's when I discovered that English was more of my thang!

Kristin Trapp (author) from Illinois on October 23, 2011:

Joseph De Cross from New York on October 23, 2011:

Like the others..you made this geo class easier than my Teacher Ktrap!

LORD

susan54 on October 23, 2011:

great way to explain math.

lavender3957 on October 23, 2011:

Wow, did I need you back in my days in school. This was made so simple to follow and I finally got it after 30 years with your hub. Thanks for sharing. Where were you in 72?

Stephanie Das from Miami, US on October 23, 2011:

Its cool that you could break it down like that. I like the can example. When I saw the title of this hub, I realized that I had completely forgotten everything from geometry class, and this reminded me again. Good work.

Louise Fiolek from Calgary, AB, Canada on October 23, 2011:

Oh how clever, ktrapp! You explained this so well. Thank you!

Voted up / interesting / useful

Kristin Trapp (author) from Illinois on October 23, 2011:

Thank you randomcreative. That's a nice compliment - especially coming from a teacher!

Rose Clearfield from Milwaukee, Wisconsin on October 23, 2011:

Great resource for students and math teachers!

Kristin Trapp (author) from Illinois on October 23, 2011:

Thank you Tina. I hope this helps your daughter, or at least helps make math more approachable for her.

Christina Lornemark from Sweden on October 23, 2011:

What a great way to explain math! It makes such a difference to "see" the problem and also see that usual things at home can be used as help! I will show this hub to my daughter who thinks math is a little difficult! Voted up, useful!

Tina

Kristin Trapp (author) from Illinois on October 23, 2011:

Billabongbob - It's not too often that most adults have to figure out the area of a cylinder, but for students it can be especially frustrating, especially when a teacher is rapidily writing formulas and numbers on the blackboard. I think kids would do better in math if they had less fear of the subject and could stop and think and picture what they are actually being asked to solve. Thanks for your feedback.

Kristin Trapp (author) from Illinois on October 23, 2011:

Thank you Man from Modesto. I have never seen numbered pasta, but you got me thinking - spaghetti -Os are circles so I guess they'll do too.

billabongbob from South Wales, UK on October 23, 2011:

It's been a long time since I've had to work out the area of a cylinder, but this brought it all back. Brilliantly explained, in simple terms.

Great work, well done!!!

Man from Modesto from Kiev, Ukraine (formerly Modesto, California) on October 22, 2011:

Very nicely done! Would have been cute to use Heinz numberetti (number pasta in a cylinder).