How do I calculate the volume of water in my fish tank?

Hi,
I have an octagonal fish tank. Each glass panel is 12cm wide %26 28cm tall %26 the width of the tank is 30cm.

How do I calculate the volume of water the tank holds, in litres?

Thanks.
Answers:
I am SOOO going to cheat here. I always use the url below to calculate. All you need to measure is the height and the width of each side and how many sides you have (in your case..8) and it will figure it out in both metric or non-metric. In this case? 16.13 litres.

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Use something you know the volume of such as a measuring cup then pour the water in liter by liter.

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Find the square area of the octagon and multiply by the height.
Liters ?? No idea I'm in the NEW world,, California
But it sounds like 10 gal.
Try a one liter Or 5L jug and fill it???
12 x 28 IS NOT an octagon

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Take the width of the tank from the middle of two sides (call this "h") and then the height of the water (call this "l") and the length of one of the eight sides can be "w". The tank is basically eight triangular prisms so the volume is 8*(.5*l*w*h).

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do a serch on yahoo for water volume calculater
there are free tools out there all you have to do is put the size in and it will tell you.

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http://askalanaquestion.com/calculating_...

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Lenth if the tank is 30cm so the apothem is 15 cm (assming the length is measured side to side (not corner to corner) and that the base is a regular octogon)

The perimeter is then 12 * 8 = 96 cm.

The formula for the area of a regular polygon is A = 1/2ap,

=1/2*15*96 (cm)

V= A*h = A*28cm

there you go

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Area of an octagon = 4.828 x (a x a) in which a is one of the sides.
Area = 4.828 x (12 x 12) = 695.23 sq cm


695.23 sq cm x 28 = 19,466.5 cu cm / 1,000 = 19.466 litres

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Try this link: http://home.comcast.net/~jdieck1/volcalc...

Not sure if it still contains octagonal calcs but with that small a volume you will be pretty safe adding about 6.8% to the hexagonal calc.

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Think of the tank as 8 triangles. The area for a triangle is 1/2 of the base x the height:

1) Find the measurement if one panel and divide that by 2 (= 1/2 base).
2) Measure the tank from the middle of one side to the middle of the opposite side and divide that by 2 (= height of one triangle).
3) Multiply the results of the first two steps (= area of one triangle).
4) Multiply the result of the last step by 8 (= area of the tank bottom).
5) Multiply the result of the last step by the height (= volume in cubic cm).
6) Multiply the result of the last step by 0.001 to convert to liters.

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WHAT ? are u guys like smart or something