# Thread: Cubic foot to gallons conversion

1. ## Cubic foot to gallons conversion

Okay, online conversion calculators and Skene's conversion tables tell me that one cubic foot of volume (12x12x12=1728 cubic inches) is equal to a little under 7.5 gallons of liquid.

I measured the dimensions of a gallon of water in one of your standard plastic buckets and it came to 9" diameter by 7.5" height in the approximate cylinder. Using Pi times R squared times height the cubic inches of a gallon are 3.14 X (4.5 x 4.5) x 7.5 = 477 cubic inches

1728 cubic inches (a cubic foot) divided by 477 cubic inches (my measured gallon) = 3.62 gallons per cubic foot... not 7.5

What gives? Did I miss multiplying by 2 somewhere..or something else? I don't see where.

3.62 seems about right to my eye: four one quart containers of milk fitted side by side in a square looks to be a little less than a cubic foot.
Last edited by rbgarr; 07-30-2012 at 03:45 PM. Reason: Doh. I found the mistake.

2. ## Re: Cubic foot to gallons conversion

Learn to work in metric. You know it makes sense.

Your plastic bucket measures 1.3 gallons imperial or 2 US gallon.

3. ## Re: Cubic foot to gallons conversion

Yup. The bucket is 2 gallons, not one, so it's all good now.

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## Re: Cubic foot to gallons conversion

Rbgarr,

Your constants and math look to be correct - IMHO, the error is because the bucket is not of constant diameter. I just made a vertical cylindrical toilet flush tank from a piece of 6" ID PVC sewer pipe, and with a flat bottom, 18" of fill calculates to 2.19 gallons. I bet if you put your gallon of water into such a pipe, the level will be a shade above 8.2".

Boat on using inches and gallons.

Joe

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## Re: Cubic foot to gallons conversion

I have 7.48 gallons per cubic feet written on my white board, so I hope that's right. If not then I will most likely get fired sooner or later.

Mickey Lake

6. ## Re: Cubic foot to gallons conversion

One gallon equals 231 cubic inches.

Brian

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## Re: Cubic foot to gallons conversion

. . . and 12 cubed is 1728, which divided by 231 is 7.480519480.... so you might be safe on that score Mickey.

8. ## Re: Cubic foot to gallons conversion

Originally Posted by bamamick
I have 7.48 gallons per cubic feet written on my white board, so I hope that's right. If not then I will most likely get fired sooner or later.

Mickey Lake
Thats the number most of us dumb a\$\$ engineer types use, so if you get fired for that Mickey you will be in plenty of company.

Cheers,

Bobby

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## Re: Cubic foot to gallons conversion

I love metric.

10. ## Re: Cubic foot to gallons conversion

Originally Posted by Phil Y
I love metric.
Yep.

cept for fish. metric fish never sound very good ones.

11. ## Re: Cubic foot to gallons conversion

An easier method of finding the volume of a cylinder is .785x diameter squared x height with all units in feet or decimals therof.

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## Re: Cubic foot to gallons conversion

I actually really like metric, as well. In Germany the units of measurement in the plant are all so uniform and simple. For instance, the storage tanks in our sister plant are 100 cubic metre tanks, and of course, since the scale on the level indicators is from 0-100%, it take you about 10 seconds to look and see what your inventory is at any given time. If a Euro-container holds 15 cubic metres then you lose 15% out of storage every time you fill a container. It is so simple.

Jimmy Carter was painted as the devil when he tried to get us to begin using the metric system back in the '70's. How much money would have been saved over the years by the US using a worldwide uniform system of measurement? A lot of money.

In our plant we use litres, grams, metric tonnes, and degrees Celsius every day. But we also use pounds and gallons. Our pressures are measured in millibars, millimeters of Mercury, inches of water column, psig and psia. It's a mess, really, but it's America. A melting pot hodge-podge. It's confusing, but I guess it works.

Mickey Lake

Mickey Lake

13. ## Re: Cubic foot to gallons conversion

Just go to Google or any other search engine and type in the conversion you want. DONE.

14. ## Re: Cubic foot to gallons conversion

Ok! Lets go metric, then I may ask, "How many cubic centimeters are there in a liter?"

15. ## Re: Cubic foot to gallons conversion

Originally Posted by stewart711
Ok! Lets go metric, then I may ask, "How many cubic centimeters are there in a liter?"
Is this a trick question? it's a 1000.

16. ## Re: Cubic foot to gallons conversion

When I go to a store in the USA I still buy a gallon of milk or a 1/2 gallon. I don't care how many liters it is.
When I buy a quart of oil I don't care how many liters it is.
When I measure a motorcycle part to be machined I still measure in .001 thousandths of an inch. So does the machinist.
When i buy something I still want the cost in DOLLARS.

This is still the USA bro@! Not france.

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## Re: Cubic foot to gallons conversion

Most of us know that a cubic foot of fresh water weighs 62.4 pounds (since we are interested in displacement volumes and weights),
and that "a pint's a pound." So 62.4 pints is 7.8 gallons.

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## Re: Cubic foot to gallons conversion

Originally Posted by donald branscom
...When i buy something I still want the cost in DOLLARS...
The USA was an early adopter of the principle of breaking things down by 10's and 100's, in that the USA was the first nation to adopt a dollar of 100 cents. Maybe this is where the French got the idea for the Metric System?

Tom

19. ## Re: Cubic foot to gallons conversion

Originally Posted by donald branscom
When I go to a store in the USA I still buy a gallon of milk or a 1/2 gallon. I don't care how many liters it is.
When I buy a quart of oil I don't care how many liters it is.
When I measure a motorcycle part to be machined I still measure in .001 thousandths of an inch. So does the machinist.
When i buy something I still want the cost in DOLLARS.

This is still the USA bro@! Not france.
Ummm ... not the rest of the world .

20. ## Re: Cubic foot to gallons conversion

Originally Posted by bamamick
I actually really like metric, as well. In Germany the units of measurement in the plant are all so uniform and simple. For instance, the storage tanks in our sister plant are 100 cubic metre tanks, and of course, since the scale on the level indicators is from 0-100%, it take you about 10 seconds to look and see what your inventory is at any given time. If a Euro-container holds 15 cubic metres then you lose 15% out of storage every time you fill a container. It is so simple.
Ditto here.

1 cc of water @4 deg C is 1 gram. 1000cc = 1 liter = 1000 grams = 1 kilogram.

The pint's a pound the world 'round, depending on which pound and who's pint...

Are we talking pounds avoirdupois, troy, Tower, Mercantile, London/Hansa, or one of the other flavors? Is it an imperial/ale pint or a US pint. If it's US, is it a liquid measure ( based on the wine gallon) or dry measure (based on the Winchester or corn gallon).

The liter's a kilo the world 'round...but I'll give you that it doesn't roll quite as trippingly off the tongue.

21. ## Re: Cubic foot to gallons conversion

Originally Posted by spirit
Most of us know that a cubic foot of fresh water weighs 62.4 pounds (since we are interested in displacement volumes and weights),
and that "a pint's a pound." So 62.4 pints is 7.8 gallons.
Sorry, as a career water/ wastewater type environmental guy, I gotta tell ya, it's 7.48 gals/ cu ft. That's indisputable in the US, and even worked for us in NZ. Turns out math is important after all.

22. ## Re: Cubic foot to gallons conversion

6.25 Imp gallons to the c ft IIRC. It's been a long time since we got away from gallons and cubic feet .
Last edited by PeterSibley; 08-12-2012 at 12:15 AM.

23. ## Re: Cubic foot to gallons conversion

Originally Posted by bamamick
I actually really like metric, as well. In Germany the units of measurement in the plant are all so uniform and simple. For instance, the storage tanks in our sister plant are 100 cubic metre tanks, and of course, since the scale on the level indicators is from 0-100%, it take you about 10 seconds to look and see what your inventory is at any given time. If a Euro-container holds 15 cubic metres then you lose 15% out of storage every time you fill a container. It is so simple.

Jimmy Carter was painted as the devil when he tried to get us to begin using the metric system back in the '70's. How much money would have been saved over the years by the US using a worldwide uniform system of measurement? A lot of money.

In our plant we use litres, grams, metric tonnes, and degrees Celsius every day. But we also use pounds and gallons. Our pressures are measured in millibars, millimeters of Mercury, inches of water column, psig and psia. It's a mess, really, but it's America. A melting pot hodge-podge. It's confusing, but I guess it works.

Mickey Lake

Mickey Lake
When I was in college studying engineering we used SI units. Took a bit, but you learned to think that way and metric is oh so much easier to work with. We had to do about 10% of our problems in "English" units, we would convert the givens to SI, do the work, then convert the answer back to "English". When the profs figured this out and made us show our work in "English" it sucked.

Then we got out in the real world where we use a bizare hodge-podge. In my last life I learned to think of product density in kg/gallon.

Cheers,

Bobby

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## Re: Cubic foot to gallons conversion

Well, I was born in '65, so I was raised metricated. I will say that I've grown to love feet & inches. They have a wonderful symetry and useable size. Like a window is 3 foot across and the framing is 1 inch etc, it makes it very easy to visualise and build. Metric is often too big or too small. This, BTW, was pointed out to me by a Swiss man!
I will ask this question here.
If I wish to float 1 metric tonne ( ie 1000 cm3) does a 100 x 100 x 100 cm box float it? I think the top of the box would be at water level. Is this so?
(not worried about wall thickness etc, just a more or less kind of understanding)
Thanks.

25. ## Re: Cubic foot to gallons conversion

Originally Posted by Jazzman
Well, I was born in '65, so I was raised metricated. I will say that I've grown to love feet & inches. They have a wonderful symetry and useable size. Like a window is 3 foot across and the framing is 1 inch etc, it makes it very easy to visualise and build. Metric is often too big or too small. This, BTW, was pointed out to me by a Swiss man!
I will ask this question here.
If I wish to float 1 metric tonne ( ie 1000 cm3) does a 100 x 100 x 100 cm box float it? I think the top of the box would be at water level. Is this so?
(not worried about wall thickness etc, just a more or less kind of understanding)
Thanks.
Yes exactly when in fresh water, with no freeboard. As sea water is more dense you would have 2.5mm freeboard in sea water.

26. ## Re: Cubic foot to gallons conversion

Originally Posted by Peerie Maa
Yes exactly when in fresh water, with no freeboard. As sea water is more dense you would have 2.5mm freeboard in sea water.
Sounds safe to me .

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## Re: Cubic foot to gallons conversion

Great! Thanks for that!

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