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Um..... - oldbloke's mutterings
September 8th, 2011
12:49 am
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Um.....
A gallon is 160 fl oz
1 fl oz of water weighs 1 oz
A pound is 16 oz
So, 1pound:1gallon is a 1:10 ratio

A litre is 1000 ml
1 ml of water weighs 1 g
So, 100g:1litre is a 1:10 ratio

Same

So why, if you ask Google "gallon litre" and "pound gram" do you not get the same number (shifted by a couple of decimals)
?????

(18 comments | Leave a comment)

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(Deleted comment)
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From:mhoulden
Date:September 8th, 2011 12:23 am (UTC)
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1 US pint = about 470 ml. I blame the temperance movement.
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From:offensive_mango
Date:September 8th, 2011 08:27 am (UTC)
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1 US pint = 2 US cups = 16 fl oz.
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From:offensive_mango
Date:September 8th, 2011 08:30 am (UTC)
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(then 2 pints (32 fl oz) in a US quart, and 4 quarts (128 fl oz) in a US gallon, if you're wondering how we get there)
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From:offensive_mango
Date:September 8th, 2011 08:27 am (UTC)
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Yup.
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From:oldbloke
Date:September 8th, 2011 09:24 am (UTC)
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Presumably because I use google.co.uk, it assumed the UK gallon. It was a fraction of a % off, not the 20% that the US gallon would give.
(Deleted comment)
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From:oldbloke
Date:September 8th, 2011 07:22 pm (UTC)
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yebbut if it had been 20% off it would have been obvious what had happened and I'd not have posted at all. Obviously one expects a man of your abilities to realise this!
I'm re-reading my Holmes collection, btw
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From:drdoug
Date:September 8th, 2011 06:51 am (UTC)
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It works if you say "Imperial gallon litre" or "UK gallon litre".
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From:oldbloke
Date:September 8th, 2011 09:30 am (UTC)
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In my Google.co.uk, I get:
"pound gram" -> 1 pound = 453.59237 grams
"UK gallon litre" -> 1 Imperial gallon = 4.54609188 litres

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From:bellinghman
Date:September 8th, 2011 09:08 am (UTC)
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Google is US.

The US saying is 'A pint's a pound the whole world 'round"'.

The UK saying is "A pint of water weighs a pound and a quarter'.

The first is just so wrong, not because of the units factor (the US fluid ounce is a different size too, just to throw the figures off further), but because it so strongly asserts that it applies everywhere.

You need to be strongly aware of this when using recipes that come from the US.
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From:oldbloke
Date:September 8th, 2011 09:25 am (UTC)
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No, it wasn't the 20% difference the US gallon would give, it was a tiny fraction.
Having read about it on Wiki, I can see why the USA ended up with a gallon that size, though.

Edited at 2011-09-08 09:26 am (UTC)
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From:bellinghman
Date:September 8th, 2011 09:33 am (UTC)
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Ah, an Imperial fluid ounce of water doesn't weigh the same as an avoirdupois ounce.

Avoirdupois ounce -> 28.3495231 grammes
Fluid ounce -> 28.4130625 millilitres

I'll leave you to check that that does indeed account for the difference you mention above.
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From:oldbloke
Date:September 8th, 2011 10:41 am (UTC)
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I would, but Wiki tells me a ml isn't really a gram anymore, and the extra arithmetic is off-putting
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From:blackberry44
Date:September 8th, 2011 10:01 am (UTC)
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I'm so thick I don't even understand the question.
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From:oldbloke
Date:September 8th, 2011 10:11 am (UTC)
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A gallon weighs 10lbs (a pint of water weighs a pound and a quarter)
A litre weighs 1kg (as we were taught at school)
So gallon/lb should be 10, and litre/gram should be 1000
So the imperial to metric conversion factors for weight and volume should be the same, just shifted a couple of decimal places.
But they're not, according to Google's calculator.

Turns out they changed the definition of the litre back in the 60s. And there may be an avoirdupois vs mumble thing going on on our side, too.
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From:blackberry44
Date:September 8th, 2011 10:24 am (UTC)
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Thanks for explaining. I think I understand now.
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From:bellinghman
Date:September 8th, 2011 04:14 pm (UTC)
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It's the avoirdupois/fluid ounce thing that's really having the effect:

fluid oz/oz:
100 * 28.3495231/28.4130625 = 99.7763725

(grammes per pound) / (litres per gallon):
453.59237/4.54609188 = 99.7763314

The ratio of these two values:
1:1.000000412

This is less than one part per million away from a true 1:1 ratio, and at least some of that may be due to rounding errors. The oz/oz ratio is a couple of parts per thousand away from unity.
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