They are both the same size.
Remember that 64 ounces is a half gallon, so 10 half gallons (640 ounces) is 5 whole gallons. Or, if you divide 128 (ounces in a gallon) into 640, you get 5.
In the US: 1pt = 16 fl oz 5 gallons = 5 x 8 x 16 = 640 fl oz both the same In the UK: 1pt = 20 fl oz 5 gallons = 5 x 8 x 20 = 800 fl oz 5 gallons is bigger than 640 fl oz.
One gallon has 4 quarts. Each quart has two pints, so that is a total of 8 pints per gallon. Each pint has 2 cups, so that is a total of 16 cups per gallon. Each cup has 8 fl. oz. so that is a total of 128 fl oz per gallon. Therefore, 5 gallons = 128*5 = 640 US fl. oz. UK 20 fl. oz to the pint. 160 fl.oz. to a gallon. Therefore, 5 gallons = 160x5 = 800 fl.oz. Imperial
128 fl oz = 1 gallon 2 x 128 fl oz = 256 fl oz = 2 gallons 4 x 128 fl oz = 512 fl oz = 4 gallons
640 Imperial fluid ounces = 4 Imperial gallons.
Assuming you mean 12.6 fl oz, I guess you're American (using the oz abbreviation for fl oz), thus: 1 gal = 128 fl oz → 5 gal = 5 × 128 fl = 640 fl oz → 640 fl oz ÷ 12.6 fl oz ≈ 50.79
1 gallon = 128 fl oz, 2 gallons = 256 fl. oz
265316.9 fl oz equals 1725.96 imperial gallons
2240 Imperial fl oz = 14 Imperial gallons.
That is 1,920 fl oz.
5 gallons x 128 oz/gallon = 640 oz of gas 640/32 = 20 oz of oil
640 ounces.
5 US gallons = 640 fluid ounces