643 milliliters in US quarts
Result
The conversion result is: 643 milliliters is equivalent to 0.679450518665158 US quarts.[1]
Conversion formula
How to convert 643 milliliters to US quarts?
We know (by definition) that: 1 ml ≈ 0.00105668820943259 usquart.
We can set up a proportion to solve for the number of US quarts.
1 ml / 643 ml ≈ 0.00105668820943259 usquart / x usquart
Now, we cross multiply to solve for our unknown x:
x usquart ≈ (643 ml / 1 ml) * 0.00105668820943259 usquart → x usquart ≈ 0.6794505186651554 usquart
Conclusion:
643 ml ≈ 0.6794505186651554 usquart

Conversion in the opposite direction
The inverse of the conversion factor is that 1 US quart is equal to 1.47177752099533 times 643 milliliters.
It can also be expressed as: 643 milliliters is equal to 1 / 1.47177752099533 US quarts.
Approximation
An approximate numerical result would be: six hundred and forty-three milliliters is about zero point six eight US quarts, or alternatively, a US quart is about one point four seven times six hundred and forty-three milliliters.
Footnotes
[1] The precision is 15 significant digits (fourteen digits to the right of the decimal point).
Results may contain small errors due to the use of floating point arithmetic.