To convert quarts to cups (qt to cup), multiply by 4. 1 quart equals 4 cup, about 1.3 times as much as a wine bottle.
| quarts | cups |
|---|---|
| 1 quart | 4 cup |
| 2 quarts | 8 cup |
| 5 quarts | 20 cup |
| 10 quarts | 40 cup |
| 25 quarts | 100 cup |
| 50 quarts | 200 cup |
| 100 quarts | 400 cup |
| 250 quarts | 1,000 cup |
| 500 quarts | 2,000 cup |
| 1000 quarts | 4,000 cup |
The factor is 4.00000, which is derived rather than defined, so any decimal you see has been rounded somewhere.
For mental arithmetic the factor is close enough to 4 to use directly: multiply quarts by 4 and the answer is right to within a rounding error.
The reverse factor is 0.25, so one cup is that many quarts. Two decimal places is plenty for most purposes, and three is more than a tape measure can justify.
To anchor the scale: 1 quart is about 4 cup.