Sugar syrup calculator 1:1 and 2:1 (weight vs volume)
Pick 1:1 or 2:1 and whether you measure by weight or by volume. Then enter how much syrup you want, or how much sugar you have. Dissolved sugar takes up room, so a gallon of water and a few pounds of sugar make more than a gallon of syrup. Measured sugar solution densities give the final volume and weight, and the table below shows how far apart the weight and volume recipes are.
By weight or by volume
Some guides say the choice hardly matters. The Foxhound Bee Company syrup math page says of weight and volume that it "doesn't matter because it has the same result". The numbers below show how far apart the two recipes are, so you can decide for yourself.
A 2:1 ratio means two parts sugar to one part water, and the parts can be weighed or measured in a cup. The two give different syrups, because a cup of granulated sugar weighs less than a cup of water: about 198 g by the King Arthur Baking weight chart, against about 236 g for a US cup of water.
So 2:1 by weight is 66.7% sugar, while 2:1 by volume is 62.6%. For 1:1 it is 50.0% by weight against 45.6% by volume. Sources use both: Mississippi State Extension (Publication 2941) gives heavy syrup as 16–17 lb of sugar per gallon of water, which is 2:1 by weight, and UF/IFAS (ENY-161) describes 2:1 by volume. Either way the bees get a thick syrup; weighing gives the same result every time.
One more difference is what the gallon is. Mississippi State's 16–17 lb is per gallon of water poured in: 16.7 lb of sugar for 2:1 by weight. The first row of the table above is per gallon of finished syrup, which is 7.38 lb of sugar, because the sugar adds volume. Both describe the same recipe. The University of Arizona figure of about 7 lb of stores per gallon of 2:1 syrup (az2014) is a gallon of finished syrup too.
One gallon and one liter of each syrup
| Recipe | 1 US gal of syrup | 1 L of syrup | Per gal of water |
|---|---|---|---|
| 2:1 by weight | 7.38 lb sugar 7.1 cups water |
880 g sugar 440 mL water |
16.7 lb sugar 2.00 kg per L |
| 2:1 by volume | 6.81 lb sugar 7.8 cups water |
820 g sugar 490 mL water |
14.0 lb sugar 1.67 kg per L |
| 1:1 by weight | 5.13 lb sugar 9.9 cups water |
610 g sugar 620 mL water |
8.3 lb sugar 1.00 kg per L |
| 1:1 by volume | 4.59 lb sugar 10.5 cups water |
550 g sugar 660 mL water |
7.0 lb sugar 0.84 kg per L |
A 25 lb bag of sugar made into 2:1 syrup by weight takes 1.50 US gallons of water and gives about 3.39 gallons of syrup.
Where the numbers come from
- Syrup density: the sucrose solution table in the National Bureau of Standards Letter Circular LC 770, true density at 20 °C by percent sucrose by weight, read between whole percents. For example 50% sugar is 1.22957 g/mL and 66% is 1.32242 g/mL.
- Water: 0.99823 g/mL at 20 °C, the 0% row of the same table. One US cup is 236.6 mL.
- Sugar by volume: 198 g per US cup of granulated sugar (King Arthur Baking). How tightly sugar packs into a cup varies, which is one more reason the by-weight numbers are steadier.
- Warm syrup is a little less dense than at 20 °C, so a hot batch measures slightly more until it cools.
Which ratio when
Cornell's overwintering guide says to feed 2:1 cane sugar syrup when a colony needs more weight for winter, and to skip 1:1 in the fall, because the bees have to evaporate the extra water and that gets harder as the days and nights cool. Mississippi State's Publication 2941 lists a thin, a medium and a heavy syrup with sugar per gallon of water for each.
To find out how much the colony needs, the winter honey stores calculator estimates what is in the hive now, and how much sugar to feed bees for winter turns the gap into pounds of sugar and gallons of 2:1.