To prepare a solution of glucose you need the grams, and grams is molarity × volume in litres × 180.156 g/mol. A litre of 1 M takes 180.156 g; 500 mL of 0.1 M takes 9.0078 g; 250 mL of 0.01 M takes 450.39 mg. Enter the strength you want and the volume you want it in, and the calculator returns the mass to weigh together with the same figure in milligrams and as a percentage strength.
The figure comes from the formula. Glucose is 6 × 12.011 (C) + 12 × 1.008 (H) + 6 × 15.999 (O), which is 180.156 g/mol, taking standard atomic weights, and every page here computes that sum rather than quoting it. Oxygen makes up the largest share of the mass: 6 of the 24 atoms in a formula unit are oxygen, and they account for 95.994 g of the 180.156 g, or 53.28% by mass. The derivation table below breaks the whole molecule down element by element.
Order of operations matters more than precision here. Dissolve the solid in rather less than the final volume, then make up to the mark once it has all gone into solution and come back to room temperature — warm solutions read low when they cool. If the calculated mass is under about 20 mg, prepare ten times the strength and dilute it tenfold by pipette instead, because C₁V₁ = C₂V₂ carries less error than a marginal weighing.
Blood sugar, dextrose in the kitchen and the standard carbon source in microbiology. Labs report it in mg/dL in the US and mmol/L elsewhere. At 180.156 g/mol it is heavier than 15 of the 21 organic compounds covered here, and that ranking matters more than it looks: uric acid has a molar mass of 168.112 g/mol, so a gram of it contains 7.16% more formula units than a gram of glucose. Weigh by mass and you are not weighing equal amounts of substance.
Two practical things move the result. Purity below 100% means the weighed mass overstates how much compound you have — at 98% assay, 3.6031 g of every 180.156 g is not the compound — and any water picked up from the air does the same. Both are systematic, so they shift every solution made from that jar in the same direction.
The formula
c- The molarity you want, in mol/L
V- The volume you want to make, in millilitres
180.156- The molar mass of glucose in g/mol, derived from its formula
m- The mass of glucose to weigh out, in grams
How it works, step by step
- Enter the molarity you want, in mol/L.
- Enter the volume you want to make, in millilitres.
- The two are multiplied together and by 180.156 g/mol.
- The result is the mass to weigh; dissolve it in part of the volume and then make up to the mark.
Worked examples
250 mL of 0.1 M glucose
Weigh 4.5039 g. That is 0.1 M × 0.25 L × 180.156 g/mol, and it comes to 4503.9 mg if your balance is set to milligrams. Dissolve in about 175 mL first, then make up to 250 mL.
500 mL of 0.5 M glucose
Weigh 45.039 g. That is 0.5 M × 0.5 L × 180.156 g/mol, and it comes to 45,039 mg if your balance is set to milligrams. Dissolve in about 350 mL first, then make up to 500 mL.
1000 mL of 1 M glucose
Weigh 180.156 g. That is 1 M × 1 L × 180.156 g/mol, and it comes to 180,156 mg if your balance is set to milligrams. Dissolve in about 700 mL first, then make up to 1000 mL.
How to read your score
Frequently asked questions
What is the molar mass of glucose (C6H12O6)?
It is 180.156 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 6 × 12.011 (C) + 12 × 1.008 (H) + 6 × 15.999 (O). One mole of glucose therefore weighs 180.156 g, and a gram of it is 5.5507 mmol.
What percentage of glucose is oxygen?
53.28% by mass. Each formula unit contains 6 oxygen atoms contributing 95.994 g of the 180.156 g total, so 100 g of glucose contains 53.28 g of oxygen and a kilogram contains 532.84 g of it.
How much glucose do I need for 1 litre of 1 M solution?
180.156 g — the molar mass in grams, which is what a 1 molar solution means. For 1 L of 0.1 M it is 18.0156 g, and for 1 L of 0.01 M it is 1.80156 g.
How much for 100 mL of 0.1 M?
1.80156 g. The volume is a tenth of a litre and the strength a tenth of molar, so the mass is a hundredth of 180.156 g. In milligrams that is 1801.56 mg.
Do I dissolve the solid first or make up the volume first?
Dissolve first, in perhaps 70% of the final volume, then make up to the mark. Adding solid to a full flask overshoots the volume and leaves the solution weak, and undissolved solid at the mark means the strength keeps changing as it goes in.
Can I dilute a stock solution instead of weighing?
Yes, and it is more accurate for small amounts. C₁V₁ = C₂V₂: to get 500 mL of 0.01 M from a 0.5 M stock, take 10 mL of stock and make up to 500 mL. Weighing the 900.78 mg that 500 mL of 0.01 M needs directly is the harder of the two.
Solution recipes for glucose
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Oxygen (O) | 6 | 15.999 | 95.994 | 53.28% |
| Carbon (C) | 6 | 12.011 | 72.066 | 40% |
| Hydrogen (H) | 12 | 1.008 | 12.096 | 6.714% |
| Total — one mole of glucose | 180.156 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 180.156 g/mol.
| Target | for 100 mL | for 250 mL | for 500 mL | for 1 L |
|---|---|---|---|---|
| 0.001 M | 18.0156 mg | 45.039 mg | 90.078 mg | 180.156 mg |
| 0.005 M | 90.078 mg | 225.195 mg | 450.39 mg | 900.78 mg |
| 0.01 M | 180.156 mg | 450.39 mg | 900.78 mg | 1.80156 g |
| 0.05 M | 900.78 mg | 2.25195 g | 4.5039 g | 9.0078 g |
| 0.1 M | 1.80156 g | 4.5039 g | 9.0078 g | 18.0156 g |
| 0.15 M | 2.70234 g | 6.75585 g | 13.5117 g | 27.0234 g |
| 0.2 M | 3.60312 g | 9.0078 g | 18.0156 g | 36.0312 g |
| 0.25 M | 4.5039 g | 11.2598 g | 22.5195 g | 45.039 g |
| 0.5 M | 9.0078 g | 22.5195 g | 45.039 g | 90.078 g |
| 1 M | 18.0156 g | 45.039 g | 90.078 g | 180.156 g |
| 2 M | 36.0312 g | 90.078 g | 180.156 g | 360.312 g |
Each cell is molarity × volume in litres × 180.156 g/mol. Dissolve the solid first and then make up to the marked volume — adding solid to a full volume overshoots it.
| Compound | Formula | Molar mass (g/mol) | Millimoles in 1 g |
|---|---|---|---|
| Tris base | C4H11NO3 | 121.136 | 8.2552 |
| Paracetamol | C8H9NO2 | 151.165 | 6.6153 |
| Uric acid | C5H4N4O3 | 168.112 | 5.9484 |
| Glucose (this page) | C6H12O6 | 180.156 | 5.5507 |
| Aspirin | C9H8O4 | 180.159 | 5.5507 |
| Caffeine | C8H10N4O2 | 194.194 | 5.1495 |
| EDTA | C10H16N2O8 | 292.244 | 3.4218 |
Ordered by molar mass. The last column is 1000/M, which is the number a weighed gram actually gives you.