How It Works
This calculator works in 4 steps.
Enter the molarity
Type the target in M, mM, or µM.
Enter the volume
Type the batch volume in L, mL, or µL.
Enter the molecular weight
Type the MW in g/mol.
Read the mass and balance check
The calculator returns g, mg, and µg and compares the mass with the minimum weighing value.
The Formula
The formula multiplies amount of substance by molecular weight.
n (mol) = M × V (L)m (g) = n × MWm ≥ m_min of the balance- n:
- Moles of reagent
- M:
- Molarity
- V:
- Volume
- MW:
- Molecular weight
- m_min:
- Smallest mass the balance weighs within tolerance
A 50 mL batch of 10 mM sodium citrate dihydrate (MW 294.18 g/mol) needs 0.010 × 0.050 × 294.18 = 0.1471 g (147.1 mg).
Conversion Table
The conversion table lists the mass in g and mg for 6 molarity, volume, and MW combinations.
| Molarity | Volume | MW | Mass (g) | Mass (mg) |
|---|---|---|---|---|
| 0.1 M | 100 mL | 58.44 g/mol | 0.5844 g | 584.4 mg |
| 0.01 M | 50 mL | 294.2 g/mol | 0.1471 g | 147.1 mg |
| 1 M | 10 mL | 74.55 g/mol | 0.7455 g | 745.5 mg |
| 0.05 M | 250 mL | 157.6 g/mol | 1.97 g | 1,970 mg |
| 0.002 M | 25 mL | 372.2 g/mol | 0.01861 g | 18.61 mg |
| 0.5 M | 1,000 mL | 40 g/mol | 20 g | 20,000 mg |
What Is the Solid Reagent Mass Calculator?
The Solid Reagent Mass Calculator is a tool that returns the mass of a dry reagent required for a solution of set molarity and volume, with output in g, mg, and µg. The calculator matches the result to the readability of the balance, such as 0.1 mg for an analytical balance.
Small batches often call for milligram amounts. A 25 mL batch of 2 mM EDTA disodium needs 18.6 mg, which sits close to the lower limit of many balances. The calculator flags amounts below the user's minimum weighing value and suggests a larger batch or a stock-and-dilute route.
Common Uses
There are 5 main uses of this calculator.
Small-batch preparation
Researchers weigh mg amounts for 10 to 50 mL batches.
Analytical standards
Analysts weigh primary standards such as potassium hydrogen phthalate (KHP).
Inhibitor solutions
Biochemists weigh protease inhibitors for fresh daily solutions.
Field test kits
Technicians pre-weigh reagent packets for field use.
Weighing SOPs
QA teams check that weighed amounts sit above the balance minimum.