Solution Preparation Calculator | Weigh, Mix & Prepare Any Solution
The practical lab tool for preparing solutions from solid compounds. Enter your target concentration, volume, and compound's molar mass the calculator tells you exactly how many grams to weigh. Also solves dilutions, back-calculates molar mass, and finds concentration from mass and volume. Free, no login, works offline.
Solve for any variable: M = n ÷ V. Enter two known values and select what to calculate. For calculating grams to weigh, use the Mass tab.
mol/L
mol
Volume of solution
Mass (g) needed per volume at each concentration. Source: NIST WebBook molar masses.
| Compound | 0.1 M 100 mL | 0.5 M 500 mL | 1 M 1 L |
|---|---|---|---|
| NaCl | 0.58 | 14.61 | 58.44 |
| NaOH | 0.40 | 10.00 | 40.00 |
| KCl | 0.75 | 18.64 | 74.55 |
| KH₂PO₄ | 1.36 | 34.02 | 136.09 |
| Na₂HPO₄ | 1.42 | 35.49 | 141.96 |
| Glucose | 1.80 | 45.04 | 180.16 |
| Urea | 0.60 | 15.02 | 60.06 |
| EDTA | 2.92 | 73.06 | 292.24 |
All values in grams. Molar masses from NIST WebBook.
Volume
1 L = 1000 mL = 1,000,000 µL
1 mL = 0.001 L = 1000 µL
Mass
1 kg = 1000 g = 1,000,000 mg
1 g = 0.001 kg = 1000 mg
Concentration
1 M = 1000 mM = 1,000,000 µM
1 mM = 0.001 M = 1000 µM
Always add acid to water, not water to acid prevents violent exothermic splashing
NaOH dissolving is highly exothermic dissolve slowly in an ice bath for concentrated solutions
Use PPE: lab coat, nitrile gloves, safety goggles before handling any reagent
Allow solution to reach room temperature before diluting to the volumetric mark
Label every container with compound, concentration, date, and preparer (per OSHA 29 CFR 1910.1200)
Dispose of waste according to your institution's chemical waste protocol
Preparing a chemical solution always starts at the analytical balance, not the volumetric flask. The entire workflow weigh solid, dissolve, dilute to mark depends on calculating the right mass first. Our solution preparation calculator automates that first step so the rest of the process is straightforward and reproducible.
Solute: What You Weigh
- ✓The substance being dissolved the ingredient you measure on a balance
- ✓Usually present in the smaller amount (e.g. 5.84 g NaCl per liter)
- ✓Can be a solid (NaCl, glucose), liquid (acetic acid), or gas (CO₂ dissolved)
- ✓Examples: sodium chloride, potassium phosphate, urea, EDTA
Solvent: What You Dilute Into
- ✓The dissolving medium usually Type I or Type II water in the lab
- ✓Present in the larger quantity (most of your final volume)
- ✓Water is universal: aqueous solutions dominate biology and analytical chemistry
- ✓Organic solvents (ethanol, DMSO, acetone) used for non-polar compounds
Why Getting the Mass Right Matters More Than Anything
Every downstream error in solution chemistry traces back to an incorrect mass. A 1% error in weighing NaCl for a 0.154 M saline solution means every cell culture, electrolyte assay, or osmolarity measurement built on that solution inherits that error. Accurate concentration is the foundation of:
Correct reactant ratios and predictable yields
Osmolarity and ion balance for cell viability
Drug concentration accuracy for dosing
Reproducing lab results at industrial volumes
Students learn the mass→moles→volume chain
Correct concentration prevents hazardous reactions
This is the most common solution preparation task in any lab: you have a jar of white powder (NaCl, NaOH, KH₂PO₄, glucose) and a target concentration. Here is the complete, USP-compliant procedure. Steps 1–2 are where this calculator is essential.
Calculate the required mass
Use the Mass tab above. Enter target molarity (M), target volume (mL), and molar mass (g/mol) of your compound. The calculator outputs: mass (g) = M × V × MM. Write this number down before touching anything.
Weigh on a calibrated analytical balance
Tare a clean, dry weighing boat or beaker. Add compound slowly until the balance reads your target mass ±0.001 g. For hygroscopic compounds (NaOH, CaCl₂, EDTA), work quickly they absorb moisture from the air, which inflates the mass and lowers your actual molarity. Record exact mass weighed, not the calculated target.
Dissolve in partial solvent volume
Transfer weighed solid to a beaker. Add approximately 60–70% of your target volume of solvent (usually distilled or Type II water). Stir with a magnetic stir bar until fully dissolved. For exothermic dissolutions (NaOH, H₂SO₄ additions), use an ice bath and add slowly.
Transfer to a calibrated volumetric flask
Pour the solution quantitatively into a Class A volumetric flask of the correct size. Rinse the beaker 2–3 times with small volumes of solvent and add all rinsings to the flask. This ensures no solute is left behind.
Dilute to the calibration mark
Add solvent slowly until the meniscus is at the calibration line. Read the meniscus at eye level with the mark parallax error is the most common volumetric mistake. For final drop-wise additions, use a Pasteur pipette. ISO 1042 Class A flasks have ±0.05 mL tolerance at 100 mL.
Mix and label
Invert the sealed flask 10–15 times to ensure homogeneity. Label immediately: compound name, concentration (M), solvent, preparation date, expiry date, preparer initials, hazard information. Per OSHA 29 CFR 1910.1200, every container must be labeled before leaving your hands.
⚠ Common Preparation Errors and How to Avoid Them
✗ Using molar mass from the wrong hydrate form
✓ CuSO₄ = 159.61 g/mol but CuSO₄·5H₂O = 249.68 g/mol always check the reagent bottle label. Use our Molar Mass Calculator for hydrates.
✗ Reading the meniscus from the wrong angle
✓ Always read from the bottom of the meniscus at eye level. Reading from above gives a low reading; from below gives a high reading both introduce concentration error.
✗ Diluting to mark before the solution cools
✓ Exothermic dissolutions contract on cooling you will be below the mark. Cool to room temperature first, then top up to the calibration line.
✗ Assuming 'reagent grade' means 100% pure
✓ Check the assay % on the certificate of analysis. If NaOH is 97% assay, divide target mass by 0.97 to get the correct weighing amount.
This calculator combines three related but distinct workflows into one place. Understanding which mode to use for your task will save you time and prevent errors.
Workflow 1: Prepare from Solid (Mass Tab)
This is the most common lab workflow. You want to make a solution and need to know how many grams to weigh. The two-step formula chain:
n = mass ÷ MM
Convert grams → moles
V = n ÷ M
Convert moles → volume
Combined: mass = M × V × MM
Solve directly for grams to weigh
Also solves for: Volume (how much solution can I make from this mass?), Concentration (what molarity did I achieve?), Molar mass (back-solve for unknown compound).
Workflow 2: Moles ↔ Volume ↔ Molarity (Molarity Tab)
Use this when you already know your moles for example, when adding a liquid reagent of known molarity, or working through a stoichiometry calculation.
M = n ÷ V
Rearranges to: V = n ÷ M (volume from moles) and n = M × V (moles in a given volume). For a full explanation of molarity and concentration comparisons (molarity vs molality vs normality), see our Molarity Calculator →
Workflow 3: Dilute a Stock Solution (Dilution Tab)
Once you have a stock solution, use C₁V₁ = C₂V₂ to find how much stock to pipette into your final volume. This tab solves for any one of the four variables.
C₁V₁ = C₂V₂
For serial dilutions, dilution factor mode, and per-step pipetting tables, use our dedicated Dilution Calculator → which supports those advanced modes.
Whether you need to weigh out grams for a 1 M stock, verify the concentration of a solution you already made, or quickly check how much stock to pipette our solution preparation calculator handles all three in one place.
Free · No Login · Works Offline · Lab-Accurate (IEEE 754) · Privacy-First