Solution Concentration Calculator
The unit bridge: grams per litre on the bottle, moles per litre in the protocol, mg/mL on the pipette — one solution, every accent.
Solution Concentration Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Mass-based accents — no density or temperature correction
- Molar bridge needs the solute’s molecular weight
In short: 9 g of NaCl made to 1 L: 9.000000 g/L — which is also 9.000000 mg/mL, because g/L and mg/mL carry the same digits. Against MW 58.44 the molar bridge reads 9 / 58.44 = 0.154004 mol/L, and as percent w/v the same bottle is 0.900000% — the clinical saline bottle, priced in every accent at once.
Formula
g/L = m/V · mg/mL = g/L · mol/L = (g/L)/MW · % w/v = g/L / 10
Mass concentration is the most direct accent: what you weighed, per what you made. The other accents are unit changes on the same fact — mg/mL shares its digits with g/L, molarity divides by the molecular weight, and percent w/v is just g/L wearing clinical clothes (divide by ten).
Worked Example
- Enter the mass dissolved, in grams.
- Enter the solution volume, in litres.
- Enter the molecular weight for the molar bridge.
- Read the concentration in all its accents.
Defaults: 9 g NaCl to 1 L → 9.000000 g/L = 9.000000 mg/mL = 0.154004 mol/L = 0.900000% w/v.
Strengths & Limits Of This Model
Where this engine is strong
- All accents from one entry
- The g/L = mg/mL identity made explicit
Where it stops
- No w/w without density
- No osmotic accounting
Practical Use Cases
Reading bottle labels
g/L in, protocol units out
Protocol translation
between lab dialects
QC checks
one solution, four ledgers
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Solution Concentration Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
Why does mg/mL have the same digits as g/L?
Because the two conversions cancel: a gram is a thousand milligrams and a litre is a thousand millilitres, so dividing and multiplying by a thousand leaves the number untouched. 9 g/L is 9 mg/mL. Once seen, this saves a thousand slippery conversions a year — it is the quietest joke in the metric system.
How do I read a 0.9% saline bottle in molar terms?
Percent w/v is grams per 100 mL, so 0.9% is 9 g/L; divide by the molecular weight 58.44 to get 0.154004 mol/L. The bottle speaks weigh-and-see, the physiology paper speaks moles, and this page translates because both are describing one and the same bottle.
Which accent should a recipe use?
The one that maps to what you measure: grams on a balance for mass concentration, moles for chemistry that reacts, osmoles for cells that swell. Recipes written in one accent executed in another are a classic source of thousand-fold errors — the fix is to convert deliberately, on paper, once.
Is mass concentration okay for chemistry, or must I use molar?
For bookkeeping and dosing by weight, mass concentration is honest and sufficient. The moment a reaction or a receptor counts PARTICLES, molar is the truth — 9 g/L of glucose and 9 g/L of NaCl are the same mass accent but wildly different particle counts (0.049957 vs 0.154004 mol/L).
What is the difference between % w/v and % w/w here?
Percent w/v is grams per 100 mL of FINISHED solution — the clinical default, and what this page’s percent bridge prints. Percent w/w is grams per 100 g of solution, which needs densities to cross from volumes. Solids dissolved in liquids almost always mean w/v; read the label’s fine print.
Why do protocols quote mM instead of mol/L?
Because bench concentrations land in the millimolar range — 154 mM saline, 5 mM glucose — and small honest numbers beat fractional ones. The arithmetic is a prefix change, nothing more: 0.154004 mol/L is 154.004 mM, and the molarity page’s mmol identity makes the flask agree.
My bottle says mg/dL — is that here too?
It is the clinical accent: decilitres are a tenth of a litre, so mg/dL is tenfold mg/L. A glucose of 90 mg/dL is 900 mg/L = 0.9 g/L; divide by 180.156 for about 0.004996 mol/L (5 mM, the fastic standard). Different accent, same sentence.
How does percent w/v tie back to the percent page?
The percent bridge prints g/L divided by ten, which is exactly grams per 100 mL — the percent-solution page’s home turf. The two pages agree to the digit on the saline bottle: 9 g/L is 0.900000% w/v, and the mg/mL accent is ten times the percent figure in the other direction.