Science Calculators

Chemistry and physics calculations are unit bookkeeping as much as arithmetic. Moles, molarity, concentration, gas volumes and reaction yields all depend on tracking what each quantity is measured in, and most errors are a factor of 1,000 from a milli- prefix rather than a mistake in the formula. These calculators keep the units visible at every step.

The mole is the pivot. It connects mass to particle count through molar mass, and particle count to Avogadro's number, which is why so many of these tools convert into or out of moles rather than directly between the quantities you started with. Molarity extends the same idea to solutions as moles per litre, and dilution problems are then just conservation: the moles of solute before and after adding water are identical, which is what M₁V₁ = M₂V₂ is saying.

Concentration has more units than any other quantity here, and they are not interchangeable across contexts. Percent by volume, percent by mass, ppm, ppb and molarity all describe strength, but converting between them needs a density or a molar mass. For dilute aqueous solutions, one ppm is very nearly one milligram per litre — a shortcut worth knowing and worth not applying to gases or solids.