Chemistry calculators
The arithmetic that sits between a balanced equation and a flask. Each one works in the page, shows its formula and a worked example, and says where the calculation stops being exact.
Molar mass calculator
Enter a formula and get its molar mass, broken down by element.
Molarity calculator
Relate concentration, volume and moles. Leave the unknown blank.
Dilution calculator (C₁V₁ = C₂V₂)
C₁V₁ = C₂V₂. Leave the unknown blank.
Percent yield calculator
Actual over theoretical, as a percentage. Leave the unknown blank.
Beer–Lambert law calculator
A = εlc. Leave the unknown blank.
pH, pOH and [H⁺] calculator
Convert between pH, pOH, [H⁺] and [OH⁻]. Leave the unknown blank.
Buffer pH calculator (Henderson–Hasselbalch)
pH = pKa + log([A⁻]/[HA]). Leave the unknown blank.
Chemical equation balancer
Type an equation with an arrow; get the smallest whole-number coefficients.
Theoretical yield and limiting reagent calculator
Enter the balanced equation's reactants and masses; get the limiting reagent and the theoretical yield.
Empirical formula calculator
Enter each element and its percentage by mass; get the simplest whole-number formula.
Why these and not fifty
A calculator is worth a page when it has one right answer and somebody would otherwise do it on paper. That rules out most of what gets published as a chemistry tool: a page that multiplies two numbers and surrounds them with keywords helps nobody, and a tool that dresses up a guess as a result is worse.
Each of these states its assumptions, because most are exact only inside a range. The Beer–Lambert law is linear in dilute solution and not otherwise; Henderson–Hasselbalch assumes what you mixed is what is at equilibrium; pH + pOH = 14 is true at 25 °C and nowhere else. Those limits are on the pages rather than in a footnote, because that is where somebody reading an answer will be looking.
If you need to know what a reaction gives rather than how much of it, prediction is a different question and lives in the workstation.