Equilibrium Constant Calculator
Kp from Kc, with Δn counting gases only.
Work out Equilibrium Constant. Kp from Kc, with Δn counting gases only. Temperature in kelvin, handled for you.
Moles of gaseous product minus gaseous reactant. Solids and liquids do not count.
Kp
1
Kc 1 · Δn 0 · favours neither
Kp = Kc(RT)^Δn, with R as 0.08206 L·atm/(mol·K) because equilibrium constants are conventionally written with pressures in atmospheres. When Δn is zero the two are numerically equal and the units cancel. Only gases count in Δn — pure solids and liquids are omitted from equilibrium expressions entirely, since their concentrations do not change.
How the Equilibrium Constant Calculator works
Kp = Kc(RT)^Δn, with R as 0.08206 L·atm/(mol·K) because equilibrium constants are conventionally written with pressures in atmospheres. Only gases count in Δn — pure solids and liquids are omitted from equilibrium expressions entirely.
Also known as: kc to kp calculator · kp kc conversion · equilibrium constant formula · how to calculate kp
Frequently asked questions
How do I convert Kc to Kp?
Kp = Kc(RT)^Δn, where Δn is moles of gaseous product minus gaseous reactant. When Δn is zero the two are numerically equal.
Why are solids and liquids left out?
Because their concentrations do not change as the reaction proceeds — a pure solid has a fixed density. Including them would put a constant inside a constant.
What does the size of K tell me?
Where the equilibrium sits. K above 1 favours products, below 1 favours reactants. It says nothing about how fast equilibrium is reached.
Put this calculator on your own site
Free to use, on any site, commercial or not. Paste this where you want it to appear. It is a plain iframe, so it works in WordPress, Squarespace, Wix, Webflow, Ghost and anything else that accepts HTML.
<iframe src="https://www.thecalclibrary.com/embed/equilibrium-constant-calculator" width="100%" height="640" style="border:1px solid #e2e8f0;border-radius:12px" loading="lazy" title="Equilibrium Constant Calculator"></iframe>
<p style="font:13px/1.5 system-ui,sans-serif;margin:6px 0 0;color:#64748b">Powered by <a href="https://www.thecalclibrary.com/equilibrium-constant-calculator" style="color:#64748b">Equilibrium Constant Calculator</a> from The Calc Library</p>The only condition is that the credit line below the frame stays in place. That one line is what pays for the tool being free — it is how anyone else finds it.
Related calculators
Gibbs Free Energy Calculator
ΔG = ΔH − TΔS, with the unit mismatch handled.
OpenArrhenius Equation Calculator
Rate constants, and where the 'doubles per 10 degrees' rule comes from.
OpenNernst Equation Calculator
Cell potential away from standard conditions, plus ΔG and K.
Open