Four calculators, one panel.
Pick a mode below — switch species on or off, everything recalculates live as you type, and every result explains itself.
For a reaction aA + bB ⇌ cC + dD — switch B or D off if your reaction only has one reactant or product.
Enter current (not necessarily equilibrium) concentrations and a known Kc — the calculator finds Q and tells you which way the reaction still needs to shift.
Can be negative — e.g. N₂ + 3H₂ ⇌ 2NH₃ has Δn = 2 − (1+3) = −2.
Solves a simple A ⇌ B equilibrium (1:1 stoichiometry) from its ICE table.
Usually 0 if the reaction starts with pure A.
Two inputs to an answer.
No manual required — but here's the entire flow in four moves.
Pick a mode
Kc for a known equilibrium mixture. Q vs K to check whether a mixture is at equilibrium yet. Kp ⇌ Kc for gas-phase conversions. ICE table to solve a simple A ⇌ B system from scratch.
Enter what you know
Type coefficients and concentrations, switch a second reactant or product on or off with the checkboxes, or pick temperature units. The example chips fill everything in with one tap.
Read the results
The main answer sits up top in large type. Related values — the other species, the shift direction, or the second constant — sit below, and the exact formula with your numbers substituted sits at the bottom.
Trust the checks
Impossible inputs — a negative concentration, a zero denominator — get flagged with a plain-English reason instead of a wrong or broken answer. Copy any result set with one click.
Three ideas behind every mode.
One ratio, compared two ways, plus a temperature correction for gases.
Equilibrium constant
For aA + bB ⇌ cC + dD, using equilibrium concentrations. A large Kc favours products; a small Kc favours reactants.
Reaction quotient
Same expression, any point in time. Q < Kc shifts toward products; Q > Kc shifts toward reactants; Q = Kc means equilibrium.
Kp from Kc
R = 0.0821 L·atm/(mol·K), T in kelvin, and Δn is moles of gaseous product minus moles of gaseous reactant.
Questions people actually ask.
The short answers — with the long ones one tap away.
What is the equilibrium constant Kc?+
Kc is the ratio of product concentrations to reactant concentrations at equilibrium, each raised to its stoichiometric coefficient: Kc = [C]^c[D]^d ÷ ([A]^a[B]^b) for aA + bB ⇌ cC + dD. A large Kc means the equilibrium favours products; a small Kc means it favours reactants.
How do I calculate Kc from concentrations?+
Enter the stoichiometric coefficients and equilibrium concentrations in the Kc tab — switch a second reactant or product off if your reaction only has one of each. The calculator raises each concentration to its coefficient and divides products by reactants.
What is the reaction quotient Q, and how is it different from Kc?+
Q uses the same formula as Kc, but with concentrations at any point in time rather than only at equilibrium. Comparing Q to a known Kc tells you whether the system has reached equilibrium yet.
How do I know which way a reaction will shift?+
Enter current concentrations and a known Kc in the Q vs K tab. If Q < Kc, the reaction shifts toward products (forward). If Q > Kc, it shifts toward reactants (reverse). If Q = Kc, it's already at equilibrium.
What is the relationship between Kp and Kc?+
For gas-phase reactions, Kp = Kc(RT)^Δn, where R = 0.0821 L·atm/(mol·K), T is temperature in kelvin, and Δn is moles of gaseous product minus moles of gaseous reactant. The Kp ⇌ Kc tab converts either way.
How does an ICE table work?+
An ICE table tracks Initial, Change, and Equilibrium concentrations. For a simple A ⇌ B equilibrium, if A changes by -x then B changes by +x; substituting into Kc = [B]/[A] gives a solvable equation for x. The ICE table tab does this algebra and returns both equilibrium concentrations.
Is this tool free, and where does my data go?+
It's completely free and runs entirely in your browser — nothing you type is uploaded, logged, or sent to any server. No account, no sign-up, no limits.