Live Demo

Enter a chemical equation and choose the output format to see the balanced result.

Output formatTextHTMLLaTeX

Show coefficient of 1

Chemical equation

H2 + O2 -> H2O

Use -> to separate reactants and products. Charges: Fe2+, SO4^2-. Groups: Ca3(PO4)2.

The demo runs the modern build; the ES3 legacy build (fast-balance/legacy) returns identical equations for every input — see Installation.

How it works

• Type or paste an unbalanced equation; the result updates as you type.
• Choose the output format: plain text, HTML, or LaTeX.
• Toggle "Show coefficient of 1" to control unit coefficient display.
• Spectator species (a species on both sides) are balanced, not rejected.
• Genuinely underdetermined systems return the minimal balance and set underdetermined: true.
• Invalid or unbalanceable input shows a clear error message.

Supported notation

Notation	Example	Description
Arrows	->, →, ⇌, <=>, =, -->	Separates reactants and products
Conditions	--Δ-->, ->[cat]	Ignored
Ionic charges	Fe2+, SO4^2-, Fe^{3+}, Fe+2	Several charge spellings
Complex charge	[Fe(CN)6]4-	Digits after ] are the charge
Electrons	e, e-, e+	Redox half-reactions
Parentheses	Ca3(PO4)2	Groups atoms with a subscript
Hydrates	CuSO4·5H2O	·, •, * separators
State symbols	(s), (l), (g), (aq)	Stripped during parsing
Unicode	H₂O, Fe²⁺	Normalized automatically
Isotopes	^238U, C-14	Used by nuclear mode
Groups	Ph, Me, Et, tBu	Expanded to atoms
Abbreviations	NADP, NADPH, ATP	Expanded to atoms
Particles	hv, hν, Δ, n, p	Photon/heat/nucleon tokens
Placeholders	R, M, X, Q, Z	Generic group/metal/halogen

Example equations

Simple reactions

• H2 + O2 -> H2O
• Fe + O2 -> Fe2O3
• N2 + H2 -> NH3

Combustion

• CH4 + O2 -> CO2 + H2O
• C3H8 + O2 + N2 -> CO2 + H2O + N2 (air, with N2 spectator)

Redox

• MnO4- + H+ + e- -> Mn2+ + H2O
• Cr2O7^2- + H+ + e- -> Cr3+ + H2O
• Fe2+ + MnO4- + H+ -> Fe3+ + Mn2+ + H2O

Ionic

• Ag+ + Cl- -> AgCl
• Ba2+ + SO4^2- -> BaSO4
• [Cu(NH3)4]2+ + Cl- -> [Cu(NH3)4]Cl2

Underdetermined

• C + O2 -> CO + CO2

Unicode

• H₂ + O₂ -> H₂O
• Fe²⁺ + Cl⁻ -> FeCl₂

Complex

• Ca3(PO4)2 + SiO2 + C -> CaSiO3 + P4 + CO
• K4Fe(CN)6 + KMnO4 + H2SO4 -> KHSO4 + Fe2(SO4)3 + MnSO4 + HNO3 + CO2 + H2O