Battery chemical symbols (Pb, Cd, Hg)
The chemical symbols Hg, Cd or Pb printed beneath the crossed-out bin on a battery. They show that it contains more than a set amount of mercury, cadmium or lead.
How to read it
Under the EU Batteries Directive, a battery containing more than 0.0005% mercury, 0.002% cadmium or 0.004% lead is marked with the chemical symbol for that metal: Hg, Cd or Pb. The symbol is printed beneath the crossed-out wheeled bin and covers at least a quarter of the bin’s size.
Also searched as: Cd symbol, Hg symbol, Pb symbol.
Differences by country or standard
The UK’s battery regulations set the same limits, by weight, but word the mercury rule for button cells: a button cell with more than 0.0005% mercury is marked Hg.
What the letters don’t tell you
NetRegs, the environmental guidance service for businesses in Scotland and Northern Ireland, says the chemical symbol shows that one of the restricted metals is in the battery, not how much of it. Lead isn’t restricted in batteries at all, it adds: Pb only marks a battery with more than 0.004% lead by weight.
Read next
- Next in Recycling symbolsBattery polarity marks (+ and −)The plus and minus signs on a battery, marking its positive and negative ends. Devices use the same signs to show which way round a battery goes.
- The same shape in Greek lettersQuantum circuit gate symbols (H, X, CNOT, measurement)The symbols of a quantum circuit diagram: each horizontal line is a qubit, a box with a letter is a gate (H for Hadamard, X, Y, Z, S, T), a dot joined by a line to ⊕ is a controlled-NOT, and a box with a meter is a measurement.
More recycling symbols
The same shape elsewhere
Browse symbols drawn with crosses or letters and numbers.
Sources
- Directive 2006/66/EC on batteries and accumulators, Article 21, Directive 2006/66/EC, Art. 21, legislation.gov.uk (The National Archives), Art. 21(3)
- The Batteries and Accumulators (Placing on the Market) Regulations 2008, regulation 6, SI 2008/2164, reg. 6, legislation.gov.uk (The National Archives), reg. 6
- Directive 2006/66/EC on batteries and accumulators, Annex II, Directive 2006/66/EC, Annex II, legislation.gov.uk (The National Archives), Annex II
- Substance restrictions and battery labelling (NetRegs), NetRegs (environmental guidance for business in Northern Ireland and Scotland), Using appropriate chemical symbols
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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