Mold vs. Mould
“Mold” and “mould” are regional spellings across the documented noun and verb senses: Cambridge labels mold as the US spelling of mould.
Use “mold” in US English and “mould” in UK English for the corresponding ordinary noun and verb senses.
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| US English across the corresponding ordinary noun/verb senses | mold | Use the US spelling. |
| UK English across the corresponding ordinary noun/verb senses | mould | Use the UK spelling. |
Quick tests
Meaning / construction test
Is the document following US English spelling?
If yes: Use “mold.”
If no: Use “mould” for UK English, subject to the governing house style.
Caveat: The spelling choice is regional; particular technical or proper-name uses should still follow the terminology required by the field or source.
Examples
The bread developed mold.
The US spelling is used for the noun.
The bread developed mould.
The UK spelling is used for the same noun sense.
They molded the material into shape.
The US spelling also carries through the related verb form.
Further guidance
Core difference
Use “mold” in US English and “mould” in UK English for the corresponding growth, container/shape, and shaping senses.
Fast Test
Match the form to the intended meaning, regional convention, or required house style, then keep that choice consistent.
Variant Boundary
This pair is a spelling variation, not a general meaning contrast; specialized proper names or house styles can still control.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Mold — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · US spelling of mould
- Mould — Cambridge Dictionary (opens in a new tab)Cambridge Dictionary · UK mould entry covering growth, shape/container, and related senses