Mold vs Mould: Spelling, Meaning and Which One to Use

Mold vs mould: they are the same word for the same fungus. Mold is the American spelling and mould is the British, Irish, Australian and common Canadian spelling. Both describe the fuzzy or slimy growth that appears on damp surfaces, food and fabrics. The spelling changes nothing about the health risk or how to remove it.

Mold vs mould: which spelling is right

Neither is wrong. American English drops the u in many words, such as color and honor, and mold follows that pattern. British English keeps it, as in colour and mould. If you write for a US audience, use mold. If your readers are in the UK, Ireland, Australia or New Zealand, use mould. Canadians use both, but mould is common.

Quick facts: mold vs mould
Meaning	A fungus that grows as fuzzy, slimy or powdery patches on damp materials
United States	Mold
UK, Ireland, Australia, NZ	Mould
Canada	Mould and mold are both seen

The same thing, in other words

Phrase	American	British
Growth in a damp bathroom	Bathroom mold	Bathroom mould
Black patches on walls	Black mold	Black mould
Removal service	Mold remediation	Mould removal
Insurance wording	Mold coverage	Mould cover

Mold vs mildew

Mold and mildew are both fungi, but people use the words differently. Mildew usually means a flat, powdery growth that is white, gray or yellowish and grows on the surface of plants or damp household materials such as shower tiles. Mold often means thicker, fuzzier or darker patches that spread into materials. Both need moisture, and both should be cleaned and the damp fixed.

Why mold grows

Mold spores float in the air everywhere. They need moisture, a food source such as wood, paper, fabric or dust, and time. Leaks, flooding, condensation and high humidity provide the water, and growth can start within one to two days on wet materials.

What it looks like

Colors include black, green, white, gray, orange and brown. Texture can be fuzzy, slimy, powdery or cottony. The color alone does not tell you the species or the risk, so treat any indoor growth the same way: find the moisture, dry the area, clean or remove the growth.

Health and safety

Mold can irritate eyes, nose, throat and skin and trigger allergy and asthma symptoms. People with weak immune systems or lung disease are at higher risk. The spelling of the word does not change this. Wear gloves, goggles and a respirator when you clean, and avoid stirring up dust.

What to do in either spelling

1. Fix the water source.
2. Dry wet materials within a day or two.
3. Clean hard surfaces with detergent and water.
4. Remove soaked or heavily moldy porous materials such as drywall, carpet and ceiling tiles.
5. Keep humidity between about 30 and 50 percent with ventilation or a dehumidifier.

Where you will see each spelling

Many brands and sites choose one spelling and stay with it. American agencies, hardware stores and insurers write mold. British and Australian sources generally write mould. Dictionaries list both, usually noting which is American. If you are searching, try both spellings, because some pages use only one and you may miss helpful guides.

Related words

The spelling difference applies to related words too: molding and moulding for decorative trim, moldy and mouldy, and moldering and mouldering. In a house, molding on a wall edge is trim, not fungus, so check the context before reading a word.

A quick way to remember

Think of the American habit of shortening words: color, honor, mold. The British keep the u: colour, honour, mould. Both are right in their own country, and neither changes how you treat the problem on your walls.

When to call a professional

If the growth covers more than about 10 square feet, is inside walls, follows flooding or sewage, or returns after cleaning, call a remediation company. Whether you search for mold vs mould or any other phrase, the safe response is the same.

Mold vs mould: the same organism, two spellings

Mold vs mould is a question of spelling, not of the organism. Mold is the American spelling and mould is the British one, and both describe the same fungus that grows on damp surfaces. Mold vs mildew is a different comparison: mildew usually refers to surface growth that is flat and powdery, while mold can be fuzzy and can penetrate materials. Whichever spelling you use, the health and cleaning advice is the same. Control the moisture first, then clean the surface.

When you search for help, you may see both mold vs mould spellings, but the advice is identical.

Related reading

• Black Mold vs Mildew: How to Tell Them Apart and What to Do
• Mold After Water Damage: How Fast It Grows and What to Do
• Does Homeowners Insurance Cover Mold? What Policies Usually Say
• Mold Under Kitchen Sink: Find the Leak, Clean It, Stop Regrowth

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