How to Trim a Candle Wick Properly

Trim the wick to 5 mm before every burn, using nail scissors or a wick trimmer on a cool, fully set candle. Remove the trimmed piece from the wax. This prevents soot and mushrooming, and adds roughly 20–30% to total burn time.

The method

1. Wait until the candle is cold and set. Trimming a warm candle drops debris into liquid wax where you cannot retrieve it.
2. Trim to 5 mm. About the width of a grain of rice above the wax surface.
3. Remove the trimmed piece. Left behind, it becomes a second wick and a fire risk.
4. Cut straight across, not at an angle.

Nail scissors work fine. A dedicated wick trimmer is easier on a jar that has burned down, where scissors cannot reach the wick cleanly.

Why it matters more than people think

An untrimmed wick burns a taller flame. A taller flame melts more wax per hour, so the candle disappears faster and the fragrance burns off rather than diffusing. It also produces soot, which is what leaves a black rim on a jar.

The bulbous carbon ball on a neglected wick — mushrooming — is unburned carbon. It drops into the wax, discolours it, and makes the flame flare.

Wooden wicks are different

Wooden wicks need to be shorter, around 3 mm, and are trimmed by pinching off the charred top with your fingers once cold rather than cutting. If a wooden wick struggles to stay lit, it is almost always too long.

Common mistakes

Trimming too short — below about 3 mm the flame drowns in its own melt pool and keeps going out. Trimming while warm, which contaminates the wax. And leaving the trimmed piece in the pool, which is the one that actually matters for safety.

Frequently asked questions

How short should a candle wick be?

5 mm for cotton wicks, about 3 mm for wooden ones. Shorter than that and the flame drowns.

What can I use if I don't have a wick trimmer?

Nail scissors are perfectly adequate. Kitchen scissors work on a new candle but not once it has burned down into the jar.

When should I trim the wick?

Before every single burn, on a cold candle. Not while it is lit or still warm.

Why does my wick keep mushrooming?

It is being burned too long without trimming, or the wick is slightly oversized for the vessel. Trim before each burn and it should stop.

What if I forget to trim it?

Blow the candle out, let it set completely, trim it, then relight. You will lose some wax to soot, not the candle.