How much headroom should I leave in a candle container?

Leave 10-15 mm of space from the top of the container. This prevents wax from overflowing when the candle is burning and gives a clean, professional appearance. It also keeps the flame safely below the rim of the container.

Why does wax shrink after pouring?

Wax contracts as it cools from liquid to solid. Soy wax shrinks about 5%, paraffin about 8%. This creates sinkholes around the wick. To compensate, pour at the correct temperature and do a second (top-up) pour to fill any sinkholes after the first pour has set.

How do I convert container volume to wax weight?

Multiply the fill volume in ml by the wax density. Soy wax has a density of about 0.86 g/ml, so 100 ml of container space needs roughly 86 g of soy wax. Add extra for shrinkage and fragrance oil weight is in addition to wax weight.

What fragrance load should I use?

Most wax types have a maximum fragrance load of 8-10%. Soy wax typically handles 6-10%, paraffin 6-8%. Exceeding the maximum can cause sweating, poor adhesion and safety issues. Start at 6-8% and test burn before increasing.

CraftCalcs

Container Fill Calculator — Wax Weight for Candle Containers

Calculate wax weight needed to fill containers with headroom allowance.

Container Shape

Shape of your candle container

Internal Diameter

Internal diameter of the container

Container Height

Internal height of the container

Headroom

Gap from wax surface to container rim

Wax Type

Determines density and pouring temperature

Fragrance Load

Fragrance oil as percentage of wax weight

How We Calculate This

Fill Volume

Fill volume = Container volume x (Fill height / Total height)

Wax Weight

Wax weight = Fill volume x Wax density x (1 + Shrinkage %)

Fragrance oil weight is calculated as a percentage of the wax weight and added to the total pour weight.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify quantities before purchasing materials.