Candle Fill Height Calculator
Dividing 180 g by a density of 0.9 gives 200 ml, and a 7 cm inside diameter has a base area of 38.5 cm², so the wax stands 5.2 cm high. Knowing that height before pouring is how you check the wick tab is covered and the fill stays below the top of the label.
Your numbers
Wax height
5.2cm
Container volume
200mL
Base area
38.5cm²
Formula
Wax height = Wax needed ÷ Wax density ÷ (π × (Container diameter ÷ 2)²)
Wick tabs are 3–6 mm thick; wax shallower than that leaves the tab exposed and drives the last of the heat into the glass base. A tapered vessel fills higher than this, and entering a side length instead of a diameter for a square vessel reads low. Set the label below the wax line — a label sitting above the surface lifts as the candle warms.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Wax needed (g)The wax to melt, by weight. | 180 | 1 and up |
| Container diameter (cm)The inside diameter, excluding the glass wall. | 7 | 0.5 and up |
| Wax density (g/cm³)Grams per cm³ of wax — soy near 0.9, paraffin a little more. | 0.9 | 0.5 ~ 1.2 |
Step by step
Quick reference table
Results when only Wax needed (g) changes and everything else stays put.
| Wax needed (g) | Wax height (cm) | Container volume (mL) | Base area (cm²) |
|---|---|---|---|
| 90 | 2.6 | 100 | 38.5 |
| 135 | 3.9 | 150 | 38.5 |
| 180 | 5.2 | 200 | 38.5 |
| 270 | 7.8 | 300 | 38.5 |
| 360 | 10.4 | 400 | 38.5 |
What each result means
| Result | At default values |
|---|---|
| Wax height (cm)How high the wax stands inside the vessel, base to surface. | 5.2 |
| Container volume (mL)What the vessel holds; filling it with water is the accurate way. | 200 |
| Base area (cm²)The area of one base face. | 38.5 |
Common mistakes
Wick tabs are 3–6 mm thick; wax shallower than that leaves the tab exposed and drives the last of the heat into the glass base. A tapered vessel fills higher than this, and entering a side length instead of a diameter for a square vessel reads low. Set the label below the wax line — a label sitting above the surface lifts as the candle warms.
Glossary
- Wax needed
- The wax to melt, by weight.
- Container diameter
- The inside diameter, excluding the glass wall.
- Wax density
- Grams per cm³ of wax — soy near 0.9, paraffin a little more.
- Wax height
- How high the wax stands inside the vessel, base to surface.
- Container volume
- What the vessel holds; filling it with water is the accurate way.
- Base area
- The area of one base face.
Frequently asked questions
Q. How is Candle Fill Height Calculator calculated?
Wax height = Wax needed ÷ Wax density ÷ (π × (Container diameter ÷ 2)²) — Dividing 180 g by a density of 0.9 gives 200 ml, and a 7 cm inside diameter has a base area of 38.5 cm², so the wax stands 5.2 cm high. Knowing that height before pouring is how you check the wick tab is covered and the fill stays below the top of the label.
Q. Can you walk through an example?
With Wax needed 180g, Container diameter 7cm, Wax density 0.9g/cm³, the answer is Wax height 5.2cm.
Q. What do I need to enter?
Enter Wax needed, Container diameter, Wax density. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Wax needed (g) moves the answer to Wax needed (g) 90 → Wax height (cm) 2.6 and Wax needed (g) 360 → Wax height (cm) 10.4. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Wick tabs are 3–6 mm thick; wax shallower than that leaves the tab exposed and drives the last of the heat into the glass base. A tapered vessel fills higher than this, and entering a side length instead of a diameter for a square vessel reads low. Set the label below the wax line — a label sitting above the surface lifts as the candle warms.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.