Methodology
How we check the numbers
Every calculator on this site does simple arithmetic. The hard part is choosing the right inputs and conventions, because candle makers and suppliers do not always use the same ones. This page lists the choices we made and how we tested them.
Units
We use the avoirdupois ounce (28.3495 g) and pound (453.592 g) for weight, and the US fluid ounce (29.5735 ml) for jar volume. Fluid ounces measure space, ounces measure weight; we never treat them as the same thing.
Fill factor
Finished candle weight = water weight × 0.86 (editable). This is the factor Candles Molds and most supply shops use. Some calculators multiply a jar’s fl oz number directly as if it were ounces of water, which gives about 4% less than converting through milliliters; we convert properly.
Fragrance load
By default a load is a percent of wax weight, as most US suppliers write it: wax = total ÷ (1 + load), oil = total − wax. You can switch to percent of the whole candle, as Craftybase uses: oil = total × load. Every result shows both forms.
What we tested against
| Check | Their result | Ours |
|---|---|---|
| Candles Molds: 8 oz candle at 8% (of wax) | 7.41 oz wax, 0.59 oz oil | 7.41, 0.59 |
| Candles Molds: 3 × 4 in cylinder volume | 463 ml | 463.3 ml |
| Craftybase: 6.88 oz at 6% of total | 0.41 oz oil | 0.41 |
| Lone Star: 1 lb wax at 8% | 1.28 oz oil | 1.28 |
| Lone Star: 10% as oz per lb | 1.6 oz/lb | 1.6 |
| Reddit worked example: 16 oz candle at 10% | 14.55 oz wax, 1.45 oz oil | 14.55, 1.45 |
These checks run as automated tests every time the site is built, along with tests for label rounding, fee math, postage tiers and wick sizes.
Supplier data
Wax limits and temperatures on the wax specs page are copied as written from the linked pages and sheets, last checked 2026-10-21. Starting wicks come from the CandleScience wick guide. Dye rates come from Lone Star, Candles Molds and CandleScience.
Rules and fees
Label rules come from 16 CFR Part 500, the FTC’s regulations under the Fair Packaging and Labeling Act. Etsy and Shopify fees come from their published fee pages, and postage tiers from USPS Ground Advantage. Fees and postage change; each calculator shows the date we last checked.
Rounding
Weights for the bench are shown to two decimals in ounces and whole grams. Label net weights are always rounded down, so a label never claims more than the container holds.