Free, no account needed, sized for a phone at the bench
The maths, done.
Calculators for people making things in small batches. Every one shows its working, so you can check the number instead of trusting it.
- Net wt. Candle wax calculator How much wax a batch needs, with headspace and fragrance displacement accounted for Open
- F.O. Fragrance load calculator Oil weight for a wax weight you already have, under either load convention Open
- $ / ea Candle cost calculator Cost per candle including your labour, then wholesale and retail pricing Open
- ml Reed diffuser calculator Base and fragrance split for any bottle size and batch Open
- Price Handmade pricing calculator Wholesale, retail and consignment prices for candles, soap, resin, body care or anything else you make in batches Open
- Soon Soap lye & superfat Not built yet - in the queue behind the candle benches -
- Soon Resin & hardener ratios Not built yet - by volume and by weight -
Why the working is shown
Most calculators hand you a number and nothing else. That's fine until the number looks wrong, at which point you have no way to tell whether the tool is mistaken or your assumption is - so you do the arithmetic by hand anyway, and the tool has saved you nothing.
Every bench here prints the formula it used, the densities and constants behind it, and a worked example with real figures. Check it once, trust it after.
Who makes this
Formula Bench is built by Lavender Ink. Lavender Ink exists so that everyone gets an equal chance to experience clean luxury, whatever their sensory capacity.
That work happens in three ways. We build communities where people come together, share experiences and draw strength from each other. We host events around each of the senses, so those communities have somewhere to meet. And we make products for every sensory medium - starting with candles and diffusers, and filling out from there.
The calculations on this site come out of that making: pouring actual batches and getting them wrong in the usual ways. Jars overfilled by exactly the fragrance percentage, wholesale orders priced without counting labour, diffusers that went cloudy overnight.
Where a figure is a starting default rather than a law of physics, the page says so.
The apps
Chandler covers the candle calculations and Waft covers diffusers, both on iOS. Epoxio, for resin and casting, is next, and more will follow as the benches here grow. Everything on this site is free and stays free - the apps are for when you want your vessels, waxes and batches saved rather than re-entered each time.
Something missing?
If there's a calculation you keep doing on paper, it's worth saying so. The queue is short and reader requests move up it.