Chilli products get to cite an actual Scoville number. Sour sweets mostly don't have an equivalent published figure, even though the underlying chemistry is just as measurable.
The measurable property is pH
Sourness is fundamentally a response to acidity, and pH is a genuine, standard scientific measure of how acidic a substance is. In principle, a sweet's pH could be measured and compared the same way Scoville units compare chilli heat. In practice, confectionery manufacturers don't typically publish this figure, so "how sour" comparisons between sweets are almost entirely informal — based on tasting, not a cited number.
What actually drives the sourness you taste
The concentration of acid in a sweet's coating or filling is the main factor — citric acid, malic acid and tartaric acid are the most common in confectionery, and a heavier or more concentrated coating delivers more acid to your tongue per bite than a lighter one, independent of which specific acid is used.
Why the same acid level doesn't always taste equally sour
Perceived sourness isn't purely a chemistry question. Malic acid is generally perceived as sharper than citric acid at a comparable concentration, so two sweets with similar overall acidity can still read as differently sour depending on which acid dominates. Texture and dissolve speed matter too — a coating that dissolves fast delivers its acid in a short, sharp burst, while a slower-dissolving one spreads the same total acid over more time and can taste less intense as a result, even with an identical total acid content.
Where this shows up in practice
It's part of why a genuinely wide range of sour sweets — from a mild sour dust on a gummy through to something built specifically to be as sour as possible, like our Warheads Extreme Sour range — can't be neatly ranked on a single agreed scale, even though every one of them is doing the same basic acid-on-tongue chemistry underneath.
Frequently asked questions
Is there an official sourness scale?
Not a published industry standard — pH is the real measurable property, but manufacturers don't typically publish it for sweets.
What actually determines sourness?
The concentration of acid (commonly citric, malic or tartaric) reaching your tongue, and how much of it is present.
Why do equally acidic sweets taste differently sour?
The specific acid used and how fast the coating dissolves both affect perceived intensity, not just the total acid content.