What does a Scoville number actually mean?
It is a dilution. In the original test, a chilli extract was watered down until the heat could no longer be tasted, and the number of times it was diluted became the rating (Bosland and Walker, 2010; BfR, 2024), in Scoville heat units (SHU). Pick a chilli and see what that looks like.
Try it
In hot tubs
How it compares
Each bar shows the amount of sugar water needed across the published range for this chilli. The scale is logarithmic, so each gridline is ten times more than the one before.
Axis: sugar water, in litres unless marked (ml is millilitres, m is million). The dashed markers show everyday volumes for comparison.
How to read this
A rating of 5,000 SHU means the extract had to be diluted about 5,000 times before the tasters could no longer detect any heat (Bosland and Walker, 2010). As a worked example, not a measurement of any chilli, this page takes the middle of each chilli's published range and shows what that would mean for one spoonful of extract. A teaspoon of extract at 5,000 SHU needs about 5,000 teaspoons of sugar water, which is roughly 25 litres.
Two things to keep in mind:
- It is the extract that is diluted, not the whole chilli. A teaspoon of extract is not a teaspoon of chopped pepper.
- Today's figures are usually calculated, not tasted. Laboratories now measure capsaicin with a machine and convert the result to the equivalent Scoville number. So the dilution shown here is what the number is equivalent to, not a test someone carried out.
The glass (250 millilitres) is our own round figure, for illustration. The bathtub is about 235 litres (NIST, 2026). The hot tub is taken as about 1,250 litres, the United Utilities figure for an average four-seater (United Utilities, no date). Tubs vary a lot: that page gives about 3,000 litres for a seven-seater, and two tub retailers give 300 to 450 US gallons (about 1,100 to 1,700 litres) for a standard four to six person tub (E-Konomy, no date; AquaLife Hot Tubs, 2026). They do not say which gallon they mean, so we have assumed the US gallon (3.785 litres). The Olympic pool is about 2.5 million litres, from a 50 metre by 25 metre pool at the minimum depth of 2 metres (Wikipedia, no date b). The pool is a loose unit, since there is no maximum depth, and the US National Institute of Standards and Technology rounds it to 1 million litres as an everyday comparison (NIST, 2026). We use the 2.5 million figure because it follows from the competition rules, and a deeper pool holds more.
References
- AquaLife Hot Tubs (2026) 'Hot tub sizes and their average water capacity', AquaLife Hot Tubs blog, 23 January. Available at: https://aqualifehottubs.com/blog/water-capacity/ (Accessed: 11 October 2026).
- Bosland, P.W. and Walker, S.J. (2010) Measuring chile pepper heat. Guide H-237. Las Cruces: New Mexico State University. Available at: https://pubs.nmsu.edu/_h/H237/ (Accessed: 11 October 2026).
- E-Konomy Pool Service & Supplies (no date) How much water does a hot tub hold?. E-Konomy blog (posted 29 July, year not shown). Available at: https://www.e-konomy.com/post/how-much-water-does-hot-tub-hold (Accessed: 11 October 2026).
- German Federal Institute for Risk Assessment (BfR) (2024) High capsaicin levels can harbour health risks. Opinion No. 027/2024, 21 June. English translation; the German text is the legally binding version. Berlin: BfR. Available at: https://doi.org/10.17590/20240704-110826-0 (Accessed: 11 October 2026).
- National Institute of Standards and Technology (NIST) (2026) SI units: volume. Office of Weights and Measures, page updated 2 March 2026. Available at: https://www.nist.gov/pml/owm/si-units-volume (Accessed: 11 October 2026).
- United Utilities (no date) How much water does my hot tub use?. Available at: https://corporate.unitedutilities.com/your-questions-answered/Saving-water/how-much-water-does-my-hot-tub-use/ (Accessed: 11 October 2026).
- Wikipedia (no date b) Olympic-size swimming pool. Available at: https://en.wikipedia.org/wiki/Olympic-size_swimming_pool (Accessed: 11 October 2026).
Read more on how the Scoville scale works, or go back to the chart.