The human nose can detect one trillion different odours, according to new estimates published in the Science magazine.
The scientific literature typically claims that humans can discriminate 10,000 odours.
The human nose outperforms the eye and the ear in terms of the number of stimuli it can distinguish between, the estimates suggests.
Researchers at the Rockefeller University say we use only a tiny part of our olfactory powers.
The human eye uses three light receptors that work together to see up to 10 million colours, while the ear can hear almost half a million tonnes.
The researchers devised experiments to see how good people are at distinguishing between cocktails of 128 different odour molecules, representing a large range of smells from grass to citrus.
The molecules were mixed randomly in groups of 10, 20 or 30 to create unfamiliar smells.
The 26 people were then asked to identify a scent from three samples - two that were the same and one that was different.
Based on these results, the researchers used theory to extrapolate how many different scents the average person would be able to discriminate if they were presented with all the possible mixtures that could be made from the 128 molecules.