This webpage allows you to obtain the predicted perceptual similarity, expressed in radians, between any pair of complex odorant formulas. The calculation is based on a study by Ravia et al (2020) published in the journal Nature.

The higher the value in radians, the more perceptually different the odorants. Odorants less than 0.05 radians apart are very similar to each other, and odorants less than 0.0125 radians apart are likely indiscriminable by most people.

OdorSpace has a *basic* and *advanced* interface. Here we will explain how to use the *basic*. To use the *advanced*, click on *advanced*, and then click again on *information* (i) to get advanced-specific instructions.

__How to use OdorSpace Basic__

The main image contains about 4000 mono-molecules depicted in 3-dimensional space, where the X-axis reflects estimated pleasantness (r = ~0.6) based on a model from odorant structure as detailed in Snitz et al (2019), such that larger values imply greater pleasantness. The remaining axes together reflect the pairwise distances between the odorant molecules. You can click on any molecule to get its coordinates, identifiers, and its descriptors if available. When you select an odorant formula, its molecular components will be highlighted in a corresponding color.

In OdorSpace Basic you can compare only between previously created formulas. These are formulas for common odorants that have been contributed by users. Currently the list is short, but we hope it will now grow fast with new formulas contributed by users, and soon will contain any odorant one might be familiar with.

__To compare up to three formulas:__

1. In the "Select Formula Number" pane highlight "Form. 1"

2. Use the "Assign contents" bar to select an odorant (e.g.,"rose")

3. In the "Select Formula Number" pane highlight "Form. 2"

4. Use the "Assign contents" bar to select a different odorant (e.g.,"violet")

5. Press "Calculate" (You can also add a third formula in Form. 3 before calculating)

Click "reset" to start over.