Is the -OCH3 group bulky?

Our teacher told us that $\ce{OCH3}$ is a less bulky group when compared to other bulky groups like $\ce{CH3}$, $\ce{NO2}$ etc. Is this true? If yes, why?




In organic chemistry bulkiness isn't just a matter of geometry; one can find the volume of the group using vdW radii, but it's a crude approximation.
Quantitatively steric bulk relies on energy measurements and can be described with a [cyclohexane A-value](https://en.wikipedia.org/wiki/A_value) — energy required for a group to switch between axial and equatorial positions in cyclohexane.
From the table of A-values methoxy group is indeed less bulk in comparison to nitro and methyl groups:


$$
\begin{array}{lc}
\hline
\text{Substituent} & \text{A-Value}/\pu{kcal mol-1} \\
\hline
\ce{-OCH3} & 0.6 \\
\ce{-NO2} & 1.1 \\
\ce{-CH3} & 1.7 \\
\hline
\end{array}
$$


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