I'm typing up a document where I'd like to add notes to myself on the side margin. I'm using marginnote and using the geometry package for specifying customized margins, I've allocated 5 cm for the left margin, but no matter how long the note is, it doesn't take up the whole 5 cm. Does anyone know why this is happening and is there a way to fix this?

Here's my code:

\usepackage[top=2cm, bottom=1.3cm, left=5cm, right=0.5cm]{geometry}

\Large \underline{Chapter 7 \textsc{Enzyme Kinetics \& Inhibition}}  

\section*{Introduction to Enzyme Kinetics}
  \1 Structural information doesn't give any information about enzyme's physiological role
    \marginnote{{\small So what do we need to figure that out?}}



So I downloaded the user guide to marginnote, and it says that I have to define the real width of the type area using \marginnotetextwidth. It says,

Package marginnote needs to know the real width of the type area to find the right margin. While some environments (e.g. thos of package framed) change \textwidth, marginnote defines it’s own text width macro. If you change type area after \begin{document} you should add


after changing the type area. Maybe you should do this globally using \xdef instead of \edef. Most users will never need to change \marginnotetextwidth.

Does that mean I have to do this in the preamble or in the package itself? I'm a little confused as I tried to add \marginnotetextwidth{5cm} in the preamble but the compiler tells me, "Missing number, treated as zero."

2 Answers 2


You have to tell geometry also the desired width of your marginal notes. Keep also into account that there is the parameter \marginparsep that should be non zero. Therefore something like

\usepackage[top=2cm, bottom=1.3cm, left=5cm, right=0.5cm, heightrounded,
  marginparwidth=4.6cm, marginparsep=3mm]{geometry}

should be what you want (4.6+0.3=4.9, so 1mm will be kept clear at the left edge).

The option heightrounded has nothing to do with the problem at hand, but it's better to specify it so that TeX will have less problems filling pages.


After struggling, Googling and getting very angry with LaTeX, I figured out what I had to do: I use \marginparwidth=%some_cm in the preamble to specify my margin width while still using \marginnote. The code may seem awkward, but it works for me.

  • 6
    Or, alternatively, \setlength{\marginparwidth}{5cm} does the same thing, in a slightly cleaner (IMHO) way. Feb 5, 2014 at 8:04
  • This solution often works better than manually defining the geometry for the whole document when using an existing style file.
    – danijar
    Sep 22, 2019 at 22:12

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