[Tex/LaTex] Unexpected “Float too large for page”

floatsspacingwarnings

My client wants the illustrations in her book to have the page to themselves,
so I’ve been using code like this for the floats:

\documentclass{memoir}

% Page layout: 6″×9″ , no trim; type-block: 4.75″×7.5″
\setstocksize{9in}{6in} \settrimmedsize{9in}{6in}{*} \settrims{0in}{0in}
\setbinding{0.375in} \setlrmarginsandblock{0.375in}{0.5in}{*} \setulmarginsandblock{0.75in}{0.75in}{*}

\usepackage{calc}
\setheadfoot{\baselineskip}{\topskip + \baselineskip} \setheaderspaces{*}{\topskip}{*} \setmarginnotes{0.25\spinemargin}{0.5\spinemargin}{0pt}

\checkandfixthelayout[nearest]

\usepackage{graphicx}

\begin{document}
\begin{figure}
  % type-block is 4.75″×7.5″, picture is 2850×2850 @600dpi = 4.75″×4.75″,
  % so add (7.5″−4.75″)÷2 = 1.375″ vspace on each side of the picture
  % to force it to occupy a full page
  \vspace{1.375in}
  \centering
  \includegraphics{illustration.png}
  \vspace{1.375in}
\end{figure}
\end{document}

Despite my math, I’m getting the message, “LaTeX Warning: Float too large for page by 16.02414pt on input line 23.”

Following the answers to How can I get rid of the LaTeX warning: Float too large for page?, I can certainly reduce the vspace I’m adding, but I’d like to understand where the error is coming from. What am I not accounting for that’s eating 14–16 points in every picture?

Best Answer

Let TeX do the computations:

\documentclass{memoir}
\usepackage{calc}
\usepackage{graphicx}

\setstocksize{9in}{6in}
\settrimmedsize{9in}{6in}{*}
\settrims{0in}{0in}
\setbinding{0.375in}
\setlrmarginsandblock{0.375in}{0.5in}{*}
\setulmarginsandblock{0.75in}{0.75in}{*}

\setheadfoot{\baselineskip}{\topskip + \baselineskip}
\setheaderspaces{*}{\topskip}{*}
\setmarginnotes{0.25\spinemargin}{0.5\spinemargin}{0pt}

\checkandfixthelayout[nearest]

\begin{document}

\begin{figure}

\begin{minipage}[c][\textheight]{\textwidth}
\centering
\rule{4.75in}{4.75in}
%\includegraphics{illustration.png}
\end{minipage}

\end{figure}

\end{document}
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