Figure/Table floats and \label placement: must it follow \caption to bind the right number?

Short answer

Yes. In standard LaTeX classes (article, report, book), \label must come after \caption — or be placed inside the caption argument — to bind to the float's number. A \label placed before \caption is not a style choice; it is a correctness bug that silently references the wrong counter (typically the current section number).

Why placement matters

\label does not know which counter you intend. It records whatever counter was most recently stepped by \refstepcounter. Inside a figure or table environment, it is \caption that steps the float counter. So the sequence determines the binding:

• \caption{...}\label{fig:x} — label captures the figure/table number. Correct.
• \caption{\label{fig:x} ...} — also correct; the counter is stepped before the caption text is typeset.
• \label{fig:x}\caption{...} — label captures whatever was stepped last, usually the section counter. \ref{fig:x} then prints something like "3.2" instead of the figure number, with no warning.

Templates that put \label first

If a template places \label before \caption and its cross-references appear correct, the likely explanation is that the references were never actually checked against the printed float numbers, or the document's section and figure numbers happened to coincide in early drafts. It is not engine- or class-dependent magic. Treat it as a latent bug and move the label.

Unnumbered \caption*

\caption* (from the caption package) typesets a caption without stepping the counter. A \label after it therefore has no new float number to bind to — it captures the previously stepped counter, exactly like the before-\caption case. If you need a referenceable float, use a numbered \caption. For an unnumbered float, referencing by number is not meaningful; use \pageref if you only need the page.

Engines and packages

The counter-stepping behavior is identical across pdfLaTeX, XeLaTeX, and LuaLaTeX, because it lives in LaTeX's macro layer, not the engine. Packages such as caption, hyperref, or custom float environments may redefine \caption, but well-behaved redefinitions still step the counter inside the caption command, so the after-\caption rule holds. (If you use a heavily customized float package, verify as below rather than assuming.)

Verifying via the .aux file

Compile twice, then inspect the .aux entry for your label:

grep 'fig:x' mydoc.aux

You will see a \newlabel{fig:x}{{1}{2}...} entry (or the \newtarget equivalent with hyperref). The first brace group is the captured counter value. If it matches the printed float number, placement is correct; if it shows the section number, the label is in the wrong position. A minimal test document with one figure and deliberately swapped label positions makes the difference obvious in a single compile.