diff --git a/R/class-workbook-wrappers.R b/R/class-workbook-wrappers.R
index c04f0fbdd..6bcaae284 100644
--- a/R/class-workbook-wrappers.R
+++ b/R/class-workbook-wrappers.R
@@ -3400,11 +3400,61 @@ wb_add_font <- function(
 #' Add number formatting to a cell region. You can use a number format created
 #' by [create_numfmt()].
 #'
-#' The list of number formats ID is located in the **Details** section of [create_cell_style()].
 #' @param wb A Workbook
 #' @param sheet the worksheet
 #' @param dims the cell range
-#' @param numfmt either an id or a character
+#' @param numfmt either an integer id for a builtin numeric font or a character string as described in the ***Details***
+#'
+#' @details
+#' The list of number formats ID is located in the **Details** section of [create_cell_style()].
+#'
+#' ### General Number Formatting
+#' - `"0"`: Displays numbers as integers without decimal places.
+#' - `"0.00"`: Displays numbers with two decimal places (e.g., `123.45`).
+#' - `"#,##0"`: Displays thousands separators without decimals (e.g., `1,000`).
+#' - `"#,##0.00"`: Displays thousands separators with two decimal places (e.g., `1,000.00`).
+#'
+#' ### Currency Formatting
+#' - `"$#,##0.00"`: Formats numbers as currency with two decimal places (e.g., `$1,000.00`).
+#' - `"[$$-409]#,##0.00"`: Localized currency format in U.S. dollars.
+#' - `"¥#,##0"`: Custom currency format (e.g., for Japanese yen) without decimals.
+#' - `"£#,##0.00"`: GBP currency format with two decimal places.
+#'
+#' ### Percentage Formatting
+#' - `"0%"`: Displays numbers as percentages with no decimal places (e.g., `50%`).
+#' - `"0.00%"`: Displays numbers as percentages with two decimal places (e.g., `50.00%`).
+#'
+#' ### Scientific Formatting
+#' - `"0.00E+00"`: Scientific notation with two decimal places (e.g., `1.23E+03` for `1230`).
+#'
+#' ### Date and Time Formatting
+#' - `"yyyy-mm-dd"`: Year-month-day format (e.g., `2023-10-31`).
+#' - `"dd/mm/yyyy"`: Day/month/year format (e.g., `31/10/2023`).
+#' - `"mmm d, yyyy"`: Month abbreviation with day and year (e.g., `Oct 31, 2023`).
+#' - `"h:mm AM/PM"`: Time with AM/PM format (e.g., `1:30 PM`).
+#' - `"h:mm:ss"`: Time with seconds (e.g., `13:30:15` for `1:30:15 PM`).
+#' - `"yyyy-mm-dd h:mm:ss"`: Full date and time format.
+#'
+#' ### Fraction Formatting
+#' - `"# ?/?"`: Displays numbers as a fraction with a single digit denominator (e.g., `1/2`).
+#' - `"# ??/??"`: Displays numbers as a fraction with a two-digit denominator (e.g., `1 12/25`).
+#'
+#' ### Custom Formatting
+#' - `"_($* #,##0.00_);_($* (#,##0.00);_($* "-"??_);_(@_)`:
+#'   Custom currency format with parentheses for negative values and dashes for zero values.
+#' - `"[Red]0.00;[Blue](0.00);0"`: Displays positive numbers in red, negatives in blue, and zeroes as plain.
+#' - `"@"`: Text placeholder format (e.g., for cells with mixed text and numeric values).
+#'
+#' ### Formatting Symbols Reference
+#' - `0`: Digit placeholder, displays a digit or zero.
+#' - `#`: Digit placeholder, does not display extra zeroes.
+#' - `.`: Decimal point.
+#' - `,`: Thousands separator.
+#' - `E+`, `E-`: Scientific notation.
+#' - `_` (underscore): Adds a space equal to the width of the next character.
+#' - `"text"`: Displays literal text within quotes.
+#' - `*`: Repeat character to fill the cell width.
+#'
 #' @examples
 #' wb <- wb_workbook() %>% wb_add_worksheet("S1") %>% wb_add_data("S1", mtcars)
 #' wb %>% wb_add_numfmt("S1", dims = "F1:F33", numfmt = "#.0")
diff --git a/R/wb_styles.R b/R/wb_styles.R
index f1107b6f3..d2eaae167 100644
--- a/R/wb_styles.R
+++ b/R/wb_styles.R
@@ -173,8 +173,11 @@ create_border <- function(
 #' @export
 create_numfmt <- function(numFmtId, formatCode) {
 
-  # maybe only required in dates
-  formatCode <- escape_forward_slashes(formatCode)
+  # in dates a slash does not indicate a fraction, but can be used to
+  # separate year, month, day
+  if (grepl("(y{2,4}|m{1,4}|d{1,2})", tolower(formatCode)) && grepl("/", formatCode)) {
+    formatCode <- escape_forward_slashes(formatCode)
+  }
 
   df_numfmt <- data.frame(
     numFmtId         = as_xml_attr(numFmtId),
diff --git a/man/wb_add_numfmt.Rd b/man/wb_add_numfmt.Rd
index f2b22b91f..9c2fcdac3 100644
--- a/man/wb_add_numfmt.Rd
+++ b/man/wb_add_numfmt.Rd
@@ -13,7 +13,7 @@ wb_add_numfmt(wb, sheet = current_sheet(), dims = "A1", numfmt)
 
 \item{dims}{the cell range}
 
-\item{numfmt}{either an id or a character}
+\item{numfmt}{either an integer id for a builtin numeric font or a character string as described in the \emph{\strong{Details}}}
 }
 \value{
 The \code{wbWorkbook} object, invisibly.
@@ -24,6 +24,76 @@ by \code{\link[=create_numfmt]{create_numfmt()}}.
 }
 \details{
 The list of number formats ID is located in the \strong{Details} section of \code{\link[=create_cell_style]{create_cell_style()}}.
+\subsection{General Number Formatting}{
+\itemize{
+\item \code{"0"}: Displays numbers as integers without decimal places.
+\item \code{"0.00"}: Displays numbers with two decimal places (e.g., \code{123.45}).
+\item \code{"#,##0"}: Displays thousands separators without decimals (e.g., \verb{1,000}).
+\item \code{"#,##0.00"}: Displays thousands separators with two decimal places (e.g., \verb{1,000.00}).
+}
+}
+
+\subsection{Currency Formatting}{
+\itemize{
+\item \code{"$#,##0.00"}: Formats numbers as currency with two decimal places (e.g., \verb{$1,000.00}).
+\item \code{"[$$-409]#,##0.00"}: Localized currency format in U.S. dollars.
+\item \code{"¥#,##0"}: Custom currency format (e.g., for Japanese yen) without decimals.
+\item \code{"£#,##0.00"}: GBP currency format with two decimal places.
+}
+}
+
+\subsection{Percentage Formatting}{
+\itemize{
+\item \code{"0\%"}: Displays numbers as percentages with no decimal places (e.g., \verb{50\%}).
+\item \code{"0.00\%"}: Displays numbers as percentages with two decimal places (e.g., \verb{50.00\%}).
+}
+}
+
+\subsection{Scientific Formatting}{
+\itemize{
+\item \code{"0.00E+00"}: Scientific notation with two decimal places (e.g., \code{1.23E+03} for \code{1230}).
+}
+}
+
+\subsection{Date and Time Formatting}{
+\itemize{
+\item \code{"yyyy-mm-dd"}: Year-month-day format (e.g., \code{2023-10-31}).
+\item \code{"dd/mm/yyyy"}: Day/month/year format (e.g., \code{31/10/2023}).
+\item \code{"mmm d, yyyy"}: Month abbreviation with day and year (e.g., \verb{Oct 31, 2023}).
+\item \code{"h:mm AM/PM"}: Time with AM/PM format (e.g., \verb{1:30 PM}).
+\item \code{"h:mm:ss"}: Time with seconds (e.g., \code{13:30:15} for \verb{1:30:15 PM}).
+\item \code{"yyyy-mm-dd h:mm:ss"}: Full date and time format.
+}
+}
+
+\subsection{Fraction Formatting}{
+\itemize{
+\item \code{"# ?/?"}: Displays numbers as a fraction with a single digit denominator (e.g., \code{1/2}).
+\item \code{"# ??/??"}: Displays numbers as a fraction with a two-digit denominator (e.g., \verb{1 12/25}).
+}
+}
+
+\subsection{Custom Formatting}{
+\itemize{
+\item \verb{"_($* #,##0.00_);_($* (#,##0.00);_($* "-"??_);_(@_)}:
+Custom currency format with parentheses for negative values and dashes for zero values.
+\item \code{"[Red]0.00;[Blue](0.00);0"}: Displays positive numbers in red, negatives in blue, and zeroes as plain.
+\item \code{"@"}: Text placeholder format (e.g., for cells with mixed text and numeric values).
+}
+}
+
+\subsection{Formatting Symbols Reference}{
+\itemize{
+\item \code{0}: Digit placeholder, displays a digit or zero.
+\item \verb{#}: Digit placeholder, does not display extra zeroes.
+\item \code{.}: Decimal point.
+\item \verb{,}: Thousands separator.
+\item \verb{E+}, \verb{E-}: Scientific notation.
+\item \verb{_} (underscore): Adds a space equal to the width of the next character.
+\item \code{"text"}: Displays literal text within quotes.
+\item \code{*}: Repeat character to fill the cell width.
+}
+}
 }
 \examples{
 wb <- wb_workbook() \%>\% wb_add_worksheet("S1") \%>\% wb_add_data("S1", mtcars)