diff --git a/src/strings.cpp b/src/strings.cpp
--- a/src/strings.cpp
+++ b/src/strings.cpp
@@ -96,25 +96,27 @@ void StringParameters::ShiftParameters(u
  * @param max_value The biggest value which shall be displayed.
  *                  For the result only the number of digits of \a max_value matter.
  * @param min_count Minimum number of digits independent of \a max.
+ * @param size  Font of the number
  */
-void SetDParamMaxValue(uint n, uint64 max_value, uint min_count)
+void SetDParamMaxValue(uint n, uint64 max_value, uint min_count, FontSize size)
 {
 	uint num_digits = 1;
 	while (max_value >= 10) {
 		num_digits++;
 		max_value /= 10;
 	}
-	SetDParamMaxDigits(n, max(min_count, num_digits));
+	SetDParamMaxDigits(n, max(min_count, num_digits), size);
 }
 
 /**
  * Set DParam n to some number that is suitable for string size computations.
  * @param n Index of the string parameter.
  * @param count Number of digits which shall be displayable.
+ * @param size  Font of the number
  */
-void SetDParamMaxDigits(uint n, uint count)
+void SetDParamMaxDigits(uint n, uint count, FontSize size)
 {
-	static const uint biggest_digit = 8; ///< Digit with the biggest string width.
+	uint biggest_digit = GetBroadestDigit(size);
 	uint64 val = biggest_digit;
 	for (; count > 1; count--) {
 		val = 10 * val + biggest_digit;