diff --git a/fpdf.go b/fpdf.go
index 3be1cdc..7bccda7 100644
--- a/fpdf.go
+++ b/fpdf.go
@@ -67,6 +67,7 @@ func fpdfNew(orientationStr, unitStr, sizeStr, fontDirStr string, size SizeType)
 	if unitStr == "" {
 		unitStr = "mm"
 	}
+
 	if sizeStr == "" {
 		sizeStr = "A4"
 	}
@@ -3482,7 +3483,29 @@ func (f *Fpdf) getpagesizestr(sizeStr string) (size SizeType) {
 	sizeStr = strings.ToLower(sizeStr)
 	// dbg("Size [%s]", sizeStr)
 	var ok bool
-	size, ok = f.stdPageSizes[sizeStr]
+
+	//20210302 archium addendum begin
+	//enable custom page formats
+	if strings.Contains(sizeStr, "x") {
+		var (
+			aString []string
+			aFloat  []float64
+			aErr    error
+		)
+		aString = strings.Split(sizeStr, "x")
+		for i := 0; i <= 1; i++ {
+			aFloat[i], aErr = strconv.ParseFloat(aString[i], 64)
+			if aErr != nil {
+				f.err = fmt.Errorf("unknown page size %s", sizeStr)
+			}
+		}
+		size, ok = SizeType{aFloat[0], aFloat[1]}, true
+	} else {
+		//20210302 archium addendum end
+		size, ok = f.stdPageSizes[sizeStr]
+		//20210302 archium addendum begin
+	}
+	//20210302 archium addendum end
 	if ok {
 		// dbg("found %s", sizeStr)
 		size.Wd /= f.k