diff --git a/R/perc.R b/R/perc.R
new file mode 100644
index 0000000..b7ea5f7
--- /dev/null
+++ b/R/perc.R
@@ -0,0 +1,7 @@
+perc<-function(x, per100=T){
+  if (per100==T){
+    return(x*100/sum(x, na.rm = T))
+  }else{
+    return(x/sum(x, na.rm = T))
+  }
+}
\ No newline at end of file
diff --git a/man/perc.Rd b/man/perc.Rd
new file mode 100644
index 0000000..38419fe
--- /dev/null
+++ b/man/perc.Rd
@@ -0,0 +1,25 @@
+\name{perc}
+\alias{perc}
+\title{perc}
+\usage{
+perc(x, per100=T)
+}
+\arguments{
+  \item{x}{A numeric vector or an R object but not a factor coercible to numeric by as.double(x).}
+  \item{perc}{A logical value indicating whether the result must sum 100 (TRUE) or 1 (FALSE).}
+}
+\description{
+This function the percentages of a numeric vector.
+}
+\examples{
+v<-c(2,5,10,3)
+perc(v)
+
+# It can be used with dplyr tables
+library(tidyverse)
+df<-data.frame("X"=c("A","A","B","B"), "Y"=v)
+df \%>\% group_by(X) \%>\% summarise(Y=perc(Y))
+
+# Or it can be under 1
+df \%>\% group_by(X) \%>\% summarise(Y=perc(Y, per100=F))
+}