diff --git a/NAMESPACE b/NAMESPACE
index ea061d904..359b391ce 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -15,6 +15,7 @@ S3method(bind_into_vpts,list)
 S3method(bind_into_vpts,vp)
 S3method(bind_into_vpts,vpts)
 S3method(c,vp)
+S3method(calculate_param,ppi)
 S3method(calculate_param,pvol)
 S3method(calculate_param,scan)
 S3method(check_night,default)
diff --git a/NEWS.md b/NEWS.md
index e5ca026b6..03d355bbd 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,7 @@
 # bioRad 0.5.2.9XXX
 
+* `calculate_param()` now also works on ppi's (#316)
+
 * Speed up `integrate_to_ppi` and other functions by avoiding duplicate input argument checking (#358)
 
 * Warn when multiple scans with the same elevation are equally close to the requested elevation in `get_scan()`, and add option to return all (#414)
diff --git a/R/calculate_param.R b/R/calculate_param.R
index 40a7438dc..a85baeb7e 100644
--- a/R/calculate_param.R
+++ b/R/calculate_param.R
@@ -14,6 +14,7 @@
 #'
 #' # load the file:
 #' example_pvol <- read_pvolfile(pvolfile)
+#' data(example_scan)
 #'
 #' # calculate linear reflectivity ETA from reflectivity factor DBZH:
 #' radar_wavelength <- example_pvol$attributes$how$wavelength
@@ -26,6 +27,11 @@
 #' # calculate_param operates on both pvol and scan objects:
 #' calculate_param(example_scan, DR = 10 * log10((ZDR + 1 - 2 * ZDR^0.5 * RHOHV) /
 #'   (ZDR + 1 + 2 * ZDR^0.5 * RHOHV)))
+#'
+#' # it also works for ppis
+#' ppi <- project_as_ppi(example_scan)
+#' calculate_param(ppi, exp(DBZH))
+#'
 #' @references
 #' \itemize{
 #'   \item Kilambi, A., Fabry, F., and Meunier, V., 2018. A simple and effective method
@@ -40,15 +46,34 @@ calculate_param <- function(x, ...) {
 #' @describeIn calculate_param Calculate a new scan parameter for all scans in a polar volume.
 #' @export
 calculate_param.pvol <- function(x, ...) {
-  assert_that(class(x) == "pvol")
+  assert_that(is.pvol(x))
   x$scans <- do.call(lapply, list(x$scans, calculate_param.scan, substitute(list(...))))
   return(x)
 }
 
+#' @describeIn calculate_param Calculate a new parameter for a PPI.
+#' @export
+calculate_param.ppi <- function(x, ...) {
+  assert_that(is.ppi(x))
+  calc <- as.list(substitute(list(...)))[-1L]
+  name <- names(calc)
+  if (is.null(name)) {
+    name <- rep("", length(calc))
+  }
+  for (i in seq_along(calc)) {
+    newParam <- eval(nn <- (calc[[i]]), x$data@data)
+    if ("" == (name[[i]])) {
+      name[[i]] <- deparse(nn, width.cutoff = 250L)[1]
+    }
+    x$data@data[,name[[i]]]<-newParam
+  }
+  return(x)
+}
+
 #' @describeIn calculate_param Calculate a new scan parameter for a scan
 #' @export
 calculate_param.scan <- function(x, ...) {
-  assert_that(class(x) == "scan")
+  assert_that(is.scan(x))
   # check if all parameters are equal
   attr_to_check<-c('class','radar','datetime','geo','dim')
   for(i in attr_to_check){
diff --git a/man/calculate_param.Rd b/man/calculate_param.Rd
index 55244d033..bc61ccf80 100644
--- a/man/calculate_param.Rd
+++ b/man/calculate_param.Rd
@@ -3,6 +3,7 @@
 \name{calculate_param}
 \alias{calculate_param}
 \alias{calculate_param.pvol}
+\alias{calculate_param.ppi}
 \alias{calculate_param.scan}
 \title{Calculate a new scan parameter}
 \usage{
@@ -10,6 +11,8 @@ calculate_param(x, ...)
 
 \method{calculate_param}{pvol}(x, ...)
 
+\method{calculate_param}{ppi}(x, ...)
+
 \method{calculate_param}{scan}(x, ...)
 }
 \arguments{
@@ -30,6 +33,8 @@ clutter corrections (CCORH) to uncorrected reflectivity moments (TH), as in TH+C
 \itemize{
 \item \code{pvol}: Calculate a new scan parameter for all scans in a polar volume.
 
+\item \code{ppi}: Calculate a new parameter for a PPI.
+
 \item \code{scan}: Calculate a new scan parameter for a scan
 }}
 
@@ -39,6 +44,7 @@ pvolfile <- system.file("extdata", "volume.h5", package = "bioRad")
 
 # load the file:
 example_pvol <- read_pvolfile(pvolfile)
+data(example_scan)
 
 # calculate linear reflectivity ETA from reflectivity factor DBZH:
 radar_wavelength <- example_pvol$attributes$how$wavelength
@@ -51,6 +57,11 @@ example_pvol <- calculate_param(example_pvol, DR = 10 * log10((ZDR + 1 - 2 * ZDR
 # calculate_param operates on both pvol and scan objects:
 calculate_param(example_scan, DR = 10 * log10((ZDR + 1 - 2 * ZDR^0.5 * RHOHV) /
   (ZDR + 1 + 2 * ZDR^0.5 * RHOHV)))
+
+# it also works for ppis
+ppi <- project_as_ppi(example_scan)
+calculate_param(ppi, exp(DBZH))
+
 }
 \references{
 \itemize{
diff --git a/man/calculate_vp.Rd b/man/calculate_vp.Rd
index a5107eb73..589b620cb 100644
--- a/man/calculate_vp.Rd
+++ b/man/calculate_vp.Rd
@@ -22,7 +22,7 @@ calculate_vp(
   azim_max = 360,
   range_min = 5000,
   range_max = 35000,
-  n_layer = 20L,
+  n_layer = 20,
   h_layer = 200,
   dealias = TRUE,
   nyquist_min = if (dealias) 5 else 25,
diff --git a/man/sub-.ppi.Rd b/man/sub-.ppi.Rd
index 8ac3e64fa..ea712b2e2 100644
--- a/man/sub-.ppi.Rd
+++ b/man/sub-.ppi.Rd
@@ -23,13 +23,13 @@ position indicator (\code{ppi}).
 # Project a scan as a ppi
 ppi <- project_as_ppi(example_scan)
 
-# This ppi contains 5 parameters (VRADH DBZH ZDR RHOHV PHIDP)
+# This ppi contains 5 parameters (DBZH VRADH ZDR RHOHV PHIDP)
 ppi
 
-# Subset ppi to one containing only the first parameter (VRADH)
+# Subset ppi to one containing only the first parameter (DBZH)
 ppi[1]
 
-# Subset ppi to one containing the first three parameters (VRADH, DBZH, ZDR)
+# Subset ppi to one containing the first three parameters (DBZH, VRADH, ZDR)
 ppi[1:3]
 
 # Subset ppi to one without the first 2 parameters (ZDR RHOHV PHIDP)