diff --git a/sd_card_speed_test.sh b/sd_card_speed_test.sh
new file mode 100644
index 0000000..78fcde1
--- /dev/null
+++ b/sd_card_speed_test.sh
@@ -0,0 +1,59 @@
+#!/bin/bash
+# Created by Alexander aka BioDranik <me@alex.bio> in Minsk, Belarus
+
+set -eu
+
+if [ $# -lt 1 ]; then
+  echo "Usage: $0 <path_to_directory_where_to_test_read_and_write_speed>"
+  exit 1
+fi
+
+SD_DIR=$1
+FILENAME="$SD_DIR/file_speed_test.deleteme"
+SIZE=1000 # in MB
+
+if [[ "$OSTYPE" == "darwin"* ]]; then
+  WRITE_FILE_COMMAND="mkfile ${SIZE}m $FILENAME"
+  CLEAR_CACHE_COMMAND="purge"
+else
+  WRITE_FILE_COMMAND="dd if=/dev/zero of=$FILENAME bs=1M count=$SIZE oflag=direct"
+  CLEAR_CACHE_COMMAND='sh -c echo 3 > /proc/sys/vm/drop_caches'
+fi
+READ_FILE_COMMAND="cat $FILENAME > /dev/null"
+
+RunTimeInSeconds() {
+  local TIMEFORMAT=%R
+  RES=`{ time $@ >/dev/null 2>&1; } 2>&1`
+  echo $RES
+}
+
+ClearFileCache() {
+  if sudo -n false 2>/dev/null; then
+    echo "Administrator password is required to clear file cache and get correct read test results."
+  fi
+  sudo $CLEAR_CACHE_COMMAND
+}
+
+WriteFile() {
+  echo "Writing ${SIZE}MB file $FILENAME..."
+  local WRITE_SECONDS=`RunTimeInSeconds $WRITE_FILE_COMMAND`
+  if [ -f "$FILENAME" ]; then
+    local WRITE_SPEED=$( echo "scale=2; $SIZE/$WRITE_SECONDS" | bc -l)
+    echo "Average sequential write speed: ${WRITE_SPEED}MB/sec."
+  else
+    echo "Error writing file $FILENAME"
+    false
+  fi
+}
+
+ReadFile() {
+  local READ_SECONDS=`RunTimeInSeconds $READ_FILE_COMMAND`
+  local READ_SPEED=$( echo "scale=2; $SIZE/$READ_SECONDS" | bc -l)
+  echo "Average sequential read speed: ${READ_SPEED}MB/sec."
+}
+
+WriteFile
+# Always delete created file on exit.
+trap "rm $FILENAME" 0
+ClearFileCache
+ReadFile