diff --git a/bin/tempscale b/bin/tempscale
index a057a1f..3114d17 100755
Binary files a/bin/tempscale and b/bin/tempscale differ
diff --git a/src/main.c b/src/main.c
index 0283741..1223825 100644
--- a/src/main.c
+++ b/src/main.c
@@ -7,6 +7,7 @@
 #include "scales/celsius_option.h"
 #include "scales/fahrenheit_option.h"
 #include "scales/kelvin_option.h"
+#include "scales/rankine_option.h"
 #include <stdio.h>
 
 int main(void) {
@@ -56,6 +57,10 @@ int main(void) {
       invalid_option = 0;
       kelvin_option();
       continue;
+    } else if (option == 4) {
+      invalid_option = 0;
+      rankine_option();
+      continue;
     };
 
     break;
diff --git a/src/scales/rankine_description.c b/src/scales/rankine_description.c
new file mode 100644
index 0000000..4653e85
--- /dev/null
+++ b/src/scales/rankine_description.c
@@ -0,0 +1,17 @@
+#include "../displays/ansi_color_codes.h"
+#include "../displays/clear_screen.h"
+#include "../displays/escape_sequence.h"
+
+void rankine_description(void) {
+  add_new_tab();
+  printf("%s--------------------------------------------------%s", BLUE, RESET);
+  add_new_line();
+  add_new_line();
+  add_new_tab();
+  add_new_tab();
+  printf("    %sRankine (°R) to Other Scale%s", GREEN, RESET);
+  add_new_line();
+  add_new_line();
+  add_new_tab();
+  printf("%s--------------------------------------------------%s", BLUE, RESET);
+}
diff --git a/src/scales/rankine_description.h b/src/scales/rankine_description.h
new file mode 100644
index 0000000..14d004f
--- /dev/null
+++ b/src/scales/rankine_description.h
@@ -0,0 +1,7 @@
+#ifndef RANKINE_DESCRIPTION_H
+#define RANKINE_DESCRIPTION_H
+#include "rankine_description.c"
+
+extern void rankine_description(void);
+
+#endif
diff --git a/src/scales/rankine_option.c b/src/scales/rankine_option.c
new file mode 100644
index 0000000..76a4eaa
--- /dev/null
+++ b/src/scales/rankine_option.c
@@ -0,0 +1,86 @@
+#include "../displays/ansi_color_codes.h"
+#include "../displays/clear_screen.h"
+#include "../displays/escape_sequence.h"
+#include "check_valid_input.h"
+#include "rankine_description.h"
+
+void rankine_option(void) {
+  char *rankine_string = malloc(sizeof(char) * 50);
+  int invalid_input = 0;
+  char *garbage_buffer = malloc(sizeof(char) * 50);
+  int try_again = 0;
+
+  while (1) {
+    // Clean up the terminal.
+    clear_screen();
+    add_new_line();
+    add_new_line();
+
+    // Display the option description.
+    rankine_description();
+    add_new_line();
+    add_new_line();
+
+    // Display the error message.
+    if (invalid_input) {
+      add_new_tab();
+      printf(" %sInvalid input. Please try again.%s", RED, RESET);
+      add_new_line();
+      add_new_line();
+    }
+
+    // Ask the input.
+    add_new_tab();
+    printf(" Rankine (°R)         : ");
+    scanf("%s", rankine_string);
+    fgets(garbage_buffer, 50, stdin);
+
+    // Check if input is valid.
+    int valid_input = check_valid_input(rankine_string);
+    if (valid_input == 0) {
+      invalid_input = 1;
+      continue;
+    } else {
+      invalid_input = 0;
+    }
+
+    // Convert the rankine string input to double.
+    double rankine_double = atof(rankine_string);
+
+    // Handle computation for celsius scale.
+    double celsius = (rankine_double - 491.67) * (5.0 / 9.0);
+    add_new_tab();
+    printf(" %sCelsius (°C)%s         : %s%.4lf (°C)%s ", BLUE, RESET, YELLOW,
+           celsius, RESET);
+    add_new_line();
+
+    // Handle computation for fahrenheit scale.
+    double fahrenheit = rankine_double - 459.67;
+    add_new_tab();
+    printf(" %sFahrenheit (°F)%s      : %s%.4lf (°F)%s", BLUE, RESET, YELLOW,
+           fahrenheit, RESET);
+    add_new_line();
+
+    // Handle computation for kelvin scale.
+    double kelvin = rankine_double * (5.0 / 9.0);
+    add_new_tab();
+    printf(" %sKelvin (°K)%s          : %s%.4lf (°K)%s", BLUE, RESET, YELLOW,
+           kelvin, RESET);
+    add_new_line();
+    add_new_line();
+
+    // Ask user if want to try again.
+    add_new_tab();
+    printf(" Try again (1-yes, 0-no): ");
+    scanf("%d", &try_again);
+    fgets(garbage_buffer, 50, stdin);
+
+    // Handle the input of user.
+    if (try_again == 1) {
+      invalid_input = 0;
+      continue;
+    } else {
+      break;
+    }
+  }
+}
diff --git a/src/scales/rankine_option.h b/src/scales/rankine_option.h
new file mode 100644
index 0000000..7b542eb
--- /dev/null
+++ b/src/scales/rankine_option.h
@@ -0,0 +1,7 @@
+#ifndef RANKINE_OPTION_H
+#define RANKINE_OPTION_H
+#include "rankine_option.c"
+
+extern void rankine_option(void);
+
+#endif