diff --git a/variables.tf b/variables.tf
index 8f82166..3a78330 100644
--- a/variables.tf
+++ b/variables.tf
@@ -41,3 +41,21 @@ variable "ingress_cidr" {
   default     = "172.59.221.135/32"
 }
 
+variable "instance_type" {
+  description = "Instance Type"
+  default     = "t2.micro"
+  validation {
+          condition     = ( 
+            var.instance_type == "t2.micro"   ||
+            var.instance_type == "t3.medium"  ||
+            var.instance_type == "m5.large"   ||
+            var.instance_type == "c5.large"   ||
+            var.instance_type == "c5a.large"  ||
+            var.instance_type == "m5.2xlarge" ||
+            var.instance_type == "c5.2xlarge" ||
+            var.instance_type == "m5.4xlarge" ||
+            var.instance_type == "c5.4xlarge"
+          )
+          error_message = "Instance_type must be set to a valid vm instance type."
+      }
+}
\ No newline at end of file