diff --git a/src/custom-expressions.ts b/src/custom-expressions.ts
index 257a4d5..4de5ffb 100644
--- a/src/custom-expressions.ts
+++ b/src/custom-expressions.ts
@@ -440,3 +440,43 @@ export async function loadFollowupStatus(patient) {
   }
   return status?.valueCodeableConcept?.coding[0]?.code;
 }
+
+export async function getAgeFromBirthdate(dateOfBirth) {
+  if (dateOfBirth) {
+    const birthdate = new Date(dateOfBirth);
+    const today = new Date();
+    let age = today.getFullYear() - birthdate.getFullYear();
+    const monthDifference = today.getMonth() - birthdate.getMonth();
+    if (
+      monthDifference < 0 ||
+      (monthDifference === 0 && today.getDate() < birthdate.getDate())
+    ) {
+      age--;
+    }
+    return age;
+  } else {
+    return null;
+  }
+}
+
+export async function getBirthdateFromAge(contactAge) {
+  if (contactAge) {
+    const today = new Date();
+    const birthYear = today.getFullYear() - contactAge;
+    const birthdate = new Date(today.setFullYear(birthYear));
+    const options: Intl.DateTimeFormatOptions = {
+      weekday: "short",
+      year: "numeric",
+      month: "short",
+      day: "2-digit",
+      timeZoneName: "short",
+    };
+    return (
+      birthdate.toLocaleDateString("en-US", options) +
+      " " +
+      birthdate.toTimeString().split(" ")[0]
+    );
+  } else {
+    return null;
+  }
+}
diff --git a/src/forms/index-contact-followup.json b/src/forms/index-contact-followup.json
index 3a007d9..a22d923 100644
--- a/src/forms/index-contact-followup.json
+++ b/src/forms/index-contact-followup.json
@@ -169,6 +169,9 @@
                         "id": "contactAge",
                         "questionOptions": {
                           "rendering": "number",
+                          "calculate": {
+                            "calculateExpression": "getAgeFromBirthdate('dateOfBirth')"
+                            },
                           "concept": "1532AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
                           "max": 200,
                           "min": 0,
@@ -181,6 +184,19 @@
                           ]
                       }
                     },
+                    {
+                        "label": "Date of Birth",
+                        "type": "obs",
+                        "required": false,
+                        "id": "dateOfBirth",
+                        "questionOptions": {
+                          "rendering": "date",
+                          "calculate": {
+                            "calculateExpression": "getBirthdateFromAge('contactAge')"
+                            },
+                          "concept": "e27ae70c-6131-4004-9da8-841619e19480"
+                        }
+                    },
                     {
                         "label": "Sex",
                         "type": "obs",
diff --git a/src/index.ts b/src/index.ts
index 5069365..29d253a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -43,6 +43,8 @@ import {
   isSupplementaryFoodVisible,
   isTreatmentVisible,
   loadFollowupStatus,
+  getBirthdateFromAge,
+  getAgeFromBirthdate
 } from "./custom-expressions";
 import {
   createConditionalDashboardGroup,
@@ -104,6 +106,8 @@ export function startupApp() {
     isSupplementaryFoodVisible
   );
   registerExpressionHelper("loadFollowupStatus", loadFollowupStatus);
+  registerExpressionHelper("getBirthdateFromAge", getBirthdateFromAge);
+  registerExpressionHelper("getAgeFromBirthdate", getAgeFromBirthdate);
   // registerControl({
   //   name: "eth-date",
   //   load: () => import("./components/controls/date/ethiohri-date.component"),