diff --git a/src/Survey/AreaCount/Area/NewLocationModal/config.tsx b/src/Survey/AreaCount/Area/NewLocationModal/config.tsx
index 41c23f9e..d4e499e9 100644
--- a/src/Survey/AreaCount/Area/NewLocationModal/config.tsx
+++ b/src/Survey/AreaCount/Area/NewLocationModal/config.tsx
@@ -5,6 +5,8 @@ export const siteNameAttr = {
   container: 'inline',
 } as const;
 
+export const OTHER_SITE_SIZE_VALUE = '23733';
+
 export const siteAreaAttr = {
   id: 'locAttr:376',
   type: 'choice_input',
@@ -15,7 +17,7 @@ export const siteAreaAttr = {
     { title: '20 x 25 m', data_name: '23730' },
     { title: '10 x 50 m', data_name: '23731' },
     { title: '5 x 100 m', data_name: '23732' },
-    { title: 'other', data_name: '23733' },
+    { title: 'other', data_name: OTHER_SITE_SIZE_VALUE },
   ],
 } as const;
 
@@ -59,6 +61,16 @@ export const grainsNumberAttr = {
   validations: { min: 0, max: 100 },
 } as const;
 
+export const customAreaSizeAttr = {
+  id: 'locAttr:159',
+  type: 'number_input',
+  title: 'Area size',
+  appearance: 'counter',
+  placeholder: '0',
+  suffix: 'm²',
+  validations: { min: 0 },
+} as const;
+
 export const vegetablesNumberAttr = {
   id: 'locAttr:342',
   type: 'number_input',
diff --git a/src/Survey/AreaCount/Area/NewLocationModal/index.tsx b/src/Survey/AreaCount/Area/NewLocationModal/index.tsx
index be9a6161..df80d024 100644
--- a/src/Survey/AreaCount/Area/NewLocationModal/index.tsx
+++ b/src/Survey/AreaCount/Area/NewLocationModal/index.tsx
@@ -29,10 +29,12 @@ import Media from 'common/models/media';
 import { Group } from 'common/models/sample';
 import HeaderButton from 'Survey/common/HeaderButton';
 import {
+  OTHER_SITE_SIZE_VALUE,
   buildingsNumberAttr,
   commentAttr,
   cornNumberAttr,
   croppingNumberAttr,
+  customAreaSizeAttr,
   fallowNumberAttr,
   fertilizedAttr,
   forestNumberAttr,
@@ -195,6 +197,9 @@ const NewLocationModal = (
     },
   });
 
+  const isOtherSiteSize =
+    (newLocation as any)[siteAreaAttr.id] === OTHER_SITE_SIZE_VALUE;
+
   return (
     <>
       <IonModal
@@ -238,6 +243,9 @@ const NewLocationModal = (
                 isUNPplus) && (
                 <>
                   <Block {...getBlockAttrs(siteAreaAttr)} />
+                  {isOtherSiteSize && (
+                    <Block {...getBlockAttrs(customAreaSizeAttr)} />
+                  )}
                   <InfoMessage inline>
                     Approximate size of your observation site.
                   </InfoMessage>