diff --git a/cara/apps/calculator/static/js/form.js b/cara/apps/calculator/static/js/form.js
index 8d63b7b1..ef5f29d8 100644
--- a/cara/apps/calculator/static/js/form.js
+++ b/cara/apps/calculator/static/js/form.js
@@ -109,7 +109,6 @@ function require_mechanical_ventilation(option) {
 function require_natural_ventilation(option) {
   $("#windows_number").prop('required', option);
   $("#window_height").prop('required', option);
-  $("#window_width").prop('required', option);
   $("#opening_distance").prop('required', option);
   $("#always").prop('required', option);
   $("#interval").prop('required', option);
diff --git a/cara/apps/calculator/templates/calculator.form.html.j2 b/cara/apps/calculator/templates/calculator.form.html.j2
index 8e5d068b..f3247cfd 100644
--- a/cara/apps/calculator/templates/calculator.form.html.j2
+++ b/cara/apps/calculator/templates/calculator.form.html.j2
@@ -61,7 +61,6 @@
     <div id="DIVnatural_ventilation" style="display:none">
         Number of windows: <input type="number" id="windows_number" name="windows_number" min="1"><br>
         Height of window: <input type="number" step=0.01 id="window_height" name="window_height" placeholder="meters" min="0"><br>
-        Width of window: <input type="number" step=0.01 id="window_width"  name="window_width" placeholder="meters" min="0"><br>
         Opening distance: <input type="number" step=0.01 id="opening_distance"  name="opening_distance" placeholder="meters" min="0"><br>
         Windows open: <input type="radio" id="always" name="windows_open" value="always">
                       <label for="always">Always</label>