diff --git a/geokey/categories/migrations/0019_auto_20180626_0809.py b/geokey/categories/migrations/0019_auto_20180626_0809.py
new file mode 100644
index 00000000..1047fecd
--- /dev/null
+++ b/geokey/categories/migrations/0019_auto_20180626_0809.py
@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('categories', '0018_historicalcategory'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='category',
+            name='transparency',
+            field=models.IntegerField(default=100),
+        ),
+        migrations.AddField(
+            model_name='historicalcategory',
+            name='transparency',
+            field=models.IntegerField(default=100),
+        ),
+    ]
diff --git a/geokey/categories/models.py b/geokey/categories/models.py
index 325b07e2..196f0bf7 100644
--- a/geokey/categories/models.py
+++ b/geokey/categories/models.py
@@ -56,6 +56,7 @@ class Category(models.Model):
         max_length=20
     )
     colour = models.TextField(default='#0033ff')
+    transparency = models.IntegerField(default=100)
     symbol = models.ImageField(upload_to='symbols', null=True, max_length=500)
 
     objects = CategoryManager()
diff --git a/geokey/categories/views.py b/geokey/categories/views.py
index 63aa2c21..b272589c 100644
--- a/geokey/categories/views.py
+++ b/geokey/categories/views.py
@@ -258,6 +258,7 @@ def post(self, request, project_id, category_id):
         if category:
             symbol = request.FILES.get('symbol')
             category.colour = data.get('colour')
+            category.transparency = data.get('transparency')
 
             if symbol is not None:
                 category.symbol.delete()
diff --git a/geokey/templates/categories/category_display.html b/geokey/templates/categories/category_display.html
index fbd79234..8fb5e422 100644
--- a/geokey/templates/categories/category_display.html
+++ b/geokey/templates/categories/category_display.html
@@ -44,6 +44,13 @@ <h3 class="header">Category display</h3>
                     </div>
                 </div>
 
+                <div class="form-group">
+                    <label for="transparency" class="control-label">Transparency</label>
+                    <div class="input-group" id="transparency">
+                        <input type="text" name="transparency" value="{{ category.transparency }}" class="form-control" />
+                    </div>
+                </div>
+
                 <div class="form-group">
                     <label for="symbol" class="control-label">Symbol</label>
                     <input type="file" id="symbol" name="symbol" data-target="symbol" {% if category.symbol %}data-preview="{{ category.symbol.url }}"{% endif %} />