diff --git a/reverse_proxy/nginx.conf b/reverse_proxy/nginx.conf
index ec48279..4a286ea 100644
--- a/reverse_proxy/nginx.conf
+++ b/reverse_proxy/nginx.conf
@@ -29,7 +29,8 @@ http {
     types_hash_max_size 2048;
     server_tokens off;
 
-    client_max_body_size 20m;
+    # See webserver/README.md to understand upload limits.
+    client_max_body_size 11M;
     client_body_timeout 60;
     client_body_buffer_size 128k;
 
diff --git a/webserver/README.md b/webserver/README.md
index 8036ce1..2893f0f 100644
--- a/webserver/README.md
+++ b/webserver/README.md
@@ -1,3 +1,27 @@
 # webserver
 
-This folder contains the resources necessary to build the RopeWiki webserver Docker image.
\ No newline at end of file
+This folder contains the resources necessary to build the RopeWiki webserver Docker image.
+
+
+## Upload limits
+There are 4 places which effect the upload limit, in order they are:
+ - reverse_proxy (nginx)
+ - webserver (nginx)
+ - php config
+ - mediawiki config
+
+### nginx
+Nginx will return a HTTP 413 error if `client_max_body_size` is exceed by an uploaded file.
+
+This is a "hard" error, and will likely give the user an ugly error page. Therefore it's
+important that this value is equal to or higher than the php/mediawiki value.
+
+Both the webserver & reverse_proxy need this value set. It's set at the global (http {...})
+level to avoid confusion around different paths getting different limits.
+
+### Mediawiki
+Mediawiki will pick whichever of these three is the lowest, and give a "soft" error before
+the upload begins:
+ - `upload_max_filesize` (php.ini)
+ - `post_max_size` (php.ini)
+ - `wgMaxUploadSize`, defaults to 100MB (LocalSettings.php)
diff --git a/webserver/html/ropewiki/LocalSettings.php b/webserver/html/ropewiki/LocalSettings.php
index a7da8ff..4954abf 100644
--- a/webserver/html/ropewiki/LocalSettings.php
+++ b/webserver/html/ropewiki/LocalSettings.php
@@ -259,7 +259,7 @@
 
 # ===================================================
 
-# Upload limits are set in php.ini (upload_max_filesize)
+# See README.md to understand upload limits.
 #$wgUploadSizeWarning = 5242880;
 #$wgMaxUploadSize = 5242880;
 
diff --git a/webserver/nginx/nginx.conf b/webserver/nginx/nginx.conf
index ec33249..ca28d90 100644
--- a/webserver/nginx/nginx.conf
+++ b/webserver/nginx/nginx.conf
@@ -25,7 +25,8 @@ http {
     include /etc/nginx/mime.types;
     default_type application/octet-stream;
 
-    client_max_body_size 20m;
+    # See webserver/README.md to understand upload limits.
+    client_max_body_size 11M;
     client_body_buffer_size 128k;
 
     access_log /var/log/nginx/access.log;
diff --git a/webserver/nginx/sites-enabled/ropewiki.com b/webserver/nginx/sites-enabled/ropewiki.com
index 0814863..7764562 100644
--- a/webserver/nginx/sites-enabled/ropewiki.com
+++ b/webserver/nginx/sites-enabled/ropewiki.com
@@ -3,8 +3,7 @@
 server {
     listen 80 default_server;
     listen [::]:80 default_server ipv6only=on;
-        #add_header Access-Control-Allow-Origin www.ropewiki.com;
-        client_max_body_size 5M;
+    #add_header Access-Control-Allow-Origin www.ropewiki.com;
     root /usr/share/nginx/html/ropewiki;
     index index.php index.html index.htm;