diff --git a/src/diagnostic/entitycount.js b/src/diagnostic/entitycount.js
new file mode 100644
index 00000000..4520c7e1
--- /dev/null
+++ b/src/diagnostic/entitycount.js
@@ -0,0 +1,42 @@
+import { App, AppSchedule } from '../app/index.js'
+import { World, Entity, Query } from '../ecs/index.js'
+
+export class EntityCountDiagnosticPlugin {
+  
+  /**
+   * @param {App} app
+   */
+  register(app) {
+    app
+      .registerSystem(AppSchedule.Startup, setUpUI)
+      .registerSystem(AppSchedule.Update, updateEntityCount)
+  }
+}
+
+/**
+ *
+ */
+function setUpUI() {
+  const container = document.body.appendChild(document.createElement('div'))
+  
+  container.id = 'entity-count-container'
+  container.style.position = 'absolute'
+  container.style.top = '34px'
+  container.style.right = '0px'
+  container.style.width = '100px'
+  container.style.height = '20px'
+  container.style.background = 'black'
+  container.style.textAlign = 'center'
+  container.style.color = 'white'
+}
+
+/**
+ * @param {World} world
+ */
+function updateEntityCount(world) {
+  const entities = new Query(world, [Entity])
+  const num = entities.count()
+  const container = document.querySelector('#entity-count-container')
+  
+  if (container) container.innerHTML = `${num} entities`
+}
\ No newline at end of file
diff --git a/src/diagnostic/index.js b/src/diagnostic/index.js
index 1064546b..2b3c58ee 100644
--- a/src/diagnostic/index.js
+++ b/src/diagnostic/index.js
@@ -1 +1,2 @@
-export * from './fpsdebugger.js'
\ No newline at end of file
+export * from './fpsdebugger.js'
+export * from '././entitycount.js'
\ No newline at end of file