diff --git a/CHANGELOG.md b/CHANGELOG.md
index 932143a33c6..56e17a9eeb7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,6 @@
 ## [`master`](https://github.com/elastic/eui/tree/master)
 
+- Converted `pretty_interval` to TS ([#1920](https://github.com/elastic/eui/pull/1920))
 - Converted `relative_options` to TS ([#1921](https://github.com/elastic/eui/pull/1921))
 
 **Bug fixes**
diff --git a/src/components/date_picker/super_date_picker/pretty_interval.test.js b/src/components/date_picker/super_date_picker/pretty_interval.test.ts
similarity index 99%
rename from src/components/date_picker/super_date_picker/pretty_interval.test.js
rename to src/components/date_picker/super_date_picker/pretty_interval.test.ts
index 1eb067fdb92..e44138d3cf3 100644
--- a/src/components/date_picker/super_date_picker/pretty_interval.test.js
+++ b/src/components/date_picker/super_date_picker/pretty_interval.test.ts
@@ -1,4 +1,3 @@
-
 import { prettyInterval } from './pretty_interval';
 
 const IS_NOT_PAUSED = false;
diff --git a/src/components/date_picker/super_date_picker/pretty_interval.js b/src/components/date_picker/super_date_picker/pretty_interval.ts
similarity index 70%
rename from src/components/date_picker/super_date_picker/pretty_interval.js
rename to src/components/date_picker/super_date_picker/pretty_interval.ts
index fe8db73a50a..9530d7614e1 100644
--- a/src/components/date_picker/super_date_picker/pretty_interval.js
+++ b/src/components/date_picker/super_date_picker/pretty_interval.ts
@@ -1,27 +1,27 @@
-
 const MS_IN_SECOND = 1000;
 const MS_IN_MINUTE = 60 * MS_IN_SECOND;
 const MS_IN_HOUR = 60 * MS_IN_MINUTE;
 const MS_IN_DAY = 24 * MS_IN_HOUR;
 
-export function prettyInterval(isPaused, intervalInMs) {
+export const prettyInterval = (isPaused: boolean, intervalInMs: number) => {
+  let units: string;
   if (isPaused || intervalInMs === 0) {
     return 'Off';
   } else if (intervalInMs < MS_IN_MINUTE) {
     const intervalInSeconds = Math.round(intervalInMs / MS_IN_SECOND);
-    const units = intervalInSeconds > 1 ? 'seconds' : 'second';
+    units = intervalInSeconds > 1 ? 'seconds' : 'second';
     return `${intervalInSeconds} ${units}`;
   } else if (intervalInMs < MS_IN_HOUR) {
     const intervalInMinutes = Math.round(intervalInMs / MS_IN_MINUTE);
-    const units = intervalInMinutes > 1 ? 'minutes' : 'minute';
+    units = intervalInMinutes > 1 ? 'minutes' : 'minute';
     return `${intervalInMinutes} ${units}`;
   } else if (intervalInMs < MS_IN_DAY) {
     const intervalInHours = Math.round(intervalInMs / MS_IN_HOUR);
-    const units = intervalInHours > 1 ? 'hours' : 'hour';
+    units = intervalInHours > 1 ? 'hours' : 'hour';
     return `${intervalInHours} ${units}`;
   }
 
   const intervalInDays = Math.round(intervalInMs / MS_IN_DAY);
-  const units = intervalInDays > 1 ? 'days' : 'day';
+  units = intervalInDays > 1 ? 'days' : 'day';
   return `${intervalInDays} ${units}`;
-}
+};