diff --git a/packages/ui-default/components/contest/contest.page.styl b/packages/ui-default/components/contest/contest.page.styl
index 5d8b4e8d8..209109d00 100644
--- a/packages/ui-default/components/contest/contest.page.styl
+++ b/packages/ui-default/components/contest/contest.page.styl
@@ -41,6 +41,14 @@ for key, value in $contest-color
     background: $primary-color
     border-color: $primary-color
 
+.contest-timer
+  position: fixed;
+  left: 0;
+  top: 48px;
+  z-index: 10000;
+  +mobile()
+    visibility: hidden !important;
+
 .contest-problems
   font-size: 0.9375rem;
   font-weight: 400;
diff --git a/packages/ui-default/pages/contest.page.ts b/packages/ui-default/pages/contest.page.ts
index 956f9572e..954705d93 100644
--- a/packages/ui-default/pages/contest.page.ts
+++ b/packages/ui-default/pages/contest.page.ts
@@ -1,5 +1,10 @@
+import { formatSeconds } from '@hydrooj/utils/lib/common';
 import NProgress from 'nprogress';
 import { NamedPage } from 'vj/misc/Page';
+import tpl from 'vj/utils/tpl';
+
+const contestTimer = $(tpl`<pre class="contest-timer" style="display:none"></pre>`);
+contestTimer.appendTo(document.body);
 
 export default new NamedPage(['contest_detail', 'contest_detail_problem', 'contest_scoreboard'], () => {
   const beginAt = new Date(UiContext.tdoc.beginAt).getTime();
@@ -7,11 +12,17 @@ export default new NamedPage(['contest_detail', 'contest_detail_problem', 'conte
   NProgress.configure({ trickle: false, showSpinner: false, minimum: 0 });
   function updateProgress() {
     const now = Date.now();
-    if (beginAt <= now && now <= endAt) NProgress.set((now - beginAt) / (endAt - beginAt));
-    else if (now > endAt) NProgress.set(1);
-    else NProgress.set(0);
+    if (beginAt <= now && now <= endAt) {
+      NProgress.set((now - beginAt) / (endAt - beginAt));
+      contestTimer.show();
+      contestTimer.text(formatSeconds(Math.floor((endAt - now) / 1000)));
+    } else {
+      if (now > endAt) NProgress.set(1);
+      else NProgress.set(0);
+      contestTimer.hide();
+    }
   }
   NProgress.start();
   updateProgress();
-  setInterval(updateProgress, 5000);
+  setInterval(updateProgress, 1000);
 });
diff --git a/packages/utils/lib/common.ts b/packages/utils/lib/common.ts
index 0e6c9dc04..eaa9ef4b7 100644
--- a/packages/utils/lib/common.ts
+++ b/packages/utils/lib/common.ts
@@ -149,6 +149,20 @@ export function parseMemoryMB(str: string | number, throwOnError = true) {
     return Math.ceil(parseFloat(match[1]) * MEMORY_UNITS[match[2].toLowerCase()]);
 }
 
+function _digit2(number: number) {
+    return number < 10 ? `0${number}` : number.toString();
+}
+
+export function formatSeconds(_seconds: string | number = '0', showSeconds = true) {
+    const seconds = +_seconds;
+    let res = '{0}:{1}'.format(
+        showSeconds ? _digit2(Math.floor(seconds / 3600)) : Math.floor(seconds / 3600),
+        _digit2(Math.floor((seconds % 3600) / 60)),
+    );
+    if (showSeconds) res += `:${_digit2(seconds % 60)}`;
+    return res;
+}
+
 export function size(s: number, base = 1) {
     s *= base;
     const unit = 1024;
diff --git a/packages/utils/lib/utils.ts b/packages/utils/lib/utils.ts
index 6f4c1cedd..83cd47d43 100644
--- a/packages/utils/lib/utils.ts
+++ b/packages/utils/lib/utils.ts
@@ -190,20 +190,6 @@ export function errorMessage(err: Error | string) {
     return err;
 }
 
-function _digit2(number: number) {
-    return number < 10 ? `0${number}` : number.toString();
-}
-
-export function formatSeconds(_seconds: string | number = '0', showSeconds = true) {
-    const seconds = +_seconds;
-    let res = '{0}:{1}'.format(
-        showSeconds ? _digit2(Math.floor(seconds / 3600)) : Math.floor(seconds / 3600),
-        _digit2(Math.floor((seconds % 3600) / 60)),
-    );
-    if (showSeconds) res += `:${_digit2(seconds % 60)}`;
-    return res;
-}
-
 export function changeErrorType(err: any, Err: any) {
     const e = new Err(err.message);
     e.stack = err.stack;