diff --git a/static/v3/dashboard.js b/static/v3/dashboard.js
index 5123535..59e5e7e 100644
--- a/static/v3/dashboard.js
+++ b/static/v3/dashboard.js
@@ -33,7 +33,8 @@
     // Accuracy badge ramp (design/04-badges.md §C): ≥90% good, 50–89% mid, <50% low.
     function accuracyBadge(acc) {
         if (acc == null) return '';
-        const pct = Math.round(acc * 100);
+        // Floor, never round: 100% must mean every note hit.
+        const pct = Math.floor(acc * 100);
         const color = acc >= 0.9 ? 'bg-fb-good' : (acc >= 0.5 ? 'bg-fb-mid' : 'bg-fb-low');
         const text = acc >= 0.5 && acc < 0.9 ? 'text-black' : 'text-white';
         return '<span class="absolute bottom-0 right-0 ' + color + '/90 ' + text +
diff --git a/static/v3/lessons.js b/static/v3/lessons.js
index c835326..aa333cf 100644
--- a/static/v3/lessons.js
+++ b/static/v3/lessons.js
@@ -74,7 +74,7 @@
         if (st && st.passed) return '<span class="text-fb-good text-xs font-bold flex items-center gap-1">✓ Passed</span>';
         if (st && st.best_accuracy != null && st.best_accuracy > 0) {
             const acc = st.best_accuracy;
-            const pct = Math.round(acc * 100);
+            const pct = Math.floor(acc * 100);
             const color = acc >= 0.9 ? 'text-fb-good' : (acc >= 0.5 ? 'text-fb-mid' : 'text-fb-low');
             return '<span class="' + color + ' text-xs font-bold">' + pct + '%</span>';
         }
diff --git a/static/v3/live-performance-hud.js b/static/v3/live-performance-hud.js
index 32b47ed..37d8512 100644
--- a/static/v3/live-performance-hud.js
+++ b/static/v3/live-performance-hud.js
@@ -21,7 +21,8 @@
     function accuracyPct(hits, misses) {
         const judged = hits + misses;
         if (judged <= 0) return null;
-        return Math.round((hits / Math.max(1, judged)) * 100);
+        // Floor, never round: 100% must mean every judged note was hit.
+        return Math.floor((hits / Math.max(1, judged)) * 100);
     }
 
     function calculateLivePerformanceState({ hits = 0, misses = 0, streak = 0, bestStreak = 0 } = {}) {
diff --git a/static/v3/playlists.js b/static/v3/playlists.js
index 2efff61..7684344 100644
--- a/static/v3/playlists.js
+++ b/static/v3/playlists.js
@@ -73,7 +73,7 @@
             ? ' data-play-fn="' + esc(playFn) + '"' + (arrIdx != null ? ' data-play-arr="' + arrIdx + '"' : '')
             : '';
         const acc = (isAlbum && typeof opts.acc === 'number')
-            ? '<span class="text-xs font-bold shrink-0 ' + (opts.acc >= 0.9 ? 'text-fb-good' : opts.acc >= 0.5 ? 'text-fb-mid' : 'text-fb-low') + '">' + Math.round(opts.acc * 100) + '%</span>'
+            ? '<span class="text-xs font-bold shrink-0 ' + (opts.acc >= 0.9 ? 'text-fb-good' : opts.acc >= 0.5 ? 'text-fb-mid' : 'text-fb-low') + '">' + Math.floor(opts.acc * 100) + '%</span>'
             : '';
         const pin = (isAlbum && s.arrangement)
             ? '<span class="ml-2 text-[0.625rem] bg-fb-primary/20 text-fb-primary font-bold px-1.5 py-0.5 rounded-sm" title="Pinned arrangement">' + esc(s.arrangement) + '</span>' : '';
diff --git a/static/v3/profile.js b/static/v3/profile.js
index 71f7cb9..ce79818 100644
--- a/static/v3/profile.js
+++ b/static/v3/profile.js
@@ -232,7 +232,7 @@
         host.innerHTML =
             '<ol class="space-y-2">' + rows.map((s, i) => {
                 const acc = Number(s.best_accuracy) || 0;
-                const pct = Math.round(acc * 100);
+                const pct = Math.floor(acc * 100);
                 const score = Number(s.best_score) || 0;
                 return '<li data-fn="' + esc(s.filename) + '" class="flex items-center gap-3 cursor-pointer rounded-md px-2 py-1.5 hover:bg-fb-card transition">' +
                     '<span class="w-5 text-center text-fb-textDim font-semibold shrink-0">' + (i + 1) + '</span>' +
diff --git a/static/v3/progress.js b/static/v3/progress.js
index 5867449..018775c 100644
--- a/static/v3/progress.js
+++ b/static/v3/progress.js
@@ -265,7 +265,7 @@
         const onboarding = st.onboarding || {};
         if (onboarding.calibration_status === 'completed') return; // raced a 100% run
         const pending = onboarding.calibration_status === 'pending';
-        const pct = Math.max(0, Math.min(100, Math.round((detail.accuracy || 0) * 100)));
+        const pct = Math.max(0, Math.min(100, Math.floor((detail.accuracy || 0) * 100)));
 
         const overlay = document.createElement('div');
         overlay.id = 'v3-calibration-retry';
diff --git a/static/v3/songs.js b/static/v3/songs.js
index a05536c..255e814 100644
--- a/static/v3/songs.js
+++ b/static/v3/songs.js
@@ -482,7 +482,8 @@
     function accuracyBadge(filename, variant) {
         const acc = state.accuracy[filename];
         if (acc == null) return '';
-        const pct = Math.round(acc * 100);
+        // Floor, never round: 100% must mean every note hit.
+        const pct = Math.floor(acc * 100);
         if (variant === 'tree') {
             const color = acc >= MASTERY_ACCURACY ? 'text-fb-good' : acc >= 0.5 ? 'text-fb-mid' : 'text-fb-low';
             return '<span class="fb-acc-badge text-xs font-bold ' + color + '">' + pct + '%</span>';
@@ -1312,7 +1313,7 @@
             c.year ? String(c.year) : '']
             .filter(Boolean).join(' · ');
         const acc = (typeof c.best_accuracy === 'number')
-            ? '<span class="font-bold ' + (c.best_accuracy >= MASTERY_ACCURACY ? 'text-fb-good' : c.best_accuracy >= 0.5 ? 'text-fb-mid' : 'text-fb-low') + '">' + Math.round(c.best_accuracy * 100) + '%</span>'
+            ? '<span class="font-bold ' + (c.best_accuracy >= MASTERY_ACCURACY ? 'text-fb-good' : c.best_accuracy >= 0.5 ? 'text-fb-mid' : 'text-fb-low') + '">' + Math.floor(c.best_accuracy * 100) + '%</span>'
             : '<span class="text-fb-textDim/60">not played</span>';
         return '<div role="radio" aria-checked="' + (checked ? 'true' : 'false') + '" tabindex="0" data-ch="' + esc(c.filename) + '"' +
             ' title="' + (checked ? esc(prefLabel) : 'Make this the preferred chart') + '"' +
diff --git a/tests/js/live_performance_hud.test.js b/tests/js/live_performance_hud.test.js
index c22ebd5..674c306 100644
--- a/tests/js/live_performance_hud.test.js
+++ b/tests/js/live_performance_hud.test.js
@@ -170,7 +170,8 @@ test('DOM text updates after hit and miss events', () => {
     runtime.onHit();
     runtime.onMiss();
 
-    assert.equal(els.percent.textContent, '67%');
+    // Floored, not rounded: 100% must mean every judged note was hit.
+    assert.equal(els.percent.textContent, '66%');
     assert.equal(els.hits.textContent, 'Hits 2 / 3');
     assert.equal(els.streak.textContent, 'Streak 0');
     assert.match(els.state.textContent, /Recovering/);