diff --git a/lighthouse-core/report/html/renderer/category-renderer.js b/lighthouse-core/report/html/renderer/category-renderer.js
index 5b4b7b0c21a2..f455b9b2de46 100644
--- a/lighthouse-core/report/html/renderer/category-renderer.js
+++ b/lighthouse-core/report/html/renderer/category-renderer.js
@@ -159,13 +159,14 @@ class CategoryRenderer {
 
   /**
    * @param {LH.ReportResult.Category} category
+   * @param {Record<string, LH.Result.ReportGroup>} groupDefinitions
    * @return {Element}
    */
-  renderCategoryHeader(category) {
+  renderCategoryHeader(category, groupDefinitions) {
     const tmpl = this.dom.cloneTemplate('#tmpl-lh-category-header', this.templateContext);
 
     const gaugeContainerEl = this.dom.find('.lh-score__gauge', tmpl);
-    const gaugeEl = this.renderScoreGauge(category);
+    const gaugeEl = this.renderScoreGauge(category, groupDefinitions);
     gaugeContainerEl.appendChild(gaugeEl);
 
     this.dom.find('.lh-category-header__title', tmpl).appendChild(
@@ -329,9 +330,10 @@ class CategoryRenderer {
 
   /**
    * @param {LH.ReportResult.Category} category
+   * @param {Record<string, LH.Result.ReportGroup>} groupDefinitions
    * @return {DocumentFragment}
    */
-  renderScoreGauge(category) {
+  renderScoreGauge(category, groupDefinitions) { // eslint-disable-line no-unused-vars
     const tmpl = this.dom.cloneTemplate('#tmpl-lh-gauge', this.templateContext);
     const wrapper = /** @type {HTMLAnchorElement} */ (this.dom.find('.lh-gauge__wrapper', tmpl));
     wrapper.href = `#${category.id}`;
@@ -387,7 +389,7 @@ class CategoryRenderer {
   render(category, groupDefinitions = {}) {
     const element = this.dom.createElement('div', 'lh-category');
     this.createPermalinkSpan(element, category.id);
-    element.appendChild(this.renderCategoryHeader(category));
+    element.appendChild(this.renderCategoryHeader(category, groupDefinitions));
 
     // Top level clumps for audits, in order they will appear in the report.
     /** @type {Map<TopLevelClumpId, Array<LH.ReportResult.AuditRef>>} */
diff --git a/lighthouse-core/report/html/renderer/performance-category-renderer.js b/lighthouse-core/report/html/renderer/performance-category-renderer.js
index 327fa164be60..252b667016bb 100644
--- a/lighthouse-core/report/html/renderer/performance-category-renderer.js
+++ b/lighthouse-core/report/html/renderer/performance-category-renderer.js
@@ -120,11 +120,11 @@ class PerformanceCategoryRenderer extends CategoryRenderer {
     const element = this.dom.createElement('div', 'lh-category');
     if (environment === 'PSI') {
       const gaugeEl = this.dom.createElement('div', 'lh-score__gauge');
-      gaugeEl.appendChild(this.renderScoreGauge(category));
+      gaugeEl.appendChild(this.renderScoreGauge(category, groups));
       element.appendChild(gaugeEl);
     } else {
       this.createPermalinkSpan(element, category.id);
-      element.appendChild(this.renderCategoryHeader(category));
+      element.appendChild(this.renderCategoryHeader(category, groups));
     }
 
     // Metrics
diff --git a/lighthouse-core/report/html/renderer/pwa-category-renderer.js b/lighthouse-core/report/html/renderer/pwa-category-renderer.js
index 7c9be675aaba..2b547b738c9c 100644
--- a/lighthouse-core/report/html/renderer/pwa-category-renderer.js
+++ b/lighthouse-core/report/html/renderer/pwa-category-renderer.js
@@ -27,7 +27,7 @@ class PwaCategoryRenderer extends CategoryRenderer {
   render(category, groupDefinitions = {}) {
     const categoryElem = this.dom.createElement('div', 'lh-category');
     this.createPermalinkSpan(categoryElem, category.id);
-    categoryElem.appendChild(this.renderCategoryHeader(category));
+    categoryElem.appendChild(this.renderCategoryHeader(category, groupDefinitions));
 
     const auditRefs = category.auditRefs;
 
@@ -48,12 +48,13 @@ class PwaCategoryRenderer extends CategoryRenderer {
 
   /**
    * @param {LH.ReportResult.Category} category
+   * @param {Record<string, LH.Result.ReportGroup>} groupDefinitions
    * @return {DocumentFragment}
    */
-  renderScoreGauge(category) {
+  renderScoreGauge(category, groupDefinitions) {
     // Defer to parent-gauge style if category error.
     if (category.score === null) {
-      return super.renderScoreGauge(category);
+      return super.renderScoreGauge(category, groupDefinitions);
     }
 
     const tmpl = this.dom.cloneTemplate('#tmpl-lh-gauge--pwa', this.templateContext);
@@ -73,6 +74,7 @@ class PwaCategoryRenderer extends CategoryRenderer {
     }
 
     this.dom.find('.lh-gauge__label', tmpl).textContent = category.title;
+    wrapper.title = this._getGaugeTooltip(category.auditRefs, groupDefinitions);
     return tmpl;
   }
 
@@ -104,6 +106,28 @@ class PwaCategoryRenderer extends CategoryRenderer {
     return uniqueGroupIds;
   }
 
+  /**
+   * Returns a tooltip string summarizing group pass rates.
+   * @param {Array<LH.ReportResult.AuditRef>} auditRefs
+   * @param {Record<string, LH.Result.ReportGroup>} groupDefinitions
+   * @return {string}
+   */
+  _getGaugeTooltip(auditRefs, groupDefinitions) {
+    const groupIds = this._getGroupIds(auditRefs);
+
+    const tips = [];
+    for (const groupId of groupIds) {
+      const groupAuditRefs = auditRefs.filter(ref => ref.group === groupId);
+      const auditCount = groupAuditRefs.length;
+      const passedCount = groupAuditRefs.filter(ref => Util.showAsPassed(ref.result)).length;
+
+      const title = groupDefinitions[groupId].title;
+      tips.push(`${title}: ${passedCount}/${auditCount}`);
+    }
+
+    return tips.join(', ');
+  }
+
   /**
    * Render non-manual audits in groups, giving a badge to any group that has
    * all passing audits.
diff --git a/lighthouse-core/report/html/renderer/report-renderer.js b/lighthouse-core/report/html/renderer/report-renderer.js
index c95d7e2ba274..8b9559fa4814 100644
--- a/lighthouse-core/report/html/renderer/report-renderer.js
+++ b/lighthouse-core/report/html/renderer/report-renderer.js
@@ -211,7 +211,7 @@ class ReportRenderer {
       const customGauges = [];
       for (const category of report.reportCategories) {
         const renderer = specificCategoryRenderers[category.id] || categoryRenderer;
-        const categoryGauge = renderer.renderScoreGauge(category);
+        const categoryGauge = renderer.renderScoreGauge(category, report.categoryGroups || {});
 
         // Group gauges that aren't default at the end of the header
         if (renderer.renderScoreGauge === categoryRenderer.renderScoreGauge) {
diff --git a/lighthouse-core/test/report/html/renderer/pwa-category-renderer-test.js b/lighthouse-core/test/report/html/renderer/pwa-category-renderer-test.js
index 03043112d248..5698032e9e12 100644
--- a/lighthouse-core/test/report/html/renderer/pwa-category-renderer-test.js
+++ b/lighthouse-core/test/report/html/renderer/pwa-category-renderer-test.js
@@ -119,6 +119,7 @@ describe('PwaCategoryRenderer', () => {
 
       const targetGroupId = groupIds[2];
       assert.ok(targetGroupId);
+      const targetGroupTitle = sampleResults.categoryGroups[targetGroupId].title;
       const targetAuditRefs = auditRefs.filter(ref => ref.group === targetGroupId);
 
       // Try every permutation of audit scoring.
@@ -134,13 +135,25 @@ describe('PwaCategoryRenderer', () => {
         const badgedScoreGauge =
           categoryElem.querySelector('.lh-gauge--pwa__wrapper[class*="lh-badged--"]');
 
+        const tooltip = categoryElem.querySelector('.lh-gauge--pwa__wrapper').title;
+        const targetGroupTip = tooltip.split(', ').find(tip => tip.startsWith(targetGroupTitle));
+        assert.ok(targetGroupTip);
+
         // Only expect a badge (and badged gauge) on last permutation (all bits are set).
         if (i !== totalPermutations - 1) {
           assert.strictEqual(badgedElems.length, 0);
           assert.strictEqual(badgedScoreGauge, null);
+
+          // Tooltip ends with passing/total.
+          const passingCount = categoryElem.querySelectorAll(
+              `.lh-audit-group--${targetGroupId} .lh-audit--pass`).length;
+          assert.ok(targetGroupTip.endsWith(`${passingCount}/${targetAuditRefs.length}`));
         } else {
           assert.strictEqual(badgedElems.length, 1);
           assert.ok(badgedScoreGauge.classList.contains(`lh-badged--${targetGroupId}`));
+
+          // Tooltip ends with total/total.
+          assert.ok(targetGroupTip.endsWith(`${targetAuditRefs.length}/${targetAuditRefs.length}`));
         }
       }
     });
@@ -152,7 +165,17 @@ describe('PwaCategoryRenderer', () => {
 
       const categoryElem = pwaRenderer.render(category, sampleResults.categoryGroups);
       assert.strictEqual(categoryElem.querySelectorAll('.lh-badged').length, groupIds.length);
-      assert.ok(categoryElem.querySelector('.lh-gauge--pwa__wrapper.lh-badged--all'));
+
+      // Score gauge.
+      const gaugeElem = categoryElem.querySelector('.lh-gauge--pwa__wrapper');
+      assert.ok(gaugeElem.classList.contains('lh-badged--all'));
+
+      // All tooltips should have x/x audits passed.
+      const tips = gaugeElem.title.split(', ');
+      assert.strictEqual(tips.length, groupIds.length);
+      for (const tip of tips) {
+        assert.ok(/(\d+)\/\1$/.test(tip));
+      }
     });
 
     it('renders no badges when no audit groups are passing', () => {
@@ -162,8 +185,17 @@ describe('PwaCategoryRenderer', () => {
 
       const categoryElem = pwaRenderer.render(category, sampleResults.categoryGroups);
       assert.strictEqual(categoryElem.querySelectorAll('.lh-badged').length, 0);
-      assert.strictEqual(categoryElem.querySelector('.lh-gauge--pwa__wrapper[class*="lh-badged-"]'),
-        null);
+
+      // Score gauge.
+      const gaugeElem = categoryElem.querySelector('.lh-gauge--pwa__wrapper');
+      assert.ok(!gaugeElem.matches('.lh-gauge--pwa__wrapper[class*="lh-badged-"]'));
+
+      // All tooltips should have 0/x audits passed.
+      const tips = gaugeElem.title.split(', ');
+      assert.strictEqual(tips.length, groupIds.length);
+      for (const tip of tips) {
+        assert.ok(/0\/\d+$/.test(tip));
+      }
     });
 
     it('renders all but one badge when all groups but one are passing', () => {
@@ -176,13 +208,33 @@ describe('PwaCategoryRenderer', () => {
       const categoryElem = pwaRenderer.render(category, sampleResults.categoryGroups);
       const gaugeElem = categoryElem.querySelector('.lh-gauge--pwa__wrapper');
 
+      const tips = gaugeElem.title.split(', ');
+      assert.strictEqual(tips.length, groupIds.length);
+
       for (const groupId of groupIds) {
         const expectedCount = groupId === failingGroupId ? 0 : 1;
 
+        // Individual group badges.
         const groupElems = categoryElem.querySelectorAll(`.lh-audit-group--${groupId}.lh-badged`);
         assert.strictEqual(groupElems.length, expectedCount);
 
-        gaugeElem.classList.contains(`lh-badged--${groupId}`);
+        // Score gauge.
+        if (groupId !== failingGroupId) {
+          assert.ok(gaugeElem.classList.contains(`lh-badged--${groupId}`));
+        }
+
+        // Map back from groupId to groupTitle (used in tooltip).
+        const groupTitle = sampleResults.categoryGroups[groupId].title;
+        const groupTip = tips.find(tip => tip.startsWith(groupTitle));
+        assert.ok(groupTip);
+
+        // All tooltips should be x/x except for failingGroup, which should be (x-1)/x.
+        if (groupId !== failingGroupId) {
+          assert.ok(/(\d+)\/\1$/.test(groupTip));
+        } else {
+          const [, passingCount, totalCount] = /(\d+)\/(\d+)$/.exec(groupTip);
+          assert.strictEqual(Number(passingCount) + 1, Number(totalCount));
+        }
       }
     });
   });