diff --git a/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/CoreVitalItem.tsx b/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/CoreVitalItem.tsx
index 22d50ca0d5c41..6107a8e764adb 100644
--- a/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/CoreVitalItem.tsx
+++ b/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/CoreVitalItem.tsx
@@ -15,11 +15,11 @@ import { i18n } from '@kbn/i18n';
 import { PaletteLegends } from './PaletteLegends';
 import { ColorPaletteFlexItem } from './ColorPaletteFlexItem';
 import {
-  AVERAGE_LABEL,
-  GOOD_LABEL,
+  CV_AVERAGE_LABEL,
+  CV_GOOD_LABEL,
   LESS_LABEL,
   MORE_LABEL,
-  POOR_LABEL,
+  CV_POOR_LABEL,
 } from './translations';
 
 export interface Thresholds {
@@ -51,7 +51,7 @@ export function getCoreVitalTooltipMessage(
     values: {
       percentage,
       title: title?.toLowerCase(),
-      exp: good ? GOOD_LABEL : bad ? POOR_LABEL : AVERAGE_LABEL,
+      exp: good ? CV_GOOD_LABEL : bad ? CV_POOR_LABEL : CV_AVERAGE_LABEL,
       moreOrLess: bad || average ? MORE_LABEL : LESS_LABEL,
       value: good || average ? thresholds.good : thresholds.bad,
       averageMessage: average
@@ -90,7 +90,7 @@ export function CoreVitalItem({
       <EuiFlexGroup
         gutterSize="none"
         alignItems="flexStart"
-        style={{ maxWidth: 340 }}
+        style={{ maxWidth: 350 }}
         responsive={false}
       >
         {palette.map((hexCode, ind) => (
diff --git a/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/PaletteLegends.tsx b/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/PaletteLegends.tsx
index 84cc5f1ddb230..43eb468b88317 100644
--- a/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/PaletteLegends.tsx
+++ b/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/PaletteLegends.tsx
@@ -10,16 +10,36 @@ import {
   EuiFlexItem,
   EuiHealth,
   euiPaletteForStatus,
+  EuiText,
   EuiToolTip,
 } from '@elastic/eui';
 import styled from 'styled-components';
+import { FormattedMessage } from '@kbn/i18n/react';
+import euiLightVars from '@elastic/eui/dist/eui_theme_light.json';
+import euiDarkVars from '@elastic/eui/dist/eui_theme_dark.json';
 import { getCoreVitalTooltipMessage, Thresholds } from './CoreVitalItem';
+import { useUiSetting$ } from '../../../../../../../../src/plugins/kibana_react/public';
+import {
+  LEGEND_NEEDS_IMPROVEMENT_LABEL,
+  LEGEND_GOOD_LABEL,
+  LEGEND_POOR_LABEL,
+} from './translations';
 
 const PaletteLegend = styled(EuiHealth)`
   &:hover {
     cursor: pointer;
     text-decoration: underline;
-    background-color: #e7f0f7;
+  }
+`;
+
+const StyledSpan = styled.span<{
+  darkMode: boolean;
+}>`
+  &:hover {
+    background-color: ${(props) =>
+      props.darkMode
+        ? euiDarkVars.euiColorLightestShade
+        : euiLightVars.euiColorLightestShade};
   }
 `;
 
@@ -36,10 +56,17 @@ export function PaletteLegends({
   onItemHover,
   thresholds,
 }: Props) {
+  const [darkMode] = useUiSetting$<boolean>('theme:darkMode');
+
   const palette = euiPaletteForStatus(3);
+  const labels = [
+    LEGEND_GOOD_LABEL,
+    LEGEND_NEEDS_IMPROVEMENT_LABEL,
+    LEGEND_POOR_LABEL,
+  ];
 
   return (
-    <EuiFlexGroup responsive={false}>
+    <EuiFlexGroup responsive={false} gutterSize="s">
       {palette.map((color, ind) => (
         <EuiFlexItem
           key={ind}
@@ -60,7 +87,21 @@ export function PaletteLegends({
             )}
             position="bottom"
           >
-            <PaletteLegend color={color}>{ranks?.[ind]}%</PaletteLegend>
+            <StyledSpan darkMode={darkMode}>
+              <PaletteLegend color={color}>
+                <EuiText size="xs">
+                  {labels[ind]} ({ranks?.[ind]}%)
+                  <FormattedMessage
+                    id="xpack.apm.rum.coreVitals.paletteLegend.rankPercentage"
+                    defaultMessage="{labelsInd} ({ranksInd}%)"
+                    values={{
+                      labelsInd: labels[ind],
+                      ranksInd: ranks?.[ind],
+                    }}
+                  />
+                </EuiText>
+              </PaletteLegend>
+            </StyledSpan>
           </EuiToolTip>
         </EuiFlexItem>
       ))}
diff --git a/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/index.tsx b/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/index.tsx
index 0135f0b369537..cd7fd0af6d683 100644
--- a/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/index.tsx
+++ b/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/index.tsx
@@ -8,6 +8,7 @@ import { EuiFlexGroup, EuiFlexItem } from '@elastic/eui';
 import { CLS_LABEL, FID_LABEL, LCP_LABEL } from './translations';
 import { CoreVitalItem } from './CoreVitalItem';
 import { UXMetrics } from '../UXMetrics';
+import { formatToSec } from '../UXMetrics/KeyUXMetrics';
 
 const CoreVitalsThresholds = {
   LCP: { good: '2.5s', bad: '4.0s' },
@@ -28,7 +29,7 @@ export function CoreVitals({ data, loading }: Props) {
       <EuiFlexItem>
         <CoreVitalItem
           title={LCP_LABEL}
-          value={lcp ? lcp + ' s' : '0'}
+          value={formatToSec(lcp, 'ms')}
           ranks={lcpRanks}
           loading={loading}
           thresholds={CoreVitalsThresholds.LCP}
@@ -37,7 +38,7 @@ export function CoreVitals({ data, loading }: Props) {
       <EuiFlexItem>
         <CoreVitalItem
           title={FID_LABEL}
-          value={fid ? fid + ' s' : '0'}
+          value={formatToSec(fid, 'ms')}
           ranks={fidRanks}
           loading={loading}
           thresholds={CoreVitalsThresholds.FID}
diff --git a/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/translations.ts b/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/translations.ts
index 063d062db7650..cae1a43733713 100644
--- a/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/translations.ts
+++ b/x-pack/plugins/apm/public/components/app/RumDashboard/CoreVitals/translations.ts
@@ -47,21 +47,42 @@ export const SUM_LONG_TASKS = i18n.translate(
   }
 );
 
-export const POOR_LABEL = i18n.translate('xpack.apm.rum.coreVitals.poor', {
+export const CV_POOR_LABEL = i18n.translate('xpack.apm.rum.coreVitals.poor', {
   defaultMessage: 'a poor',
 });
 
-export const GOOD_LABEL = i18n.translate('xpack.apm.rum.coreVitals.good', {
+export const CV_GOOD_LABEL = i18n.translate('xpack.apm.rum.coreVitals.good', {
   defaultMessage: 'a good',
 });
 
-export const AVERAGE_LABEL = i18n.translate(
+export const CV_AVERAGE_LABEL = i18n.translate(
   'xpack.apm.rum.coreVitals.average',
   {
     defaultMessage: 'an average',
   }
 );
 
+export const LEGEND_POOR_LABEL = i18n.translate(
+  'xpack.apm.rum.coreVitals.legends.poor',
+  {
+    defaultMessage: 'Poor',
+  }
+);
+
+export const LEGEND_GOOD_LABEL = i18n.translate(
+  'xpack.apm.rum.coreVitals.legends.good',
+  {
+    defaultMessage: 'Good',
+  }
+);
+
+export const LEGEND_NEEDS_IMPROVEMENT_LABEL = i18n.translate(
+  'xpack.apm.rum.coreVitals.legends.needsImprovement',
+  {
+    defaultMessage: 'Needs improvement',
+  }
+);
+
 export const MORE_LABEL = i18n.translate('xpack.apm.rum.coreVitals.more', {
   defaultMessage: 'more',
 });
diff --git a/x-pack/plugins/apm/public/components/app/RumDashboard/UXMetrics/index.tsx b/x-pack/plugins/apm/public/components/app/RumDashboard/UXMetrics/index.tsx
index 3c7b4e39401de..1a95ac50587af 100644
--- a/x-pack/plugins/apm/public/components/app/RumDashboard/UXMetrics/index.tsx
+++ b/x-pack/plugins/apm/public/components/app/RumDashboard/UXMetrics/index.tsx
@@ -4,15 +4,20 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-import React from 'react';
+import React, { useState } from 'react';
 import {
+  EuiButtonIcon,
   EuiFlexGroup,
   EuiFlexItem,
   EuiHorizontalRule,
+  EuiLink,
   EuiPanel,
+  EuiPopover,
   EuiSpacer,
   EuiTitle,
+  EuiText,
 } from '@elastic/eui';
+import { FormattedMessage } from '@kbn/i18n/react';
 import { I18LABELS } from '../translations';
 import { CoreVitals } from '../CoreVitals';
 import { KeyUXMetrics } from './KeyUXMetrics';
@@ -21,8 +26,8 @@ import { useFetcher } from '../../../../hooks/useFetcher';
 
 export interface UXMetrics {
   cls: string;
-  fid: string;
-  lcp: string;
+  fid: number;
+  lcp: number;
   tbt: number;
   fcp: number;
   lcpRanks: number[];
@@ -56,6 +61,10 @@ export function UXMetrics() {
     [start, end, uiFilters, searchTerm]
   );
 
+  const [isPopoverOpen, setIsPopoverOpen] = useState(false);
+
+  const closePopover = () => setIsPopoverOpen(false);
+
   return (
     <EuiPanel>
       <EuiFlexGroup justifyContent="spaceBetween">
@@ -72,7 +81,37 @@ export function UXMetrics() {
       <EuiFlexGroup justifyContent="spaceBetween">
         <EuiFlexItem grow={1} data-cy={`client-metrics`}>
           <EuiTitle size="xs">
-            <h3>{I18LABELS.coreWebVitals}</h3>
+            <h3>
+              {I18LABELS.coreWebVitals}
+              <EuiPopover
+                isOpen={isPopoverOpen}
+                button={
+                  <EuiButtonIcon
+                    onClick={() => setIsPopoverOpen(true)}
+                    color={'text'}
+                    iconType={'questionInCircle'}
+                  />
+                }
+                closePopover={closePopover}
+              >
+                <div style={{ width: '300px' }}>
+                  <EuiText>
+                    <FormattedMessage
+                      id="xpack.apm.ux.dashboard.webCoreVitals.help"
+                      defaultMessage="Learn more about"
+                    />
+                    <EuiLink
+                      href="https://web.dev/vitals/"
+                      external
+                      target="_blank"
+                    >
+                      {' '}
+                      {I18LABELS.coreWebVitals}
+                    </EuiLink>
+                  </EuiText>
+                </div>
+              </EuiPopover>
+            </h3>
           </EuiTitle>
           <EuiSpacer size="s" />
           <CoreVitals data={data} loading={status !== 'success'} />
diff --git a/x-pack/plugins/apm/server/lib/rum_client/get_long_task_metrics.ts b/x-pack/plugins/apm/server/lib/rum_client/get_long_task_metrics.ts
index 812cf9865bda8..bd4bdb9ca3536 100644
--- a/x-pack/plugins/apm/server/lib/rum_client/get_long_task_metrics.ts
+++ b/x-pack/plugins/apm/server/lib/rum_client/get_long_task_metrics.ts
@@ -81,6 +81,7 @@ export async function getLongTaskMetrics({
       }
     }
   });
+
   return {
     noOfLongTasks,
     sumOfLongTasks,
diff --git a/x-pack/plugins/apm/server/lib/rum_client/get_web_core_vitals.ts b/x-pack/plugins/apm/server/lib/rum_client/get_web_core_vitals.ts
index fa34c2e25fecd..0828d7ab65190 100644
--- a/x-pack/plugins/apm/server/lib/rum_client/get_web_core_vitals.ts
+++ b/x-pack/plugins/apm/server/lib/rum_client/get_web_core_vitals.ts
@@ -124,13 +124,12 @@ export async function getWebCoreVitals({
     { value: 0, key: 0 },
   ];
 
-  // Divide by 1000 to convert ms into seconds
   return {
     cls: String(cls?.values['50.0']?.toFixed(2) || 0),
-    fid: ((fid?.values['50.0'] || 0) / 1000).toFixed(2),
-    lcp: ((lcp?.values['50.0'] || 0) / 1000).toFixed(2),
-    tbt: tbt?.values['50.0'] || 0,
-    fcp: fcp?.values['50.0'] || 0,
+    fid: fid?.values['50.0'] ?? 0,
+    lcp: lcp?.values['50.0'] ?? 0,
+    tbt: tbt?.values['50.0'] ?? 0,
+    fcp: fcp?.values['50.0'] ?? 0,
 
     lcpRanks: getRanksPercentages(lcpRanks?.values ?? defaultRanks),
     fidRanks: getRanksPercentages(fidRanks?.values ?? defaultRanks),
diff --git a/x-pack/test/apm_api_integration/trial/tests/csm/web_core_vitals.ts b/x-pack/test/apm_api_integration/trial/tests/csm/web_core_vitals.ts
index 6364a79a12f04..5825c8fc49a6b 100644
--- a/x-pack/test/apm_api_integration/trial/tests/csm/web_core_vitals.ts
+++ b/x-pack/test/apm_api_integration/trial/tests/csm/web_core_vitals.ts
@@ -59,13 +59,13 @@ export default function rumServicesApiTests({ getService }: FtrProviderContext)
               0,
             ],
             "fcp": 1072,
-            "fid": "1.35",
+            "fid": 1352.13,
             "fidRanks": Array [
               0,
               0,
               100,
             ],
-            "lcp": "1.27",
+            "lcp": 1270.5,
             "lcpRanks": Array [
               100,
               0,