diff --git a/src/duration.ts b/src/duration.ts
index 0195fc2..55f8d35 100644
--- a/src/duration.ts
+++ b/src/duration.ts
@@ -145,6 +145,77 @@ export function applyDuration(date: Date | number, duration: Duration): Date {
   return r
 }
 
+function applyCalendarMonths(reference: Date, months: number): Date {
+  const result = new Date(reference)
+  result.setUTCMonth(result.getUTCMonth() + months)
+  return result
+}
+
+function hasSameTimeAtPrecision(date: Date, reference: Date, precisionIndex: number): boolean {
+  if (precisionIndex <= unitNames.indexOf('day')) return true
+  if (date.getUTCHours() !== reference.getUTCHours()) return false
+  if (precisionIndex === unitNames.indexOf('hour')) return true
+  if (date.getUTCMinutes() !== reference.getUTCMinutes()) return false
+  if (precisionIndex === unitNames.indexOf('minute')) return true
+  if (date.getUTCSeconds() !== reference.getUTCSeconds()) return false
+  if (precisionIndex === unitNames.indexOf('second')) return true
+  return date.getUTCMilliseconds() === reference.getUTCMilliseconds()
+}
+
+function calendarElapsedTime(
+  date: Date,
+  reference: Date,
+  precisionIndex: number,
+  estimatedYears: number,
+): Duration | undefined {
+  const calendarMonths =
+    (date.getUTCFullYear() - reference.getUTCFullYear()) * 12 + date.getUTCMonth() - reference.getUTCMonth()
+
+  // Anchor the candidate month count to the reference, then back it off if it
+  // crossed the target. This prevents 30-day estimates from inventing a year.
+  let wholeMonths = calendarMonths
+  let anchor = applyCalendarMonths(reference, calendarMonths)
+  const candidateOvershot = calendarMonths > 0 ? anchor > date : anchor < date
+  if (candidateOvershot) {
+    wholeMonths += calendarMonths > 0 ? -1 : 1
+    anchor = applyCalendarMonths(reference, wholeMonths)
+  }
+
+  const calendarYears = Math.trunc(wholeMonths / 12)
+  const estimatedFalseYear = calendarYears !== estimatedYears
+  const sameCalendarDay = date.getUTCDate() === reference.getUTCDate()
+  const isAnniversary = Math.abs(calendarMonths) >= 12 && sameCalendarDay
+  const isCalendarAligned =
+    sameCalendarDay && (isAnniversary || hasSameTimeAtPrecision(date, reference, precisionIndex))
+  if (!estimatedFalseYear && !isCalendarAligned) return
+
+  // Exact anniversaries intentionally ignore a sub-day difference. Other
+  // corrected durations retain the remainder after the calendar-month anchor.
+  const sign = Math.sign(date.getTime() - reference.getTime())
+  const remainder = isCalendarAligned ? 0 : Math.abs(date.getTime() - anchor.getTime())
+  const seconds = Math.floor(remainder / 1000)
+  const minutes = Math.floor(seconds / 60)
+  const hours = Math.floor(minutes / 60)
+  const days = Math.floor(hours / 24)
+
+  let years = 0
+  let months = 0
+  const durationMonths = isCalendarAligned ? calendarMonths : wholeMonths
+  const durationYears = Math.trunc(durationMonths / 12)
+  if (precisionIndex >= unitNames.indexOf('year')) years = durationYears
+  if (precisionIndex >= unitNames.indexOf('month')) months = durationMonths - durationYears * 12
+  return new Duration(
+    years,
+    months,
+    0,
+    precisionIndex >= unitNames.indexOf('day') ? days * sign : 0,
+    precisionIndex >= unitNames.indexOf('hour') ? (hours - days * 24) * sign : 0,
+    precisionIndex >= unitNames.indexOf('minute') ? (minutes - hours * 60) * sign : 0,
+    precisionIndex >= unitNames.indexOf('second') ? (seconds - minutes * 60) * sign : 0,
+    precisionIndex >= unitNames.indexOf('millisecond') ? (remainder - seconds * 1000) * sign : 0,
+  )
+}
+
 export function elapsedTime(date: Date, precision: Unit = 'second', now = Date.now()): Duration {
   const delta = date.getTime() - now
   if (delta === 0) return new Duration()
@@ -157,6 +228,11 @@ export function elapsedTime(date: Date, precision: Unit = 'second', now = Date.n
   const month = Math.floor(day / 30)
   const year = Math.floor(month / 12)
   const i = unitNames.indexOf(precision)
+
+  const nowDate = new Date(now)
+  const calendarDuration = calendarElapsedTime(date, nowDate, i, year * sign)
+  if (calendarDuration) return calendarDuration
+
   return new Duration(
     i >= 0 ? year * sign : 0,
     i >= 1 ? (month - year * 12) * sign : 0,
diff --git a/test/duration.ts b/test/duration.ts
index 87707de..7edb641 100644
--- a/test/duration.ts
+++ b/test/duration.ts
@@ -107,7 +107,7 @@ suite('duration', function () {
       {
         now: '2022-01-21T16:48:44.104Z',
         input: '2022-10-21T16:48:44.104Z',
-        expected: 'P9M3D',
+        expected: 'P9M',
       },
       {
         now: '2022-01-21T16:48:44.104Z',
@@ -118,7 +118,7 @@ suite('duration', function () {
         now: '2022-01-21T16:48:44.104Z',
         input: '2022-10-21T16:48:45.104Z',
         precision: 'day',
-        expected: 'P9M3D',
+        expected: 'P9M',
       },
       {
         now: '2022-10-21T16:44:44.104Z',
@@ -218,7 +218,7 @@ suite('duration', function () {
       {
         now: '2022-10-24T14:46:00.000Z',
         input: '2021-10-29T14:46:00.000Z',
-        expected: '-P1Y',
+        expected: '-P11M26D',
       },
       {
         now: '2023-03-23T12:03:00.000Z',
@@ -237,6 +237,12 @@ suite('duration', function () {
         precision: 'year',
         expected: '-P2Y',
       },
+      {
+        now: '2023-01-01T00:00:00.000Z',
+        input: '2023-12-31T00:00:00.000Z',
+        precision: 'year',
+        expected: 'PT0S',
+      },
       {
         now: '2022-10-24T14:46:00.000Z',
         input: '2024-10-24T14:46:00.000Z',
diff --git a/test/relative-time.js b/test/relative-time.js
index 59b658b..e92d4d8 100644
--- a/test/relative-time.js
+++ b/test/relative-time.js
@@ -1559,7 +1559,7 @@ suite('relative-time', function () {
       {
         datetime: '2024-10-24T14:46:00.000Z',
         format: 'duration',
-        expected: '2 years, 11 days',
+        expected: '2 years',
       },
       {
         datetime: '2024-10-24T14:46:00.000Z',
@@ -1571,19 +1571,19 @@ suite('relative-time', function () {
         datetime: '2024-10-24T14:46:00.000Z',
         format: 'duration',
         precision: 'minute',
-        expected: '2 years, 11 days',
+        expected: '2 years',
       },
       {
         datetime: '2024-10-24T14:46:00.000Z',
         format: 'duration',
         precision: 'day',
-        expected: '2 years, 11 days',
+        expected: '2 years',
       },
       {
         datetime: '2024-10-24T14:46:00.000Z',
         format: 'duration',
         tense: 'future',
-        expected: '2 years, 11 days',
+        expected: '2 years',
       },
       {
         datetime: '2024-10-24T14:46:00.000Z',
@@ -2015,19 +2015,19 @@ suite('relative-time', function () {
       {
         datetime: '2020-10-24T14:46:00.000Z',
         format: 'duration',
-        expected: '2 years, 10 days',
+        expected: '2 years',
       },
       {
         datetime: '2020-10-24T14:46:00.000Z',
         format: 'duration',
         precision: 'minute',
-        expected: '2 years, 10 days',
+        expected: '2 years',
       },
       {
         datetime: '2020-10-24T14:46:00.000Z',
         format: 'duration',
         precision: 'day',
-        expected: '2 years, 10 days',
+        expected: '2 years',
       },
       {
         datetime: '2020-10-24T14:46:00.000Z',
@@ -2039,7 +2039,7 @@ suite('relative-time', function () {
         datetime: '2020-10-24T14:46:00.000Z',
         format: 'duration',
         tense: 'past',
-        expected: '2 years, 10 days',
+        expected: '2 years',
       },
       {
         reference: '2023-03-23T12:03:00.000Z',
@@ -2048,6 +2048,66 @@ suite('relative-time', function () {
         tense: 'past',
         expected: '2 days ago',
       },
+
+      // Whole years shouldn't have extra days
+      {
+        reference: '2023-01-01T09:00:00.000Z',
+        datetime: '2022-01-01T10:00:00.000Z',
+        format: 'duration',
+        tense: 'past',
+        expected: '1 year',
+      },
+      {
+        reference: '2023-01-01T00:00:00.000Z',
+        datetime: '2021-01-01T00:00:00.000Z',
+        format: 'duration',
+        tense: 'past',
+        expected: '2 years',
+      },
+      {
+        reference: '2023-01-01T00:00:00.000Z',
+        datetime: '2003-01-01T00:00:00.000Z',
+        format: 'duration',
+        tense: 'past',
+        expected: '20 years',
+      },
+      {
+        reference: '2023-02-01T00:00:00.000Z',
+        datetime: '2022-02-01T00:00:00.000Z',
+        format: 'duration',
+        tense: 'past',
+        expected: '1 year',
+      },
+      {
+        reference: '2023-03-01T00:00:00.000Z',
+        datetime: '2022-03-01T00:00:00.000Z',
+        format: 'duration',
+        tense: 'past',
+        expected: '1 year',
+      },
+      {
+        reference: '2023-04-01T00:00:00.000Z',
+        datetime: '2022-04-01T00:00:00.000Z',
+        format: 'duration',
+        tense: 'past',
+        expected: '1 year',
+      },
+
+      // Whole months shouldn't have extra days
+      {
+        reference: '2023-07-01T00:00:00.000Z',
+        datetime: '2023-05-01T00:00:00.000Z',
+        format: 'duration',
+        tense: 'past',
+        expected: '2 months',
+      },
+      {
+        reference: '2023-06-01T00:00:00.000Z',
+        datetime: '2023-04-01T00:00:00.000Z',
+        format: 'duration',
+        tense: 'past',
+        expected: '2 months',
+      },
     ])
 
     for (const {
@@ -2684,7 +2744,7 @@ suite('relative-time', function () {
       {
         datetime: '2021-10-29T14:46:00.000Z',
         format: 'elapsed',
-        expected: '1y',
+        expected: '11mo 26d',
       },
       {
         datetime: '2020-10-24T14:46:00.000Z',
@@ -3017,7 +3077,7 @@ suite('relative-time', function () {
         datetime: '2022-01-01T12:00:00.000Z',
         tense: 'past',
         format: 'micro',
-        expected: '1y ago',
+        expected: '11mo ago',
       },
       {
         reference: '2022-12-31T12:00:00.000Z',