diff --git a/crates/polars-time/src/windows/duration.rs b/crates/polars-time/src/windows/duration.rs
index c8ce6832f6ac..ce5e7e7280e5 100644
--- a/crates/polars-time/src/windows/duration.rs
+++ b/crates/polars-time/src/windows/duration.rs
@@ -350,13 +350,15 @@ impl Duration {
     #[doc(hidden)]
     pub const fn duration_us(&self) -> i64 {
         self.months * 28 * 24 * 3600 * MICROSECONDS
-            + (self.weeks * NS_WEEK + self.nsecs + self.days * NS_DAY) / 1000
+            + (self.weeks * NS_WEEK / 1000 + self.nsecs / 1000 + self.days * NS_DAY / 1000)
     }
 
     #[doc(hidden)]
     pub const fn duration_ms(&self) -> i64 {
         self.months * 28 * 24 * 3600 * MILLISECONDS
-            + (self.weeks * NS_WEEK + self.nsecs + self.days * NS_DAY) / 1_000_000
+            + (self.weeks * NS_WEEK / 1_000_000
+                + self.nsecs / 1_000_000
+                + self.days * NS_DAY / 1_000_000)
     }
 
     #[doc(hidden)]
@@ -689,7 +691,7 @@ impl Duration {
         }
 
         if d.weeks > 0 {
-            let t_weeks = nsecs_to_unit(self.weeks * NS_WEEK);
+            let t_weeks = nsecs_to_unit(NS_WEEK) * self.weeks;
             match tz {
                 #[cfg(feature = "timezones")]
                 Some(tz) => {
@@ -707,7 +709,7 @@ impl Duration {
         }
 
         if d.days > 0 {
-            let t_days = nsecs_to_unit(self.days * NS_DAY);
+            let t_days = nsecs_to_unit(NS_DAY) * self.days;
             match tz {
                 #[cfg(feature = "timezones")]
                 Some(tz) => {
diff --git a/py-polars/tests/unit/functions/range/test_date_range.py b/py-polars/tests/unit/functions/range/test_date_range.py
index b5fc889ab008..a8ce8ccf0c28 100644
--- a/py-polars/tests/unit/functions/range/test_date_range.py
+++ b/py-polars/tests/unit/functions/range/test_date_range.py
@@ -369,3 +369,10 @@ def test_date_range_24h_interval_results_in_datetime() -> None:
         "date", [datetime(2022, 1, 1), datetime(2022, 1, 2), datetime(2022, 1, 3)]
     )
     assert_series_equal(result.collect().to_series(), expected)
+
+
+def test_long_date_range_12461() -> None:
+    result = pl.date_range(date(1900, 1, 1), date(2300, 1, 1), "1d", eager=True)
+    assert result[0] == date(1900, 1, 1)
+    assert result[-1] == date(2300, 1, 1)
+    assert (result.diff()[1:].dt.total_days() == 1).all()