diff --git a/crates/xlsx/src/chart.rs b/crates/xlsx/src/chart.rs
index 182345799..836e896b6 100644
--- a/crates/xlsx/src/chart.rs
+++ b/crates/xlsx/src/chart.rs
@@ -297,9 +297,14 @@ fn ref_target(wb: &Workbook, sheet_idx: usize, f: &str) -> Option<(usize, RangeR
 pub(crate) fn ref_values(wb: &Workbook, sheet_idx: usize, f: &str) -> Option<Vec<Value>> {
     let (si, mut range) = ref_target(wb, sheet_idx, f)?;
     let sheet = wb.sheet(si)?;
-    // Whole columns/rows: limit to the used range.
+    // Whole columns/rows: cut the far end at the used range. The start stays put, so point indices keep matching the reference.
     if let Some(u) = sheet.used_range() {
-        range = range.intersection(&u)?;
+        if range.is_full_cols() {
+            range.end.row = range.end.row.min(u.end.row.max(range.start.row));
+        }
+        if range.is_full_rows() {
+            range.end.col = range.end.col.min(u.end.col.max(range.start.col));
+        }
     }
     if range.count() > MAX_CACHE {
         return None;
diff --git a/crates/xlsx/src/tests/chart_ref_offsets.rs b/crates/xlsx/src/tests/chart_ref_offsets.rs
new file mode 100644
index 000000000..87e6ba9fa
--- /dev/null
+++ b/crates/xlsx/src/tests/chart_ref_offsets.rs
@@ -0,0 +1,25 @@
+//! Chart caches keep the position of every point inside the referenced range.
+
+use gridcraft_core::{CellRef, Value};
+use gridcraft_model::{Sheet, Workbook};
+use std::sync::Arc;
+
+use crate::chart::ref_values;
+
+fn book() -> Workbook {
+    let mut s = Sheet::new("Data");
+    s.set_value(CellRef::new(3, 0), Value::Number(5.0));
+    Workbook { sheets: vec![Arc::new(s)], ..Workbook::default() }
+}
+
+#[test]
+fn explicit_range_keeps_leading_and_trailing_blanks() {
+    let vals = ref_values(&book(), 0, "Data!$A$3:$A$6").unwrap();
+    assert_eq!(vals, vec![Value::Empty, Value::Number(5.0), Value::Empty, Value::Empty]);
+}
+
+#[test]
+fn whole_column_still_stops_at_used_range_and_starts_at_top() {
+    let vals = ref_values(&book(), 0, "Data!$A:$A").unwrap();
+    assert_eq!(vals, vec![Value::Empty, Value::Empty, Value::Empty, Value::Number(5.0)]);
+}
diff --git a/crates/xlsx/src/tests/mod.rs b/crates/xlsx/src/tests/mod.rs
index eb317854e..a164aa3fa 100644
--- a/crates/xlsx/src/tests/mod.rs
+++ b/crates/xlsx/src/tests/mod.rs
@@ -2,6 +2,7 @@
 
 mod array_export;
 mod chart_bool_default;
+mod chart_ref_offsets;
 mod csv_tests;
 mod encrypted_tests;
 mod fixtures;