diff --git a/desktop/src/components/workspace/surfaces/document/spreadsheetEngine.test.ts b/desktop/src/components/workspace/surfaces/document/spreadsheetEngine.test.ts
index 876ddade..b4d1c35c 100644
--- a/desktop/src/components/workspace/surfaces/document/spreadsheetEngine.test.ts
+++ b/desktop/src/components/workspace/surfaces/document/spreadsheetEngine.test.ts
@@ -210,6 +210,60 @@ describe('the shape of a sheet', () => {
     expect(grid.columnWidths[3]).toBe(72) // not said
   })
 
+  it('widens a column the file gives no width to fit its numbers, so a value is never cut to "12,000…"', async () => {
+    const grid = await firstGrid(workbookOf([{ name: 'A', rows: [['项目', '预算(元)'], ['服务器', '1,234,567,890.00'], ['差旅', '8,000.00']] }]))
+
+    // 16 digits/separators at ~6.6px, plus the cell's padding.
+    expect(grid.columnWidths[1]).toBeGreaterThanOrEqual(120)
+    // A short CJK label still gets the default floor, not a sliver.
+    expect(grid.columnWidths[0]).toBeGreaterThanOrEqual(72)
+  })
+
+  it('leaves a short column at the default width', async () => {
+    const grid = await firstGrid(workbookOf([{ name: 'A', rows: [['a', 'b'], ['c', 'd']] }]))
+
+    expect(grid.columnWidths).toEqual([72, 72])
+  })
+
+  it('caps how far a long text can widen a column', async () => {
+    const grid = await firstGrid(workbookOf([{ name: 'A', rows: [['x'.repeat(500)]] }]))
+
+    expect(grid.columnWidths[0]).toBe(360)
+  })
+
+  it('does not widen a column for a merged heading that spills over its neighbours', async () => {
+    const grid = await firstGrid(workbookOf([{
+      name: 'A',
+      rows: [['Quarterly budget summary for the whole group', '', ''], ['a', 'b', 'c']],
+      merges: [{ s: { r: 0, c: 0 }, e: { r: 0, c: 2 } }],
+    }]))
+
+    expect(grid.columnWidths).toEqual([72, 72, 72])
+  })
+
+  it('widens a stated column for a number that would otherwise be cut, as Excel would show ####', async () => {
+    // 12 characters is what the file asked for; the preview font needs more for this figure.
+    const grid = await firstGrid(workbookOf([{
+      name: 'A',
+      rows: [['预算', 1234567890.12]],
+      columns: [{ wpx: 40 }, { wpx: 40 }],
+    }]))
+
+    expect(grid.columnWidths[1]).toBeGreaterThan(40)
+    // The text column keeps the width the file set: clipping text is what Excel does too.
+    expect(grid.columnWidths[0]).toBe(40)
+  })
+
+  it('never widens a column the file sets, nor a hidden one', async () => {
+    const grid = await firstGrid(workbookOf([{
+      name: 'A',
+      rows: [['x'.repeat(100), 'y'.repeat(100)]],
+      columns: [{ wpx: 90 }, { hidden: true }],
+    }]))
+
+    expect(grid.columnWidths).toEqual([90, 0])
+  })
+
   it('keeps column widths within what can be drawn', async () => {
     const grid = await firstGrid(workbookOf([{ name: 'A', rows: [['a', 'b']], columns: [{ wpx: 2 }, { wpx: 9000 }] }]))
 
diff --git a/desktop/src/components/workspace/surfaces/document/spreadsheetEngine.ts b/desktop/src/components/workspace/surfaces/document/spreadsheetEngine.ts
index ee4b4d09..7380c6dd 100644
--- a/desktop/src/components/workspace/surfaces/document/spreadsheetEngine.ts
+++ b/desktop/src/components/workspace/surfaces/document/spreadsheetEngine.ts
@@ -91,6 +91,9 @@ export type SpreadsheetEngineOptions = {
 const DEFAULT_COLUMN_WIDTH = 72
 const MIN_COLUMN_WIDTH = 28
 const MAX_COLUMN_WIDTH = 480
+/** A column grows to fit its text or numbers, up to this. */
+const MAX_AUTO_COLUMN_WIDTH = 360
+const CELL_PADDING = 18
 const MIN_ROW_HEIGHT = 16
 const MAX_ROW_HEIGHT = 400
 
@@ -120,6 +123,31 @@ function cellAlign(cell: SheetJs.CellObject): CellAlign {
   return 'left'
 }
 
+/** Rendered width of cell text at the grid's 12px size; a CJK character is about twice a Latin one. */
+function textWidth(text: string): number {
+  let width = 0
+  for (const char of text) width += (char.codePointAt(0) ?? 0) >= 0x2e80 ? 12 : 6.6
+  return width
+}
+
+/**
+ * How wide a column must be to show its cells whole. Excel would draw a number that does
+ * not fit as `####`; a preview that cuts it to `12,000…` hides the value just the same, and
+ * the preview's font is wider than the one the width was chosen for. `numbersOnly` is for a
+ * column whose width the file states: its text may still be clipped, as Excel clips it, but
+ * a number may not. A merged cell's text spills over its span, so it takes no part.
+ */
+function fitColumnWidth(cells: Grid['cells'], column: number, spilling: ReadonlySet<string>, numbersOnly: boolean): number {
+  let widest = 0
+  for (let row = 0; row < cells.length; row += 1) {
+    const cell = cells[row]?.[column]
+    if (!cell || spilling.has(`${row}:${column}`)) continue
+    if (numbersOnly && cell.align !== 'right') continue
+    widest = Math.max(widest, textWidth(cell.text))
+  }
+  return widest === 0 ? 0 : Math.min(Math.ceil(widest + CELL_PADDING), MAX_AUTO_COLUMN_WIDTH)
+}
+
 /** Turn a dense SheetJS worksheet into the grid the viewer draws, and let SheetJS's objects go. */
 function toGrid(sheet: SheetJs.WorkSheet, limits: SpreadsheetLimits): Grid {
   const data = ((sheet as SheetJs.DenseSheet)['!data'] ?? []) as Array<Array<SheetJs.CellObject | undefined> | undefined>
@@ -153,11 +181,19 @@ function toGrid(sheet: SheetJs.WorkSheet, limits: SpreadsheetLimits): Grid {
     cells.push(line)
   }
 
+  const spilling = new Set<string>()
+  for (const range of sheet['!merges'] ?? []) {
+    if (range.e.c > range.s.c) spilling.add(`${range.s.r}:${range.s.c}`)
+  }
+
   const columnInfo = sheet['!cols'] ?? []
   const columnWidths = Array.from({ length: columns }, (_, column) => {
     const info = columnInfo[column]
     if (info?.hidden) return 0
-    const width = info?.wpx ?? (info?.wch ? info.wch * 7 + 5 : DEFAULT_COLUMN_WIDTH)
+    const stated = info?.wpx ?? (info?.wch ? info.wch * 7 + 5 : undefined)
+    const width = stated === undefined
+      ? Math.max(DEFAULT_COLUMN_WIDTH, fitColumnWidth(cells, column, spilling, false))
+      : Math.max(stated, fitColumnWidth(cells, column, spilling, true))
     return clamp(Math.round(width), MIN_COLUMN_WIDTH, MAX_COLUMN_WIDTH)
   })