diff --git a/apps/client/src/features/base/components/property/__tests__/conversion-warning.spec.ts b/apps/client/src/features/base/components/property/__tests__/conversion-warning.spec.ts
new file mode 100644
index 000000000..2db7945ca
--- /dev/null
+++ b/apps/client/src/features/base/components/property/__tests__/conversion-warning.spec.ts
@@ -0,0 +1,104 @@
+import {
+  conversionWarning,
+  NON_USER_TARGET_TYPES,
+} from "../conversion-warning";
+
+describe("conversionWarning", () => {
+  it("returns the choice-name copy for select → text", () => {
+    expect(conversionWarning("select", "text")).toBe(
+      "Cells will be replaced with the option name.",
+    );
+  });
+
+  it("returns the same copy for status → text", () => {
+    expect(conversionWarning("status", "text")).toBe(
+      "Cells will be replaced with the option name.",
+    );
+  });
+
+  it("returns comma-list copy for multiSelect → text", () => {
+    expect(conversionWarning("multiSelect", "text")).toBe(
+      "Cells will be replaced with a comma-separated list of option names.",
+    );
+  });
+
+  it("returns person-name copy for person → text", () => {
+    expect(conversionWarning("person", "text")).toBe(
+      "Cells will be replaced with the person's name.",
+    );
+  });
+
+  it("returns file-name list copy for file → text", () => {
+    expect(conversionWarning("file", "text")).toBe(
+      "Cells will be replaced with a comma-separated list of file names.",
+    );
+  });
+
+  it("returns page-title copy for page → text", () => {
+    expect(conversionWarning("page", "text")).toBe(
+      "Cells will be replaced with the page title.",
+    );
+  });
+
+  it("returns first-item-kept copy for multiSelect → select", () => {
+    expect(conversionWarning("multiSelect", "select")).toBe(
+      "Only the first selected item per row will be kept; the rest will be discarded.",
+    );
+  });
+
+  it("returns single-item-list copy for select → multiSelect", () => {
+    expect(conversionWarning("select", "multiSelect")).toBe(
+      "Existing values become single-item lists. No data is lost.",
+    );
+  });
+
+  it("returns page-cleared copy when target is page from non-page", () => {
+    expect(conversionWarning("text", "page")).toBe(
+      "Cells that aren't already a page reference will be cleared.",
+    );
+    expect(conversionWarning("number", "page")).toBe(
+      "Cells that aren't already a page reference will be cleared.",
+    );
+  });
+
+  it("returns number-parse-cleared copy when target is number from non-numeric", () => {
+    expect(conversionWarning("select", "number")).toBe(
+      "Cells that can't be parsed as a number will be cleared.",
+    );
+  });
+
+  it("returns date-parse-cleared copy when target is date", () => {
+    expect(conversionWarning("text", "date")).toBe(
+      "Cells that can't be parsed as a date will be cleared.",
+    );
+  });
+
+  it("returns checkbox-coercion copy when target is checkbox", () => {
+    expect(conversionWarning("text", "checkbox")).toBe(
+      "Cells will be coerced (yes/true/1 become checked; everything else becomes unchecked or cleared).",
+    );
+  });
+
+  it("returns the default safe copy for text → url", () => {
+    expect(conversionWarning("text", "url")).toBe(
+      "Cells will be reinterpreted under the new type.",
+    );
+  });
+
+  it("returns the default safe copy for number → text", () => {
+    expect(conversionWarning("number", "text")).toBe(
+      "Cells will be reinterpreted under the new type.",
+    );
+  });
+
+  describe("NON_USER_TARGET_TYPES", () => {
+    it("contains exactly the 4 non-user types", () => {
+      expect(Array.from(NON_USER_TARGET_TYPES).sort()).toEqual([
+        "createdAt",
+        "formula",
+        "lastEditedAt",
+        "lastEditedBy",
+      ]);
+    });
+  });
+});
diff --git a/apps/client/src/features/base/components/property/conversion-warning.ts b/apps/client/src/features/base/components/property/conversion-warning.ts
new file mode 100644
index 000000000..9bc795414
--- /dev/null
+++ b/apps/client/src/features/base/components/property/conversion-warning.ts
@@ -0,0 +1,65 @@
+import type { BasePropertyType } from "@/features/base/types/base.types";
+
+export const NON_USER_TARGET_TYPES = new Set<BasePropertyType>([
+  "createdAt",
+  "lastEditedAt",
+  "lastEditedBy",
+  "formula",
+]);
+
+/*
+ * Returns the warning copy shown in the property-menu's
+ * `confirmTypeChange` panel before the user applies a type change.
+ * Strings are i18n source keys (translation files key them by their
+ * exact text). Buckets are ordered most-specific first; the default
+ * branch covers safe reinterpretations like text ↔ number, text → url,
+ * text → email.
+ */
+export function conversionWarning(
+  from: BasePropertyType,
+  to: BasePropertyType,
+): string {
+  if (to === "text") {
+    if (from === "select" || from === "status") {
+      return "Cells will be replaced with the option name.";
+    }
+    if (from === "multiSelect") {
+      return "Cells will be replaced with a comma-separated list of option names.";
+    }
+    if (from === "person") {
+      return "Cells will be replaced with the person's name.";
+    }
+    if (from === "file") {
+      return "Cells will be replaced with a comma-separated list of file names.";
+    }
+    if (from === "page") {
+      return "Cells will be replaced with the page title.";
+    }
+  }
+
+  if (to === "select" && from === "multiSelect") {
+    return "Only the first selected item per row will be kept; the rest will be discarded.";
+  }
+
+  if (to === "multiSelect" && from === "select") {
+    return "Existing values become single-item lists. No data is lost.";
+  }
+
+  if (to === "page") {
+    return "Cells that aren't already a page reference will be cleared.";
+  }
+
+  if (to === "number" && from !== "number") {
+    return "Cells that can't be parsed as a number will be cleared.";
+  }
+
+  if (to === "date" && from !== "date") {
+    return "Cells that can't be parsed as a date will be cleared.";
+  }
+
+  if (to === "checkbox" && from !== "checkbox") {
+    return "Cells will be coerced (yes/true/1 become checked; everything else becomes unchecked or cleared).";
+  }
+
+  return "Cells will be reinterpreted under the new type.";
+}