diff --git a/apps/api/src/jobs/__tests__/import-processor.test.ts b/apps/api/src/jobs/__tests__/import-processor.test.ts
index 05381ea..e52b140 100644
--- a/apps/api/src/jobs/__tests__/import-processor.test.ts
+++ b/apps/api/src/jobs/__tests__/import-processor.test.ts
@@ -292,8 +292,40 @@ describe('coerceCustomValue', () => {
     });
   });
 
+  describe('number coercion', () => {
+    it.each([
+      ['42', 42],
+      ['-7', -7],
+      ['3.14', 3.14],
+      [' 42 ', 42],
+      ['0.5', 0.5],
+      ['-0.25', -0.25],
+    ])('coerces %j to %j', (value, expected) => {
+      expect(coerceCustomValue(value)).toBe(expected);
+    });
+
+    it.each(['01234', '+42', '.5', '42.', '1e10', 'NaN', 'Infinity', '1.2.3', '4-2'])(
+      'leaves %j as a string (preserves IDs / rejects loose formats)',
+      value => {
+        expect(coerceCustomValue(value)).toBe(value);
+      },
+    );
+
+    it('keeps boolean precedence: "1" stays boolean true, not number 1', () => {
+      expect(coerceCustomValue('1')).toBe(true);
+    });
+
+    it('keeps boolean precedence: "0" stays boolean false, not number 0', () => {
+      expect(coerceCustomValue('0')).toBe(false);
+    });
+
+    it('"1.0" is a number (does not match the boolean truthy set)', () => {
+      expect(coerceCustomValue('1.0')).toBe(1);
+    });
+  });
+
   describe('passthrough', () => {
-    it.each(['Alice', 'true!', 'yesno', 'maybe', '42', '3.14', '01234'])('leaves %j as a string', value => {
+    it.each(['Alice', 'true!', 'yesno', 'maybe'])('leaves %j as a string', value => {
       expect(coerceCustomValue(value)).toBe(value);
     });
 
diff --git a/apps/api/src/jobs/import-processor.ts b/apps/api/src/jobs/import-processor.ts
index ef38fd4..d66f540 100644
--- a/apps/api/src/jobs/import-processor.ts
+++ b/apps/api/src/jobs/import-processor.ts
@@ -223,16 +223,22 @@ function isValidEmail(email: string): boolean {
 
 const BOOLEAN_TRUE = new Set(['true', '1', 'yes']);
 const BOOLEAN_FALSE = new Set(['false', '0', 'no']);
+// Strict integer-or-decimal pattern. Rejects leading zeros (preserves IDs,
+// zips, phone numbers), scientific notation, `+` prefix, and `.5` / `42.`.
+const NUMERIC_RE = /^-?(0|[1-9]\d*)(\.\d+)?$/;
 
 /**
  * Coerce a raw CSV cell to its natural JSON primitive so post-import type
- * inference (ContactService.getAvailableFields) can detect booleans on custom
- * fields the same way it already does for the reserved `subscribed` column.
- * Values outside the recognised keyword set are returned unchanged.
+ * inference (ContactService.getAvailableFields) can detect booleans and
+ * numbers on custom fields the same way it already does for the reserved
+ * `subscribed` column. Values that match neither recogniser are returned
+ * unchanged.
  */
-export function coerceCustomValue(value: string): string | boolean {
-  const lower = value.trim().toLowerCase();
+export function coerceCustomValue(value: string): string | boolean | number {
+  const trimmed = value.trim();
+  const lower = trimmed.toLowerCase();
   if (BOOLEAN_TRUE.has(lower)) return true;
   if (BOOLEAN_FALSE.has(lower)) return false;
+  if (NUMERIC_RE.test(trimmed)) return Number(trimmed);
   return value;
 }