diff --git a/HISTORY.md b/HISTORY.md
index 509c12820..0d0b59162 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -3,6 +3,8 @@
 
 # not yet published, version 6.6.3
 
+- Fix #1808: methods `.toNumber()` and `.toNumeric()` not working on a 
+  unitless unit.
 - Fix #1645: not being able to use named operators `mod`, `and`, `not`, `or`,
   `xor`, `to`, `in` as object keys. Thanks @Veeloxfire.
 - Fix `eigs` not using `config.epsilon`.
diff --git a/src/type/unit/Unit.js b/src/type/unit/Unit.js
index 76f9116e0..7bc8137c8 100644
--- a/src/type/unit/Unit.js
+++ b/src/type/unit/Unit.js
@@ -880,7 +880,7 @@ export const createUnitClass = /* #__PURE__ */ factory(name, dependencies, ({
       other = this.clone()
     }
 
-    if (other._isDerived()) {
+    if (other._isDerived() || other.units.length === 0) {
       return other._denormalize(other.value)
     } else {
       return other._denormalize(other.value, other.units[0].prefix.value)
diff --git a/test/unit-tests/type/unit/Unit.test.js b/test/unit-tests/type/unit/Unit.test.js
index 037b7ad77..3808be575 100644
--- a/test/unit-tests/type/unit/Unit.test.js
+++ b/test/unit-tests/type/unit/Unit.test.js
@@ -231,6 +231,11 @@ describe('Unit', function () {
       const u = new Unit(math.fraction(5), 'cm')
       assert.strictEqual(u.toNumber('mm'), 50)
     })
+
+    it('should convert a unit with value only to a number', function () {
+      const u = Unit.parse('5', { allowNoUnits: true })
+      assert.strictEqual(u.toNumber(), 5)
+    })
   })
 
   describe('toNumeric', function () {
@@ -349,6 +354,11 @@ describe('Unit', function () {
       assert.strictEqual(u4.fixPrefix, true)
     })
 
+    it('should convert a unitless quantity', function () {
+      const u = Unit.parse('5', { allowNoUnits: true })
+      assert.strictEqual(u.toNumeric(), 5)
+    })
+
     it('should convert a binary prefixes (1)', function () {
       const u1 = new Unit(1, 'Kib')
       assert.strictEqual(u1.value, 1024)