diff --git a/src/lexer.rs b/src/lexer.rs
index 525bf42..301dfd4 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -277,6 +277,7 @@ pub fn lex(input: &str, allow_trailing_operators: bool, default_degree: Unit) ->
                 }
               }
             },
+            "stone" | "stones" => tokens.push(Token::Unit(Stone)),
             "st" | "ton" | "tons" | "short ton" | "short tons" | "short tonne" | "short tonnes" => tokens.push(Token::Unit(ShortTon)),
             "lt" | "long ton" | "long tons" | "long tonne" | "long tonnes" => tokens.push(Token::Unit(LongTon)),
 
diff --git a/src/units.rs b/src/units.rs
index 2cfec98..9c81561 100644
--- a/src/units.rs
+++ b/src/units.rs
@@ -148,6 +148,7 @@ create_units!(
   MetricTon:          (Mass, d128!(1000000)),
   Ounce:              (Mass, d128!(28.349523125)),
   Pound:              (Mass, d128!(453.59237)),
+  Stone:              (Mass, d128!(6350.29318)),
   ShortTon:           (Mass, d128!(907184.74)),
   LongTon:            (Mass, d128!(1016046.9088)),
 
@@ -769,6 +770,7 @@ mod tests {
     assert_eq!(convert_test(1000.0, Kilogram, MetricTon), 1.0);
     assert_eq!(convert_test(0.45359237, Kilogram, Pound), 1.0);
     assert_eq!(convert_test(16.0, Ounce, Pound), 1.0);
+    assert_eq!(convert_test(14.0, Pound, Stone), 1.0);
     assert_eq!(convert_test(2000.0, Pound, ShortTon), 1.0);
     assert_eq!(convert_test(2240.0, Pound, LongTon), 1.0);