diff --git a/CHANGELOG.md b/CHANGELOG.md
index bce7dfeb0..31527104e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,9 @@
 ## next release
 
 ### Features
+
+* add possibility to convert hex to in in `calculator` processor with new added function `from_hex`
+
 ### Improvements
 ### Bugfix
 
diff --git a/logprep/processor/calculator/fourFn.py b/logprep/processor/calculator/fourFn.py
index 65612d716..2e28f2143 100644
--- a/logprep/processor/calculator/fourFn.py
+++ b/logprep/processor/calculator/fourFn.py
@@ -46,6 +46,7 @@
     "exp": math.exp,
     "abs": abs,
     "trunc": int,
+    "from_hex": lambda a: int(a, 16),
     "round": round,
     "sgn": lambda a: -1 if a < -epsilon else 1 if a > epsilon else 0,
     # functionsl with multiple arguments
@@ -80,7 +81,7 @@ class BNF(Forward):
     #                    Optional(e + Word("+-"+nums, nums)))
     # or use provided pyparsing_common.number, but convert back to str:
     # fnumber = ppc.number().addParseAction(lambda t: str(t[0]))
-    fnumber = Regex(r"[+-]?\d+(?:\.\d*)?(?:[eE][+-]?\d+)?")
+    fnumber = Regex(r"[+-]?[a-z0-9]+(?:\.\d*)?(?:[eE][+-]?\d+)?")
     ident = Word(alphas, alphanums + "_$")
 
     plus, minus, mult, div = map(Literal, "+-*/")
@@ -124,7 +125,10 @@ def evaluate_stack(self):
         try:
             return int(op)
         except ValueError:
-            return float(op)
+            try:
+                return float(op)
+            except ValueError:
+                return op
 
     def __new__(cls):
         if not hasattr(cls, "instance"):
diff --git a/tests/unit/processor/calculator/test_calculator.py b/tests/unit/processor/calculator/test_calculator.py
index 459abefba..94292ae99 100644
--- a/tests/unit/processor/calculator/test_calculator.py
+++ b/tests/unit/processor/calculator/test_calculator.py
@@ -176,12 +176,24 @@
         {
             "filter": "message",
             "calculator": {
-                "calc": "int(${field1}, 16)",
+                "calc": "from_hex(0x${field1})",
                 "target_field": "new_field",
             },
         },
-        {"message": "This is a message", "field1": "01e15"},
-        {"message": "This is a message", "field1": "1", "new_field": 485},
+        {"message": "This is a message", "field1": "ff"},
+        {"message": "This is a message", "field1": "ff", "new_field": 255},
+    ),
+    (
+        "convert hex to int with prefix",
+        {
+            "filter": "message",
+            "calculator": {
+                "calc": "from_hex(${field1})",
+                "target_field": "new_field",
+            },
+        },
+        {"message": "This is a message", "field1": "0xff"},
+        {"message": "This is a message", "field1": "0xff", "new_field": 255},
     ),
 ]
 
@@ -362,6 +374,7 @@ def test_testcases_failure_handling(
             ("10+sin(PI/4)^2", 10 + math.sin(math.pi / 4) ** 2),
             ("trunc(E)", int(math.e)),
             ("trunc(-E)", int(-math.e)),
+            ("from_hex(0xff)", 255),
             ("round(E)", round(math.e)),
             ("round(-E)", round(-math.e)),
             ("E^PI", math.e**math.pi),