diff --git a/src/cal_tools/calcat_interface.py b/src/cal_tools/calcat_interface.py
index aabee45033593c22797bc97362ed06f6517108a6..359280e5b63baf7f809722d2721d7ace4c5eb36d 100644
--- a/src/cal_tools/calcat_interface.py
+++ b/src/cal_tools/calcat_interface.py
@@ -120,10 +120,19 @@ class CalCatApi(metaclass=ClientWrapper):
             (dict) Operating condition for use in CalCat API.
         """
 
+        def to_float_or_string(value):
+            """CALCAT expects data to either be float or a string.
+            """
+            try:  # Any digit or boolean
+                return float(value)
+            except:
+                return str(value)
+
         return {
-            "parameters_conditions_attributes": [
-                {"parameter_name": k, "value": str(v)}
-                for k, v in condition.items()
+            "parameters_conditions_attributes": [{
+                "parameter_name": k,
+                "value": to_float_or_string(v)
+            } for k, v in condition.items()
             ]
         }
 
diff --git a/src/cal_tools/calcat_interface2.py b/src/cal_tools/calcat_interface2.py
index bc598d5726741c11a0a9a01983b640687702e7dc..aab6574759490a04ef576732896d0872a2cf50bb 100644
--- a/src/cal_tools/calcat_interface2.py
+++ b/src/cal_tools/calcat_interface2.py
@@ -470,9 +470,19 @@ class CalibrationData(Mapping):
             (dict) Operating condition for use in CalCat API.
         """
 
+        def to_float_or_string(value):
+            """CALCAT expects data to either be float or a string.
+            """
+            try:  # Any digit or boolean
+                return float(value)
+            except:
+                return str(value)
+
         return {
-            "parameters_conditions_attributes": [
-                {"parameter_name": k, "value": str(v)} for k, v in condition.items()
+            "parameters_conditions_attributes": [{
+                "parameter_name": k,
+                "value": to_float_or_string(v)
+            } for k, v in condition.items()
             ]
         }