diff --git a/study_lyte/calibrations.py b/study_lyte/calibrations.py
index 5aae964..94175a0 100644
--- a/study_lyte/calibrations.py
+++ b/study_lyte/calibrations.py
@@ -5,16 +5,27 @@
 import logging
 from dataclasses import dataclass
 from typing import List
+from datetime import datetime
+import pandas as pd
+
 setup_log()
 
 LOG = logging.getLogger('study_lyte.calibrations')
 
+class MissingMeasurementDateException(Exception):
+    """
+    Exception to raise when a probe has multiple calibrations but the date has 
+    not been specified.
+    """
+    pass
+
 
 @dataclass()
 class Calibration:
     """Small class to make accessing calibration data a bit more convenient"""
     serial: str
     calibration: dict[str, List[float]]
+    date: datetime = None
 
 
 class Calibrations:
@@ -26,16 +37,41 @@ def __init__(self, filename:Path):
         with open(filename, mode='r') as fp:
             self._info = json.load(fp)
 
-    def from_serial(self, serial:str) -> Calibration:
+    def from_serial(self, serial:str, date: datetime=None) -> Calibration:
         """ Build data object from the calibration result """
-        cal = self._info.get(serial)
-        if cal is None:
-            LOG.warning(f"No Calibration found for serial {serial}, using default")
+        calibrations = self._info.get(serial)
+        cal = None
+
+        if calibrations is None:
             cal = self._info['default']
             serial = 'UNKNOWN'
 
         else:
+            # Single calibration, returned as a dict
+            if isinstance(calibrations, dict):
+                cal = calibrations
+
+            # Account for multiple calibrations
+            elif isinstance(calibrations, list):
+                # Check the date is provided
+                if date is None and len(calibrations) > 1:
+                    raise MissingMeasurementDateException("Multiple calibrations found, but no date provided")
+                else:
+                    # Find the calibration that matches the date
+                    for c in calibrations:
+                        if date >= pd.to_datetime(c['date']):
+                            cal = c
+
+                    # No matches were found, date is too early
+                    if cal is None:
+                        LOG.warning(f"All available calibrations for {serial} are not available before {date}, using default")
+                        cal = self._info['default']
+                        serial = 'UNKNOWN'
+
+        if cal is not None and serial != 'UNKNOWN':
             LOG.info(f"Calibration found ({serial})!")
+        else:
+            LOG.warning(f"No calibration found for {serial}, using default")
 
         result = Calibration(serial=serial, calibration=cal)
         return result
diff --git a/study_lyte/profile.py b/study_lyte/profile.py
index 46faaed..2ecf495 100644
--- a/study_lyte/profile.py
+++ b/study_lyte/profile.py
@@ -96,7 +96,7 @@ def set_calibration(self, ext_calibrations:Calibrations):
         Args:
             ext_calibrations: External collection of calibrations
         """
-        cal = ext_calibrations.from_serial(self.serial_number)
+        cal = ext_calibrations.from_serial(self.serial_number, date=self.datetime)
         self._calibration = cal.calibration
 
     @property
diff --git a/tests/data/angled_measurement.csv b/tests/data/angled_measurement.csv
index b430fb4..849cd2d 100644
--- a/tests/data/angled_measurement.csv
+++ b/tests/data/angled_measurement.csv
@@ -6,7 +6,7 @@ MODEL NUMBER = 3
 SAMPLE RATE = 16000
 ZPFO = 50
 ACC. Range = 16
-Serial Num. = 252813070A020004
+Serial Num. = 252813070A020005
 time,Sensor1,Sensor2,Sensor3,Sensor4,depth,X-Axis,Y-Axis,Z-Axis
 0.0,3451,6,1216,3665,-0.5615234375,-0.49348,-0.7920499999999999,-0.12045
 6.250247868332343e-05,3438,8,1212,3666,-0.5806001142951156,-0.49361417545537245,-0.7920525373676652,-0.1206102717929017
diff --git a/tests/data/calibrations.json b/tests/data/calibrations.json
index ee29cfa..1b0609c 100644
--- a/tests/data/calibrations.json
+++ b/tests/data/calibrations.json
@@ -1,6 +1,17 @@
 {
-	"252813070A020004":{"Sensor1":[0, 0, -10, 409],
-						"comment": "Test"},
+	"252813070A020004":{
+		"Sensor1":[0, 0, -10, 409],
+		"comment": "Test"},
+
+	"252813070A020005":[
+		{"date": "2024-01-01",
+		"Sensor1":[0, 0, -10, 200],
+		"comment": "Date Test"},
+
+		{"date": "2025-05-01",
+		"Sensor1":[0, 0, -10, 600],
+		"comment": "Date Test2"}
+	],
 
 	"default":{"Sensor1":[0, 0, -1, 4096],
 		       "comment": "default"}
diff --git a/tests/test_calibration.py b/tests/test_calibration.py
index baa6389..fd07d5e 100644
--- a/tests/test_calibration.py
+++ b/tests/test_calibration.py
@@ -1,7 +1,8 @@
 import pytest
 from os.path import join
 from pathlib import Path
-from study_lyte.calibrations import Calibrations
+from study_lyte.calibrations import Calibrations, MissingMeasurementDateException
+import pandas as pd
 
 
 class TestCalibrations:
@@ -14,7 +15,10 @@ def calibrations(self, calibration_json):
         return Calibrations(calibration_json)
 
     @pytest.mark.parametrize("serial, expected", [
+        # Test actual calibration
         ("252813070A020004", -10),
+
+        # Test no calibration found
         ("NONSENSE", -1),
     ])
     def test_attributes(self, calibrations, serial, expected):
@@ -22,4 +26,21 @@ def test_attributes(self, calibrations, serial, expected):
         result = calibrations.from_serial(serial)
         assert result.calibration['Sensor1'][2] == expected
 
+    @pytest.mark.parametrize("serial, date, expected", [
+        # Test valid multi calibration between date 1 and date 2
+        ("252813070A020005", "2024-02-01", 200),
+        # Test valid multi calibration with exact match on date 2
+        ("252813070A020005", "2025-05-01", 600),
+        # Test single calibration with a date provided.
+        ("252813070A020004", "2025-01-01", 409),
+    ])
+    def test_date_based(self, calibrations, serial, date, expected):
+        """"""
+        dt = pd.to_datetime(date)
+        result = calibrations.from_serial(serial, date=dt)
+        assert result.calibration['Sensor1'][3] == expected
 
+    def test_missing_measurement_date_exception(self, calibrations):
+        """ Confirm this raises an exception when no date is provided """
+        with pytest.raises(MissingMeasurementDateException):
+            calibrations.from_serial("252813070A020005", date=None)
diff --git a/tests/test_profile.py b/tests/test_profile.py
index 172c361..ee91afa 100644
--- a/tests/test_profile.py
+++ b/tests/test_profile.py
@@ -233,6 +233,9 @@ def test_serial_number(self, profile,filename, depth_method, expected):
         ("open_air.csv", 'fused', -10),
         # Test serial number not found
         ("mores_20230119.csv", 'fused', -1),
+        # Tests the date based calibration serial in the profile
+        ("angled_measurement.csv", 'fused', -10),
+
     ])
     def test_set_calibration(self, data_dir, profile,filename, depth_method, expected):
         p = Path(join(data_dir,'calibrations.json'))