diff --git a/rocketpy/units.py b/rocketpy/units.py
index b8e4c199c..f044c2782 100644
--- a/rocketpy/units.py
+++ b/rocketpy/units.py
@@ -25,14 +25,14 @@
     # Units of acceleration. Meter per square second "m/s^2" is the base unit.
     "m/s^2": 1,
     "gs": 1 / 9.80665,
-    "ft/s^2": 1 / 3.2808399,
+    "ft/s^2": 1 / 0.3048,
     # Units of pressure. Pascal "Pa" is the base unit.
     "Pa": 1,
     "hPa": 1e-2,
     "kPa": 1e-3,
     "MPa": 1e-6,
     "bar": 1e-5,
-    "atm": 1.01325e-5,
+    "atm": 1 / 101325,
     "mmHg": 1 / 133.322,
     "inHg": 1 / 3386.389,
     # Units of time. Seconds "s" is the base unit.
@@ -41,14 +41,14 @@
     "h": 1 / 3600,
     "d": 1 / 86400,
     # Units of mass. Kilogram "kg" is the base unit.
-    "mg": 1e-6,
-    "g": 1e-3,
+    "mg": 1e6,
+    "g": 1e3,
     "kg": 1,
     "lb": 2.20462,
     # Units of angle. Radian "rad" is the base unit.
     "rad": 1,
-    "deg": 1 / 180 * np.pi,
-    "grad": 1 / 200 * np.pi,
+    "deg": 180 / np.pi,
+    "grad": 200 / np.pi,
 }
 
 
diff --git a/tests/integration/simulation/test_flight_data_importer.py b/tests/integration/simulation/test_flight_data_importer.py
index 9cff30d57..653222ed1 100644
--- a/tests/integration/simulation/test_flight_data_importer.py
+++ b/tests/integration/simulation/test_flight_data_importer.py
@@ -55,3 +55,22 @@ def test_flight_importer_ndrt():
         "Can't find 'altitude' column in fd._columns"
     )
     assert np.isclose(fd.altitude(0), 0)
+
+
+def test_flight_importer_converts_imperial_and_degree_columns(tmp_path):
+    """Columns logged in ft/s^2 and degrees should be converted to SI."""
+    path = tmp_path / "log.csv"
+    path.write_text("time,accel_ft_s2,pitch_deg\n0,32.174,90\n1,32.174,90\n")
+
+    fd = FlightDataImporter(
+        paths=str(path),
+        columns_map={
+            "time": "time",
+            "accel_ft_s2": "az",
+            "pitch_deg": "attitude_angle",
+        },
+        units={"accel_ft_s2": "ft/s^2", "pitch_deg": "deg"},
+    )
+
+    assert np.isclose(fd.az(0), 32.174 * 0.3048)
+    assert np.isclose(fd.attitude_angle(0), np.pi / 2)
diff --git a/tests/unit/test_units.py b/tests/unit/test_units.py
index 8c3db1d00..f63c808c3 100644
--- a/tests/unit/test_units.py
+++ b/tests/unit/test_units.py
@@ -68,6 +68,56 @@ def test_conversion_factor_invalid_conversion(self):
 class TestConvertUnits:
     """Tests for the convert_units function."""
 
+    @pytest.mark.parametrize(
+        "unit, base_unit, value_in_base",
+        [
+            ("mm", "m", 1e-3),
+            ("cm", "m", 1e-2),
+            ("dm", "m", 1e-1),
+            ("dam", "m", 1e1),
+            ("hm", "m", 1e2),
+            ("km", "m", 1e3),
+            ("ft", "m", 0.3048),
+            ("in", "m", 0.0254),
+            ("mi", "m", 1609.344),
+            ("nmi", "m", 1852),
+            ("yd", "m", 0.9144),
+            ("km/h", "m/s", 1 / 3.6),
+            ("knot", "m/s", 1852 / 3600),
+            ("mph", "m/s", 1609.344 / 3600),
+            ("ft/s", "m/s", 0.3048),
+            ("gs", "m/s^2", 9.80665),
+            ("ft/s^2", "m/s^2", 0.3048),
+            ("hPa", "Pa", 1e2),
+            ("kPa", "Pa", 1e3),
+            ("MPa", "Pa", 1e6),
+            ("bar", "Pa", 1e5),
+            ("atm", "Pa", 101325),
+            ("mmHg", "Pa", 133.322387415),
+            ("inHg", "Pa", 3386.389),
+            ("min", "s", 60),
+            ("h", "s", 3600),
+            ("d", "s", 86400),
+            ("mg", "kg", 1e-6),
+            ("g", "kg", 1e-3),
+            ("lb", "kg", 0.45359237),
+            ("deg", "rad", np.pi / 180),
+            ("grad", "rad", np.pi / 200),
+        ],
+    )
+    def test_convert_units_matches_unit_definitions(
+        self, unit, base_unit, value_in_base
+    ):
+        """One of each unit should convert to its defined value in the base
+        unit, and back. The references are the exact SI definitions, so the
+        tolerance only allows for the rounded pound and mercury constants."""
+        assert convert_units(1, unit, base_unit) == pytest.approx(
+            value_in_base, rel=1e-5
+        )
+        assert convert_units(value_in_base, base_unit, unit) == pytest.approx(
+            1, rel=1e-5
+        )
+
     def test_convert_units_same_unit(self):
         assert convert_units(300, "K", "K") == 300
         assert convert_units(27, "degC", "degC") == 27