diff --git a/magnivore/Lexicon.py b/magnivore/Lexicon.py
index 84ae7a2..acf038b 100644
--- a/magnivore/Lexicon.py
+++ b/magnivore/Lexicon.py
@@ -2,6 +2,7 @@
 import re
 from decimal import Decimal
 from functools import reduce
+from math import ceil, floor
 
 from .Tracker import Tracker
 
@@ -40,7 +41,12 @@ class Lexicon:
         """
         value = cls._dot_reduce(rule['from'], target)
         original_type = type(value)
-        return original_type(Decimal(value) * Decimal(rule['factor']))
+        result = Decimal(value) * Decimal(rule['factor'])
+        if 'round' in rule:
+            if rule['round'] == 'up':
+                return original_type(ceil(result))
+            return original_type(floor(result))
+        return original_type(result)
 
     @classmethod
     def format(cls, rule, target):

Add possibility to specify whether to round up or down in factor
diff --git a/tests/unit/Lexicon.py b/tests/unit/Lexicon.py
index f1c85d6..3af833c 100644
--- a/tests/unit/Lexicon.py
+++ b/tests/unit/Lexicon.py
@@ -65,6 +65,19 @@ def test_lexicon_factor(from_data, target, expected):
     assert type(result) == type(expected)
 
 
+@mark.parametrize('rounding, expected', [
+    ('down', 47),
+    ('up', 48)
+])
+def test_lexicon_factor_round(rounding, expected):
+    rule = {
+        'from': 'value',
+        'round': rounding,
+        'factor': 0.5
+    }
+    assert Lexicon.factor(rule, MagicMock(value=95)) == expected
+
+
 @mark.parametrize('from_data, format, expected', [
     ('birthyear', '{}-0-0', '1992-0-0'),
     (['birthyear', 'birthmonth'], '{}-{}-0', '1992-9-0')

pip install -e .[dev]
parse_log_pytest
pytest
pytest pytest-mock psycopg2 PyMySQL
apt-get update apt-get install -y gcc
3.6
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
aratrum==0.3.2
attrs @ file:///opt/conda/conda-bld/attrs_1642510447205/work
certifi==2021.5.30
click==8.0.4
importlib-metadata @ file:///tmp/build/80754af9/importlib-metadata_1631916693255/work
iniconfig @ file:///home/linux1/recipes/ci/iniconfig_1610983019677/work
-e git+https://github.com/wearewhys/magnivore.git@acf182faeb0cf80157ec5d7b448b355687dcbd94#egg=magnivore
more-itertools @ file:///tmp/build/80754af9/more-itertools_1637733554872/work
packaging @ file:///tmp/build/80754af9/packaging_1637314298585/work
peewee==3.17.9
pluggy @ file:///tmp/build/80754af9/pluggy_1615976315926/work
psycopg2==2.7.7
py @ file:///opt/conda/conda-bld/py_1644396412707/work
PyMySQL==1.0.2
pyparsing @ file:///tmp/build/80754af9/pyparsing_1635766073266/work
pytest==6.2.4
pytest-mock==3.6.1
toml @ file:///tmp/build/80754af9/toml_1616166611790/work
typing_extensions @ file:///opt/conda/conda-bld/typing_extensions_1647553014482/work
ujson==4.3.0
zipp @ file:///tmp/build/80754af9/zipp_1633618647012/work

name: magnivore
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - attrs=21.4.0=pyhd3eb1b0_0
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - importlib-metadata=4.8.1=py36h06a4308_0
  - importlib_metadata=4.8.1=hd3eb1b0_0
  - iniconfig=1.1.1=pyhd3eb1b0_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - more-itertools=8.12.0=pyhd3eb1b0_0
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - packaging=21.3=pyhd3eb1b0_0
  - pip=21.2.2=py36h06a4308_0
  - pluggy=0.13.1=py36h06a4308_0
  - py=1.11.0=pyhd3eb1b0_0
  - pyparsing=3.0.4=pyhd3eb1b0_0
  - pytest=6.2.4=py36h06a4308_2
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - toml=0.10.2=pyhd3eb1b0_0
  - typing_extensions=4.1.1=pyh06a4308_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zipp=3.6.0=pyhd3eb1b0_0
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - aratrum==0.3.2
      - click==8.0.4
      - peewee==3.17.9
      - psycopg2==2.7.7
      - pymysql==1.0.2
      - pytest-mock==3.6.1
      - ujson==4.3.0
prefix: /opt/conda/envs/magnivore

tests/unit/Lexicon.py::test_lexicon_factor_round[up-48]
tests/unit/Lexicon.py::test_lexicon_basic tests/unit/Lexicon.py::test_lexicon_basic_dot tests/unit/Lexicon.py::test_lexicon_basic_dot_double tests/unit/Lexicon.py::test_lexicon_basic_null[field] tests/unit/Lexicon.py::test_lexicon_basic_null[table.field] tests/unit/Lexicon.py::test_lexicon_basic_null[table.field.nested] tests/unit/Lexicon.py::test_lexicon_transform[target0] tests/unit/Lexicon.py::test_lexicon_transform[target1] tests/unit/Lexicon.py::test_lexicon_factor[value-target0-50] tests/unit/Lexicon.py::test_lexicon_factor[value-target1-expected1] tests/unit/Lexicon.py::test_lexicon_factor[value-target2-50.0] tests/unit/Lexicon.py::test_lexicon_factor[related.value-target3-50] tests/unit/Lexicon.py::test_lexicon_factor_round[down-47] tests/unit/Lexicon.py::test_lexicon_format[birthyear-{}-0-0-1992-0-0] tests/unit/Lexicon.py::test_lexicon_format[from_data1-{}-{}-0-1992-9-0] tests/unit/Lexicon.py::test_lexicon_format_dot[rel.birthyear-{}-0-0-1992-0-0] tests/unit/Lexicon.py::test_lexicon_format_dot[from_data1-{}-{}-0-1992-9-0] tests/unit/Lexicon.py::test_lexicon_match tests/unit/Lexicon.py::test_lexicon_match_none tests/unit/Lexicon.py::test_lexicon_match_from tests/unit/Lexicon.py::test_lexicon_match_dot tests/unit/Lexicon.py::test_lexicon_match_from_none tests/unit/Lexicon.py::test_lexicon_match_none_log tests/unit/Lexicon.py::test_lexicon_sync tests/unit/Lexicon.py::test_lexicon_sync_none tests/unit/Lexicon.py::test_lexicon_static tests/unit/Lexicon.py::test_lexicon_expression tests/unit/Lexicon.py::test_lexicon_expression_dot tests/unit/Lexicon.py::test_lexicon_expression_none
magnivore/Lexicon.py
magnivore/Lexicon.py