diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 43bd071..bd9ba48 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -16,11 +16,12 @@ jobs:
     with:
       toxdeps: tox-pypi-filter
       envs: |
-        - macos: py311
-        - windows: py311
-        - linux: py39
+        - macos: py312
+        - windows: py312
         - linux: py310
         - linux: py311
+        - linux: py312
+        - linux: py313
       coverage: 'codecov'
     secrets:
       CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
@@ -38,7 +39,7 @@ jobs:
       toxdeps: tox-pypi-filter
       envs: |
         - linux: build_docs
-          python-version: '3.11'
+          python-version: '3.12'
   publish:
     # Build wheels when pushing to any branch except main
     # publish.yml will only publish if tagged ^v.*
@@ -58,6 +59,6 @@ jobs:
       test_extras: 'dev'
       test_command: 'pytest -p no:warnings --doctest-rst --pyargs pydrad'
       submodules: false
-      python-version: '3.11'
+      python-version: '3.12'
     secrets:
       pypi_token: ${{ secrets.PYPI_TOKEN }}
diff --git a/pydrad/configure/configure.py b/pydrad/configure/configure.py
index 2823de7..186a765 100644
--- a/pydrad/configure/configure.py
+++ b/pydrad/configure/configure.py
@@ -202,7 +202,7 @@ def date(self):
         if hasattr(self, '_freeze_date') and self._freeze_date:
             return self._date
         else:
-            return datetime.datetime.now(datetime.UTC).strftime('%Y-%m-%d_%H.%M.%S UTC')
+            return datetime.datetime.utcnow().strftime('%Y-%m-%d_%H.%M.%S UTC')
 
     @property
     def templates(self,):
@@ -405,7 +405,7 @@ def minimum_cells(self):
         n_min = L / self.config['grid']['maximum_cell_width']
         if n_min.decompose().unit != u.dimensionless_unscaled:
             raise u.UnitConversionError(f'''Maximum cell width must be able to be converted to {L.unit}''')
-        return int(np.round(n_min.decompose()))
+        return int(np.ceil(n_min.decompose()))
 
     @property
     def maximum_cells(self):
diff --git a/pydrad/configure/data/defaults.asdf b/pydrad/configure/data/defaults.asdf
index edc5ebe..9b73bde 100644
--- a/pydrad/configure/data/defaults.asdf
+++ b/pydrad/configure/data/defaults.asdf
@@ -37,6 +37,7 @@ grid:
   enforce_conservation: true
   initial_refinement_level: 10
   linear_restriction: true
+  maximum_cells: 30000
   maximum_cell_width: !unit/quantity-1.1.0 {unit: !unit/unit-1.0.0 'Mm', value: 0.5}
   maximum_fractional_difference: 0.2
   maximum_refinement_level: 12
diff --git a/pydrad/configure/templates/initial_conditions.cfg b/pydrad/configure/templates/initial_conditions.cfg
index e9bb5eb..2b54263 100644
--- a/pydrad/configure/templates/initial_conditions.cfg
+++ b/pydrad/configure/templates/initial_conditions.cfg
@@ -1,6 +1,6 @@
 Initial_Conditions/profiles/initial.amr
 
-{{ general.loop_length | is_required | units_filter('cm') | sci_notation }}
+{{ general.loop_length | is_required | units_filter('cm') | sci_notation(sig_figs=4) }}
 {{ general.loop_inclination | is_required | units_filter('deg') }}
 {{ general.footpoint_height | is_required | units_filter('cm') | sci_notation }}
 
diff --git a/pydrad/configure/tests/test_templates.py b/pydrad/configure/tests/test_templates.py
index fe073ae..3149cc7 100644
--- a/pydrad/configure/tests/test_templates.py
+++ b/pydrad/configure/tests/test_templates.py
@@ -316,7 +316,7 @@ def test_initial_conditions_config(configuration):
     # Isothermal case
     config = f"""Initial_Conditions/profiles/initial.amr
 
-9.00000000e+09
+9.0000e+09
 0.0
 5.00000000e+08
 
@@ -341,7 +341,7 @@ def test_initial_conditions_config(configuration):
     configuration.config['initial_conditions']['heating_range_fine_tuning'] = 10000
     config = f"""Initial_Conditions/profiles/initial.amr
 
-9.00000000e+09
+9.0000e+09
 0.0
 5.00000000e+08
 
diff --git a/setup.cfg b/setup.cfg
index ad9c6d2..1aec17c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -15,16 +15,16 @@ classifiers =
   License :: OSI Approved :: MIT License
   Programming Language :: Python
   Programming Language :: Python :: 3
-  Programming Language :: Python :: 3.8
-  Programming Language :: Python :: 3.9
   Programming Language :: Python :: 3.10
   Programming Language :: Python :: 3.11
+  Programming Language :: Python :: 3.12
+  Programming Language :: Python :: 3.13
   Topic :: Scientific/Engineering :: Astronomy
 
 [options]
 zip_safe = False
 packages = find:
-python_requires = >=3.9
+python_requires = >=3.10
 setup_requires = setuptools_scm
 install_requires =
     scipy
@@ -65,6 +65,7 @@ filterwarnings =
   # See https://github.com/numpy/numpy/issues/15748#issuecomment-598584838
   ignore:numpy.ndarray size changed:RuntimeWarning
   ignore:The unit 'erg' has been deprecated in the VOUnit standard.:astropy.units.core.UnitsWarning
+  ignore:datetime.datetime.utcnow\(\) is deprecated and scheduled for removal in a future version.:DeprecationWarning
 
 [coverage:run]
 omit =
diff --git a/tox.ini b/tox.ini
index ba30824..ac458a3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py{39,310,311}
+    py{310,311,312,313}
     build_docs
     codestyle
 isolated_build = true