diff --git a/src/caf/distribute/gravity_model/multi_area.py b/src/caf/distribute/gravity_model/multi_area.py
index c2836c3..3ae2ac8 100644
--- a/src/caf/distribute/gravity_model/multi_area.py
+++ b/src/caf/distribute/gravity_model/multi_area.py
@@ -93,6 +93,17 @@ class MultiDistInput(BaseConfig):
     furness_tolerance: float = 1e-6
     furness_jac: float = False
 
+@dataclass
+class GMCalibParams:
+    furness_jac: bool = False,
+    diff_step: float = 1e-8,
+    ftol: float = 1e-4,
+    xtol: float = 1e-4,
+    furness_tol=DEFAULT_FURNESS_TOL,
+    grav_max_iters: int = 100,
+    failure_tol: float = 0,
+    default_retry: bool = True,
+
 
 @dataclass
 class MultiCostDistribution:
@@ -483,25 +494,54 @@ def _create_seed_matrix(self, cost_distributions, cost_args, params_len):
         return base_mat
 
     # pylint: disable=too-many-locals
-    def _calibrate(
+    def calibrate(
         self,
         distributions: MultiCostDistribution,
         running_log_path: Path,
-        furness_jac: bool = False,
-        diff_step: float = 1e-8,
-        ftol: float = 1e-4,
-        xtol: float = 1e-4,
-        furness_tol=DEFAULT_FURNESS_TOL,
-        grav_max_iters: int = 100,
-        failure_tol: float = 0,
-        default_retry: bool = True,
+        gm_params: GMCalibParams, 
         verbose: int = 0,
         **kwargs,
     ) -> dict[str | int, GravityModelCalibrateResults]:
+        """Find the optimal parameters for self.cost_function.
+
+        Optimal parameters are found using `scipy.optimize.least_squares`
+        to fit the distributed row/col targets to `target_cost_distribution`.
+
+        NOTE: The achieved distribution is found by accessing self.achieved
+        distribution of the object this method is called on. The output of
+        this method shows the distribution and results for each individual TLD.
+
+        Parameters
+        ----------
+        distributions: MultiCostDistribution
+            distributions to use for the calibrations
+        running_log_path: os.PathLike,
+            path to a csv to log the model iterations and results
+        gm_params: GMCalibParams
+            defines the detailed parameters, see `GMCalibParams` documentation for more info 
+        *args,
+        **kwargs,
+        Returns
+        -------
+        dict[str | int, GravityModelCalibrateResults]:
+            containings the achieved distributions for each tld category. To access
+            the combined distribution use self.achieved_distribution
+
+        See Also
+        --------
+        `caf.distribute.furness.doubly_constrained_furness()`
+        `scipy.optimize.least_squares()`
+        `caf.distribute.gravity_model.multi_area.GMCalibParams`
+        """
+            
+        self._validate_running_log(running_log_path)
+        self._initialise_internal_params()
+
         params_len = len(distributions[0].function_params)
         ordered_init_params = []
 
         for dist in distributions:
+            self.cost_function.validate_params(dist.function_params)
             params = self._order_cost_params(dist.function_params)
             for val in params:
                 ordered_init_params.append(val)
@@ -534,10 +574,10 @@ def _calibrate(
         gravity_kwargs: dict[str, Any] = {
             "running_log_path": running_log_path,
             "cost_distributions": distributions,
-            "diff_step": diff_step,
+            "diff_step": gm_params.diff_step,
             "params_len": params_len,
-            "furness_jac": furness_jac,
-            "furness_tol": furness_tol,
+            "furness_jac": gm_params.furness_jac,
+            "furness_tol": gm_params.furness_tol,
         }
         optimise_cost_params = functools.partial(
             optimize.least_squares,
@@ -549,9 +589,9 @@ def _calibrate(
             ),
             jac=self._jacobian_function,
             verbose=verbose,
-            ftol=ftol,
-            xtol=xtol,
-            max_nfev=grav_max_iters,
+            ftol=gm_params.ftol,
+            xtol=gm_params.xtol,
+            max_nfev=gm_params.grav_max_iters,
             kwargs=gravity_kwargs | kwargs,
         )
         result = optimise_cost_params(x0=ordered_init_params)
@@ -568,14 +608,14 @@ def _calibrate(
         best_convergence = self.achieved_convergence
         best_params = result.x
 
-        if (not all(self.achieved_convergence) >= failure_tol) and default_retry:
+        if (not all(self.achieved_convergence) >= gm_params.failure_tol) and gm_params.default_retry:
             LOG.info(
                 "%sachieved a convergence of %s, "
                 "however the failure tolerance is set to %s. Trying again with "
                 "default cost parameters.",
                 self.unique_id,
                 self.achieved_convergence,
-                failure_tol,
+                gm_params.failure_tol,
             )
             self._attempt_id += 1
             ordered_init_params = self._order_cost_params(self.cost_function.default_params)
@@ -610,52 +650,6 @@ def _calibrate(
             results[dist.name] = result_i
         return results
 
-    def calibrate(
-        self,
-        distributions: MultiCostDistribution,
-        running_log_path: os.PathLike,
-        *args,
-        **kwargs,
-    ) -> dict[str | int, GravityModelCalibrateResults]:
-        """Find the optimal parameters for self.cost_function.
-
-        Optimal parameters are found using `scipy.optimize.least_squares`
-        to fit the distributed row/col targets to `target_cost_distribution`.
-
-        NOTE: The achieved distribution is found by accessing self.achieved
-        distribution of the object this method is called on. The output of
-        this method shows the distribution and results for each individual TLD.
-
-        Parameters
-        ----------
-        distributions: MultiCostDistribution
-            distributions to use for the calibrations
-        running_log_path: os.PathLike,
-            path to a csv to log the model iterations and results
-        *args,
-        **kwargs,
-        Returns
-        -------
-        dict[str | int, GravityModelCalibrateResults]:
-            An instance of GravityModelCalibrateResults containing the
-            results of this run.
-
-        See Also
-        --------
-        `caf.distribute.furness.doubly_constrained_furness()`
-        `scipy.optimize.least_squares()`
-        """
-        for dist in distributions:
-            self.cost_function.validate_params(dist.function_params)
-        self._validate_running_log(running_log_path)
-        self._initialise_internal_params()
-        return self._calibrate(  # type: ignore
-            distributions,
-            running_log_path,
-            *args,
-            **kwargs,
-        )
-
     def _jacobian_function(
         self,
         init_params: list[float],