diff --git a/species/plot/plot_spectrum.py b/species/plot/plot_spectrum.py
index 65b518a..f78ad28 100644
--- a/species/plot/plot_spectrum.py
+++ b/species/plot/plot_spectrum.py
@@ -58,6 +58,7 @@ def plot_spectrum(
     grid_hspace: float = 0.1,
     inc_model_name: bool = False,
     units: Tuple[str, str] = ("um", "W m-2 um-1"),
+    font_size: Optional[Dict[str, float]] = None,
 ) -> mpl.figure.Figure:
     """
     Function for plotting a spectral energy distribution and combining
@@ -173,6 +174,13 @@ def plot_spectrum(
         Tuple with the wavelength and flux units. Supported
         units can be found in the docstring of
         :func:`~species.util.data_util.convert_units`.
+    font_size : dict(str, float), None
+        Dictionary with the font sizes. The keys can be set to
+        'xlabel', 'ylabel', 'title', and 'legend'. The values
+        should be set to the font sizes. Default font size are
+        used when setting the argument to ``None``. The legend
+        font size is not used if it is also set with the
+        ``legend`` parameter.
 
     Returns
     -------
@@ -413,35 +421,52 @@ def plot_spectrum(
     else:
         y_unit = units[1]
 
+    if font_size is None:
+        font_size = {}
+
+    if "xlabel" not in font_size:
+        font_size["xlabel"] = 11.
+
+    if "ylabel" not in font_size:
+        font_size["ylabel"] = 11.
+
+    if "title" not in font_size:
+        font_size["title"] = 13.
+
+    if "legend" not in font_size:
+        font_size["legend"] = 9.
+
+    print(f"Font sizes: {font_size}")
+
     if residuals is not None and filters is not None:
         ax1.set_xlabel("")
         ax2.set_xlabel("")
-        ax3.set_xlabel(x_label, fontsize=11)
+        ax3.set_xlabel(x_label, fontsize=font_size["xlabel"])
 
     elif residuals is not None:
         ax1.set_xlabel("")
-        ax3.set_xlabel(x_label, fontsize=11)
+        ax3.set_xlabel(x_label, fontsize=font_size["xlabel"])
 
     elif filters is not None:
-        ax1.set_xlabel(x_label, fontsize=11)
+        ax1.set_xlabel(x_label, fontsize=font_size["xlabel"])
         ax2.set_xlabel("")
 
     else:
-        ax1.set_xlabel(x_label, fontsize=11)
+        ax1.set_xlabel(x_label, fontsize=font_size["xlabel"])
 
     if filters is not None:
-        ax2.set_ylabel(r"$T_\lambda$", fontsize=11)
+        ax2.set_ylabel(r"$T_\lambda$", fontsize=font_size["ylabel"])
 
     if residuals is not None:
         if quantity == "flux density":
-            ax3.set_ylabel(r"$\Delta$$F_\lambda$ ($\sigma$)", fontsize=11)
+            ax3.set_ylabel(r"$\Delta$$F_\lambda$ ($\sigma$)", fontsize=font_size["ylabel"])
 
         elif quantity == "flux":
-            ax3.set_ylabel(r"$\Delta$$F_\lambda$ ($\sigma$)", fontsize=11)
+            ax3.set_ylabel(r"$\Delta$$F_\lambda$ ($\sigma$)", fontsize=font_size["ylabel"])
 
     if quantity == "magnitude":
         scaling = 1.0
-        ax1.set_ylabel("Contrast (mag)", fontsize=11)
+        ax1.set_ylabel("Contrast (mag)", fontsize=font_size["ylabel"])
 
         if ylim is not None:
             ax1.set_ylim(ylim[0], ylim[1])
@@ -480,7 +505,7 @@ def plot_spectrum(
                         + r"}$ W m$^{-2}$)"
                     )
 
-            ax1.set_ylabel(ylabel, fontsize=11)
+            ax1.set_ylabel(ylabel, fontsize=font_size["ylabel"])
             ax1.set_ylim(ylim[0] / scaling, ylim[1] / scaling)
 
             if ylim[0] < 0.0:
@@ -492,11 +517,11 @@ def plot_spectrum(
             if quantity == "flux density":
                 ax1.set_ylabel(
                     rf"$F_\lambda$ ({y_unit})",
-                    fontsize=11,
+                    fontsize=font_size["ylabel"],
                 )
 
             elif quantity == "flux":
-                ax1.set_ylabel(r"$\lambda$$F_\lambda$ (W m$^{-2}$)", fontsize=11)
+                ax1.set_ylabel(r"$\lambda$$F_\lambda$ (W m$^{-2}$)", fontsize=font_size["ylabel"])
 
             scaling = 1.0
 
@@ -1337,9 +1362,9 @@ def plot_spectrum(
 
     if title is not None:
         if filters:
-            ax2.set_title(title, y=1.02, fontsize=13)
+            ax2.set_title(title, y=1.02, fontsize=font_size["title"])
         else:
-            ax1.set_title(title, y=1.02, fontsize=13)
+            ax1.set_title(title, y=1.02, fontsize=font_size["title"])
 
     handles, labels = ax1.get_legend_handles_labels()
 
@@ -1364,10 +1389,13 @@ def plot_spectrum(
                         model_handles,
                         model_labels,
                         loc=legend[0],
-                        fontsize=10.0,
+                        fontsize=font_size["legend"],
                         frameon=False,
                     )
                 else:
+                    if "fontsize" not in legend[0]:
+                        legend[0]["fontsize"] = font_size["legend"]
+
                     leg_1 = ax1.legend(model_handles, model_labels, **legend[0])
 
             else:
@@ -1379,19 +1407,25 @@ def plot_spectrum(
                         data_handles,
                         data_labels,
                         loc=legend[1],
-                        fontsize=8,
+                        fontsize=font_size["legend"],
                         frameon=False,
                     )
                 else:
+                    if "fontsize" not in legend[1]:
+                        legend[1]["fontsize"] = font_size["legend"]
+
                     ax1.legend(data_handles, data_labels, **legend[1])
 
             if leg_1 is not None:
                 ax1.add_artist(leg_1)
 
         elif isinstance(legend, (str, tuple)):
-            ax1.legend(loc=legend, fontsize=8, frameon=False)
+            ax1.legend(loc=legend, fontsize=font_size["legend"], frameon=False)
 
         else:
+            if "fontsize" not in legend:
+                legend["fontsize"] = font_size["legend"]
+
             ax1.legend(**legend)
 
     # if scale[0] == "log":