diff --git a/lib/latex_to_png.rb b/lib/latex_to_png.rb
index <HASH>..<HASH> 100644
--- a/lib/latex_to_png.rb
+++ b/lib/latex_to_png.rb
@@ -40,7 +40,13 @@ module LatexToPng
 		attr_accessor :dirname , :filename, :basename, :png_file, :template_path
 
     def size_in_points size_in_pixels
-      Sizes.invert[size_in_pixels]
+      size = Sizes.invert[size_in_pixels]
+      if size.nil?
+        size_in_points "#{size_in_pixels.to_i + 1}px"
+
+      else
+        size
+      end
     end
 
 		def initialize opts={ filename: nil, formula: nil, template_path: nil, size_in_pixels: nil }
diff --git a/spec/convert_spec.rb b/spec/convert_spec.rb
index <HASH>..<HASH> 100644
--- a/spec/convert_spec.rb
+++ b/spec/convert_spec.rb
@@ -15,6 +15,15 @@ describe "" do
 
 	end
 
+	it "convert.size_in_points de pixels para pontos arredondadndo" do 
+	
+		image = LatexToPng::Convert.new(filename: "#{ROOT_DIR_SPEC}/support/flux.tex")
+		
+		expect(image.size_in_points("18px")).to eq "14pt"
+
+	end
+
+
 	it "dirname do arquivo" do 
 	
 		image = LatexToPng::Convert.new(filename: "#{ROOT_DIR_SPEC}/support/flux.tex")
ADD size in points rounding to up