diff --git a/src/cryptonum/builder.rs b/src/cryptonum/builder.rs
index 5ef94dc..ff5a622 100644
--- a/src/cryptonum/builder.rs
+++ b/src/cryptonum/builder.rs
@@ -259,6 +259,14 @@ macro_rules! construct_unsigned {
 
 
         impl CryptoNumSerialization for $type {
+            fn bit_size(&self) -> usize {
+                $count * 64
+            }
+
+            fn byte_size(&self) -> usize {
+                $count * 8
+            }
+
             fn to_bytes(&self) -> Vec<u8> {
                 let mut res = Vec::with_capacity($count * 8);
                 for x in self.contents.iter() {
diff --git a/src/cryptonum/traits.rs b/src/cryptonum/traits.rs
index 4209c39..9a16888 100644
--- a/src/cryptonum/traits.rs
+++ b/src/cryptonum/traits.rs
@@ -32,6 +32,10 @@ pub trait CryptoNumBase {
 }
 
 pub trait CryptoNumSerialization {
+    /// The number of bits used when this number is serialized.
+    fn bit_size(&self) -> usize;
+    /// The number of bytes used when this number is serialized.
+    fn byte_size(&self) -> usize;
     /// Convert a number to a series of bytes, in standard order (most to
     /// least significant)
     fn to_bytes(&self) -> Vec<u8>;