diff --git a/crates/primitives-traits/src/block/body.rs b/crates/primitives-traits/src/block/body.rs
index 9b703c0d2f..14941ffed0 100644
--- a/crates/primitives-traits/src/block/body.rs
+++ b/crates/primitives-traits/src/block/body.rs
@@ -6,7 +6,7 @@ use alloy_consensus::{BlockHeader, Transaction, TxType};
 use alloy_eips::{eip4895::Withdrawal, eip7685::Requests};
 use alloy_primitives::{Address, B256};
 
-use crate::Block;
+use crate::{Block, InMemorySize};
 
 /// Abstraction for block's body.
 pub trait BlockBody:
@@ -22,6 +22,7 @@ pub trait BlockBody:
     + for<'de> serde::Deserialize<'de>
     + alloy_rlp::Encodable
     + alloy_rlp::Decodable
+    + InMemorySize
 {
     /// Ordered list of signed transactions as committed in block.
     // todo: requires trait for signed transaction
@@ -93,7 +94,4 @@ pub trait BlockBody:
     fn blob_versioned_hashes(&self) -> Vec<&B256> {
         self.blob_versioned_hashes_iter().collect()
     }
-
-    /// Calculates a heuristic for the in-memory size of the [`BlockBody`].
-    fn size(&self) -> usize;
 }
diff --git a/crates/primitives-traits/src/block/mod.rs b/crates/primitives-traits/src/block/mod.rs
index 185b61e978..cfc9e9a550 100644
--- a/crates/primitives-traits/src/block/mod.rs
+++ b/crates/primitives-traits/src/block/mod.rs
@@ -8,7 +8,7 @@ use alloc::{fmt, vec::Vec};
 use alloy_primitives::{Address, B256};
 use reth_codecs::Compact;
 
-use crate::{BlockBody, BlockHeader, FullBlockHeader};
+use crate::{BlockBody, BlockHeader, FullBlockHeader, InMemorySize};
 
 /// Helper trait that unifies all behaviour required by block to support full node operations.
 pub trait FullBlock: Block<Header: Compact> + Compact {}
@@ -32,6 +32,7 @@ pub trait Block:
     + for<'a> serde::Deserialize<'a>
     + From<(Self::Header, Self::Body)>
     + Into<(Self::Header, Self::Body)>
+    + InMemorySize
 {
     /// Header part of the block.
     type Header: BlockHeader;
@@ -104,7 +105,4 @@ pub trait Block:
     // todo: can be default impl if sealed block type is made generic over header and body and
     // migrated to alloy
     fn with_recovered_senders(self) -> Option<Self::BlockWithSenders<Self>>;
-
-    /// Calculates a heuristic for the in-memory size of the [`Block`].
-    fn size(&self) -> usize;
 }
diff --git a/crates/primitives-traits/src/transaction/mod.rs b/crates/primitives-traits/src/transaction/mod.rs
index 7fd0ec88b3..d5061ca390 100644
--- a/crates/primitives-traits/src/transaction/mod.rs
+++ b/crates/primitives-traits/src/transaction/mod.rs
@@ -7,6 +7,8 @@ use alloy_primitives::{TxKind, B256};
 use reth_codecs::Compact;
 use serde::{Deserialize, Serialize};
 
+use crate::InMemorySize;
+
 pub mod signed;
 
 #[allow(dead_code)]
@@ -26,6 +28,7 @@ pub trait Transaction:
     + alloy_rlp::Decodable
     + for<'de> Deserialize<'de>
     + alloy_consensus::Transaction
+    + InMemorySize
     + MaybeArbitrary
 {
     /// Heavy operation that return signature hash over rlp encoded transaction.
@@ -45,9 +48,6 @@ pub trait Transaction:
     /// This encodes the transaction _without_ the signature, and is only suitable for creating a
     /// hash intended for signing.
     fn encode_without_signature(&self, out: &mut dyn bytes::BufMut);
-
-    /// Calculates a heuristic for the in-memory size of the [Transaction].
-    fn size(&self) -> usize;
 }
 
 #[cfg(not(feature = "arbitrary"))]