diff --git a/lib/bcoin/block.js b/lib/bcoin/block.js
index d7a595bd..e4f9fd2f 100644
--- a/lib/bcoin/block.js
+++ b/lib/bcoin/block.js
@@ -21,6 +21,7 @@ function Block(data, subtype) {
   this.flags = data.flags || [];
   this._network = data._network || false;
   this._raw = data._raw || null;
+  this._size = data._size || 0;
 
   // List of matched TXs
   this.tx = [];
@@ -80,6 +81,10 @@ Block.prototype.render = function render() {
   return bcoin.protocol.framer.block(this, this.subtype);
 };
 
+Block.prototype.size = function render() {
+  return this._size || this.render().length;
+};
+
 Block.prototype.hasTX = function hasTX(hash) {
   return this.tx.indexOf(hash) !== -1;
 };
@@ -172,9 +177,11 @@ Block.prototype._checkBlock = function checkBlock() {
   if (this.ts > (Date.now() / 1000) + 2 * 60 * 60)
     return false;
 
-  // Size of all txs cant be bigger than MAX_BLOCK_SIZE
-  if (this.txs.length > bcoin.protocol.constants.block.maxSize)
+  // Size can't be bigger than MAX_BLOCK_SIZE
+  if (this.txs.length > constants.block.maxSize
+      || this.size() > constants.block.maxSize) {
     return false;
+  }
 
   // First TX must be a coinbase
   if (!this.txs.length ||
diff --git a/lib/bcoin/protocol/parser.js b/lib/bcoin/protocol/parser.js
index 160f2d6a..ebc58731 100644
--- a/lib/bcoin/protocol/parser.js
+++ b/lib/bcoin/protocol/parser.js
@@ -222,7 +222,8 @@ Parser.prototype.parseMerkleBlock = function parseMerkleBlock(p) {
     totalTX: readU32(p, 80),
     hashes: hashes,
     flags: flags,
-    _raw: p.slice(0, 80)
+    _raw: p.slice(0, 80),
+    _size: p.length
   };
 };
 
@@ -289,7 +290,8 @@ Parser.prototype.parseBlock = function parseBlock(p) {
     nonce: readU32(p, 76),
     totalTX: totalTX,
     txs: txs,
-    _raw: p.slice(0, 80)
+    _raw: p.slice(0, 80),
+    _size: p.length
   };
 };
 
@@ -381,7 +383,8 @@ Parser.prototype.parseTX = function parseTX(p) {
     inputs: txIn,
     outputs: txOut,
     lock: readU32(p, off),
-    _off: off + 4
+    _off: off + 4,
+    _size: p.length
   };
 };
 
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index 422e1148..cde33766 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -23,6 +23,7 @@ function TX(data, block) {
   this._hash = null;
   this._raw = data._raw || null;
   this._network = data._network || false;
+  this._size = data._size || 0;
   this._lock = this.lock;
 
   if (data.inputs) {
@@ -66,6 +67,10 @@ TX.prototype.render = function render() {
   return bcoin.protocol.framer.tx(this);
 };
 
+TX.prototype.size = function size() {
+  return this._size || this.render().length;
+};
+
 TX.prototype.input = function input(i, index) {
   this._input(i, index);
   return this;