diff --git a/bench/coins.js b/bench/coins.js
index c8d31d0a..44d6b000 100644
--- a/bench/coins.js
+++ b/bench/coins.js
@@ -7,7 +7,7 @@ var bench = require('./bench');
 
 var raw = fs.readFileSync(__dirname + '/../test/data/wtx.hex', 'utf8');
 var wtx = TX.fromRaw(raw.trim(), 'hex');
-var coins = Coins.fromTX(wtx);
+var coins = Coins.fromTX(wtx, 1);
 var i, j, end, hash;
 
 end = bench('serialize');
diff --git a/lib/coins/coins.js b/lib/coins/coins.js
index 70c19aa9..c10412df 100644
--- a/lib/coins/coins.js
+++ b/lib/coins/coins.js
@@ -12,7 +12,8 @@ var constants = require('../protocol/constants');
 var Coin = require('../primitives/coin');
 var Output = require('../primitives/output');
 var BufferReader = require('../utils/reader');
-var BufferWriter = require('../utils/writer');
+var StaticWriter = require('../utils/staticwriter');
+var encoding = require('../utils/encoding');
 var compressor = require('./compress');
 var compress = compressor.compress;
 var decompress = compressor.decompress;
@@ -306,18 +307,17 @@ Coins.prototype.isEmpty = function isEmpty() {
  */
 
 /**
- * Write the coins object to writer.
- * @param {BufferWriter} bw
- * @returns {BufferWriter}
+ * Calculate header code.
+ * @param {Number} len
+ * @param {Number} size
+ * @returns {Number}
  */
 
-Coins.prototype.toWriter = function toWriter(bw) {
-  var len = this.length();
-  var size = Math.floor((len + 5) / 8);
+Coins.prototype.header = function header(len, size) {
   var first = this.isUnspent(0);
   var second = this.isUnspent(1);
   var offset = 0;
-  var i, j, code, ch, output;
+  var code;
 
   // Throw if we're fully spent.
   assert(len !== 0, 'Cannot serialize fully-spent coins.');
@@ -341,6 +341,22 @@ Coins.prototype.toWriter = function toWriter(bw) {
   if (second)
     code += 4;
 
+  return code;
+};
+
+/**
+ * Serialize the coins object.
+ * @returns {Buffer}
+ */
+
+Coins.prototype.toRaw = function toRaw() {
+  var len = this.length();
+  var size = Math.floor((len + 5) / 8);
+  var code = this.header(len, size);
+  var total = this.getSize(len, size, code);
+  var bw = new StaticWriter(total);
+  var i, j, ch, output;
+
   // Write headers.
   bw.writeVarint(this.version);
   bw.writeU32(this.height);
@@ -366,27 +382,49 @@ Coins.prototype.toWriter = function toWriter(bw) {
     output.toWriter(bw);
   }
 
-  return bw;
+  return bw.render();
 };
 
 /**
- * Serialize the coins object.
- * @returns {Buffer}
+ * Calculate coins size.
+ * @param {Number} code
+ * @param {Number} size
+ * @param {Number} len
+ * @returns {Number}
  */
 
-Coins.prototype.toRaw = function toRaw() {
-  return this.toWriter(new BufferWriter()).render();
+Coins.prototype.getSize = function getSize(len, size, code) {
+  var total = 0;
+  var i, output;
+
+  total += encoding.sizeVarint(this.version);
+  total += 4;
+  total += encoding.sizeVarint(code);
+  total += size;
+
+  // Write the compressed outputs.
+  for (i = 0; i < len; i++) {
+    output = this.outputs[i];
+
+    if (!output || output.spent)
+      continue;
+
+    total += output.getSize();
+  }
+
+  return total;
 };
 
 /**
- * Inject data from buffer reader.
+ * Inject data from serialized coins.
  * @private
- * @param {BufferReader} br
+ * @param {Buffer} data
  * @param {Hash} hash
  * @returns {Coins}
  */
 
-Coins.prototype.fromReader = function fromReader(br, hash) {
+Coins.prototype.fromRaw = function fromRaw(data, hash) {
+  var br = new BufferReader(data);
   var first = null;
   var second = null;
   var i, j, code, size, offset, ch;
@@ -437,18 +475,6 @@ Coins.prototype.fromReader = function fromReader(br, hash) {
   return this;
 };
 
-/**
- * Inject data from serialized coins.
- * @private
- * @param {Buffer} data
- * @param {Hash} hash
- * @returns {Coins}
- */
-
-Coins.prototype.fromRaw = function fromRaw(data, hash) {
-  return this.fromReader(new BufferReader(data), hash);
-};
-
 /**
  * Parse a single serialized coin.
  * @param {Buffer} data
@@ -519,17 +545,6 @@ Coins.parseCoin = function parseCoin(data, hash, index) {
   }
 };
 
-/**
- * Instantiate coins from a buffer reader.
- * @param {Buffer} data
- * @param {Hash} hash - Transaction hash.
- * @returns {Coins}
- */
-
-Coins.fromReader = function fromReader(br, hash) {
-  return new Coins().fromReader(br, hash);
-};
-
 /**
  * Instantiate coins from a buffer.
  * @param {Buffer} data
@@ -668,6 +683,18 @@ CoinEntry.prototype.toOutput = function toOutput() {
   return this.output;
 };
 
+/**
+ * Calculate coin entry size.
+ * @returns {Number}
+ */
+
+CoinEntry.prototype.getSize = function getSize() {
+  if (!this.raw)
+    return compress.size(this.output);
+
+  return this.size;
+};
+
 /**
  * Slice off the part of the buffer
  * relevant to this particular coin.
diff --git a/lib/coins/compress.js b/lib/coins/compress.js
index 4467c720..1f842e73 100644
--- a/lib/coins/compress.js
+++ b/lib/coins/compress.js
@@ -8,6 +8,7 @@
 
 var assert = require('assert');
 var ec = require('../crypto/ec');
+var encoding = require('../utils/encoding');
 
 /*
  * Constants
@@ -115,6 +116,33 @@ function decompressScript(script, br) {
   return script;
 }
 
+/**
+ * Calculate script size.
+ * @returns {Number}
+ */
+
+function sizeScript(script) {
+  var size, data;
+
+  if (script.isPubkeyhash(true))
+    return 21;
+
+  if (script.isScripthash())
+    return 21;
+
+  if (script.isPubkey(true)) {
+    data = script.code[0].data;
+    if (publicKeyVerify(data))
+      return 33;
+  }
+
+  size = 0;
+  size += encoding.sizeVarint(script.raw.length + COMPRESS_TYPES);
+  size += script.raw.length;
+
+  return size;
+}
+
 /**
  * Compress an output.
  * @param {Output} output
@@ -139,6 +167,18 @@ function decompressOutput(output, br) {
   return output;
 }
 
+/**
+ * Calculate output size.
+ * @returns {Number}
+ */
+
+function sizeOutput(output) {
+  var size = 0;
+  size += encoding.sizeVarint(output.value);
+  size += sizeScript(output.script);
+  return size;
+}
+
 /**
  * Compress an output.
  * @param {Coin} coin
@@ -356,6 +396,7 @@ function decompressKey(key) {
 exports.compress = {
   output: compressOutput,
   coin: compressCoin,
+  size: sizeOutput,
   script: compressScript,
   value: compressValue,
   key: compressKey
diff --git a/lib/coins/undocoins.js b/lib/coins/undocoins.js
index b00c7706..022ed55f 100644
--- a/lib/coins/undocoins.js
+++ b/lib/coins/undocoins.js
@@ -8,7 +8,8 @@
 
 var assert = require('assert');
 var BufferReader = require('../utils/reader');
-var BufferWriter = require('../utils/writer');
+var StaticWriter = require('../utils/staticwriter');
+var encoding = require('../utils/encoding');
 var Output = require('../primitives/output');
 var Coins = require('./coins');
 var compressor = require('./compress');
@@ -43,13 +44,33 @@ UndoCoins.prototype.push = function push(entry) {
   this.items.push(undo);
 };
 
+/**
+ * Calculate undo coins size.
+ * @returns {Number}
+ */
+
+UndoCoins.prototype.getSize = function getSize() {
+  var size = 0;
+  var i, coin;
+
+  size += 4;
+
+  for (i = 0; i < this.items.length; i++) {
+    coin = this.items[i];
+    size += coin.getSize();
+  }
+
+  return size;
+};
+
 /**
  * Serialize all undo coins.
  * @returns {Buffer}
  */
 
 UndoCoins.prototype.toRaw = function toRaw() {
-  var bw = new BufferWriter();
+  var size = this.getSize();
+  var bw = new StaticWriter(size);
   var i, coin;
 
   bw.writeU32(this.items.length);
@@ -184,6 +205,33 @@ UndoCoin.prototype.toOutput = function toOutput() {
   return this.output;
 };
 
+/**
+ * Calculate undo coin size.
+ * @returns {Number}
+ */
+
+UndoCoin.prototype.getSize = function getSize() {
+  var height = this.height;
+  var size = 0;
+
+  if (height === -1)
+    height = 0;
+
+  size += encoding.sizeVarint(height * 2 + (this.coinbase ? 1 : 0));
+
+  if (this.height !== -1)
+    size += encoding.sizeVarint(this.version);
+
+  if (this.entry) {
+    // Cached from spend.
+    size += this.entry.getSize();
+  } else {
+    size += compress.size(this.output);
+  }
+
+  return size;
+};
+
 /**
  * Write the undo coin to a buffer writer.
  * @param {BufferWriter} bw
@@ -220,7 +268,8 @@ UndoCoin.prototype.toWriter = function toWriter(bw) {
  */
 
 UndoCoin.prototype.toRaw = function toRaw() {
-  return this.toWriter(new BufferWriter()).render();
+  var size = this.getSize();
+  return this.toWriter(new StaticWriter(size)).render();
 };
 
 /**
diff --git a/lib/primitives/abstractblock.js b/lib/primitives/abstractblock.js
index 08be9641..78e7c514 100644
--- a/lib/primitives/abstractblock.js
+++ b/lib/primitives/abstractblock.js
@@ -13,7 +13,7 @@ var util = require('../utils/util');
 var crypto = require('../crypto/crypto');
 var btcutils = require('../btc/utils');
 var VerifyResult = require('../btc/errors').VerifyResult;
-var BufferWriter = require('../utils/writer');
+var StaticWriter = require('../utils/staticwriter');
 var InvItem = require('./invitem');
 
 /**
@@ -160,7 +160,7 @@ AbstractBlock.prototype.hash = function hash(enc) {
  */
 
 AbstractBlock.prototype.abbr = function abbr() {
-  var bw = new BufferWriter();
+  var bw = new StaticWriter(80);
   bw.writeU32(this.version);
   bw.writeHash(this.prevBlock);
   bw.writeHash(this.merkleRoot);
diff --git a/lib/primitives/input.js b/lib/primitives/input.js
index 99783022..afa18e4e 100644
--- a/lib/primitives/input.js
+++ b/lib/primitives/input.js
@@ -14,7 +14,7 @@ var Network = require('../protocol/network');
 var Script = require('../script/script');
 var Witness = require('../script/witness');
 var Outpoint = require('./outpoint');
-var BufferWriter = require('../utils/writer');
+var StaticWriter = require('../utils/staticwriter');
 var BufferReader = require('../utils/reader');
 
 /**
@@ -335,7 +335,8 @@ Input.prototype.getSize = function getSize() {
  */
 
 Input.prototype.toRaw = function toRaw() {
-  return this.toWriter(new BufferWriter()).render();
+  var size = this.getSize();
+  return this.toWriter(new StaticWriter(size)).render();
 };
 
 /**
diff --git a/lib/primitives/outpoint.js b/lib/primitives/outpoint.js
index 335560fd..e2687390 100644
--- a/lib/primitives/outpoint.js
+++ b/lib/primitives/outpoint.js
@@ -9,7 +9,7 @@
 var util = require('../utils/util');
 var assert = require('assert');
 var constants = require('../protocol/constants');
-var BufferWriter = require('../utils/writer');
+var StaticWriter = require('../utils/writer');
 var BufferReader = require('../utils/reader');
 
 /**
@@ -124,7 +124,7 @@ Outpoint.prototype.getSize = function getSize() {
  */
 
 Outpoint.prototype.toRaw = function toRaw() {
-  return this.toWriter(new BufferWriter()).render();
+  return this.toWriter(new StaticWriter(36)).render();
 };
 
 /**
diff --git a/lib/primitives/output.js b/lib/primitives/output.js
index f4015add..aa3195b5 100644
--- a/lib/primitives/output.js
+++ b/lib/primitives/output.js
@@ -13,7 +13,7 @@ var btcutils = require('../btc/utils');
 var Amount = require('../btc/amount');
 var Network = require('../protocol/network');
 var Script = require('../script/script');
-var BufferWriter = require('../utils/writer');
+var StaticWriter = require('../utils/staticwriter');
 var BufferReader = require('../utils/reader');
 var assert = require('assert');
 
@@ -246,7 +246,8 @@ Output.prototype.toWriter = function toWriter(bw) {
  */
 
 Output.prototype.toRaw = function toRaw() {
-  return this.toWriter(new BufferWriter()).render();
+  var size = this.getSize();
+  return this.toWriter(new StaticWriter(size)).render();
 };
 
 /**
diff --git a/lib/primitives/tx.js b/lib/primitives/tx.js
index 4706525a..371b95dd 100644
--- a/lib/primitives/tx.js
+++ b/lib/primitives/tx.js
@@ -9,6 +9,7 @@
 
 var assert = require('assert');
 var util = require('../utils/util');
+var encoding = require('../utils/encoding');
 var co = require('../utils/co');
 var crypto = require('../crypto/crypto');
 var btcutils = require('../btc/utils');
@@ -17,6 +18,7 @@ var constants = require('../protocol/constants');
 var Network = require('../protocol/network');
 var Script = require('../script/script');
 var BufferWriter = require('../utils/writer');
+var StaticWriter = require('../utils/staticwriter');
 var VerifyResult = require('../btc/errors').VerifyResult;
 var Input = require('./input');
 var Output = require('./output');
@@ -432,8 +434,7 @@ TX.prototype.signatureHash = function signatureHash(index, prev, value, type, ve
  */
 
 TX.prototype.signatureHashV0 = function signatureHashV0(index, prev, type) {
-  var i, input, output;
-  var bw = new BufferWriter();
+  var i, size, bw, input, output;
   var hashType = type & 0x1f;
 
   if (hashType === constants.hashType.SINGLE) {
@@ -446,8 +447,14 @@ TX.prototype.signatureHashV0 = function signatureHashV0(index, prev, type) {
   // Remove all code separators.
   prev = prev.removeSeparators();
 
+  // Calculate buffer size.
+  size = this.hashSize(index, prev, type);
+
+  bw = new StaticWriter(size);
+
   bw.writeU32(this.version);
 
+  // Serialize inputs.
   if (type & constants.hashType.ANYONECANPAY) {
     bw.writeVarint(1);
 
@@ -482,48 +489,56 @@ TX.prototype.signatureHashV0 = function signatureHashV0(index, prev, type) {
       bw.writeVarint(0);
 
       // Sequences are 0 if NONE or SINGLE.
-      if (hashType === constants.hashType.NONE
-          || hashType === constants.hashType.SINGLE) {
-        bw.writeU32(0);
-      } else {
-        bw.writeU32(input.sequence);
+      switch (hashType) {
+        case constants.hashType.NONE:
+        case constants.hashType.SINGLE:
+          bw.writeU32(0);
+          break;
+        default:
+          bw.writeU32(input.sequence);
+          break;
       }
     }
   }
 
-  if (hashType === constants.hashType.NONE) {
-    // No outputs if NONE.
-    bw.writeVarint(0);
-  } else if (hashType === constants.hashType.SINGLE) {
-    // Drop all outputs after the
-    // current input index if SINGLE.
-    bw.writeVarint(index + 1);
+  // Serialize outputs.
+  switch (hashType) {
+    case constants.hashType.NONE:
+      // No outputs if NONE.
+      bw.writeVarint(0);
+      break;
+    case constants.hashType.SINGLE:
+      // Drop all outputs after the
+      // current input index if SINGLE.
+      bw.writeVarint(index + 1);
 
-    for (i = 0; i < index + 1; i++) {
-      output = this.outputs[i];
+      for (i = 0; i < index + 1; i++) {
+        output = this.outputs[i];
 
-      // Regular serialization if
-      // at current input index.
-      if (i === index) {
+        // Regular serialization if
+        // at current input index.
+        if (i === index) {
+          bw.write64(output.value);
+          bw.writeVarBytes(output.script.toRaw());
+          continue;
+        }
+
+        // Null all outputs not at
+        // current input index.
+        bw.write64(-1);
+        bw.writeVarint(0);
+      }
+      break;
+    default:
+      // Regular output serialization if ALL.
+      bw.writeVarint(this.outputs.length);
+
+      for (i = 0; i < this.outputs.length; i++) {
+        output = this.outputs[i];
         bw.write64(output.value);
         bw.writeVarBytes(output.script.toRaw());
-        continue;
       }
-
-      // Null all outputs not at
-      // current input index.
-      bw.write64(-1);
-      bw.writeVarint(0);
-    }
-  } else {
-    // Regular output serialization if ALL.
-    bw.writeVarint(this.outputs.length);
-
-    for (i = 0; i < this.outputs.length; i++) {
-      output = this.outputs[i];
-      bw.write64(output.value);
-      bw.writeVarBytes(output.script.toRaw());
-    }
+      break;
   }
 
   bw.writeU32(this.locktime);
@@ -534,6 +549,57 @@ TX.prototype.signatureHashV0 = function signatureHashV0(index, prev, type) {
   return crypto.hash256(bw.render());
 };
 
+/**
+ * Calculate sighash size.
+ * @private
+ * @param {Number} index
+ * @param {Script} prev
+ * @param {Number} type
+ * @returns {Number}
+ */
+
+TX.prototype.hashSize = function hashSize(index, prev, type) {
+  var size = 0;
+  var i, output;
+
+  size += 4;
+
+  if (type & constants.hashType.ANYONECANPAY) {
+    size += 1;
+    size += 36;
+    size += prev.getVarSize();
+    size += 4;
+  } else {
+    size += encoding.sizeVarint(this.inputs.length);
+    size += 41 * (this.inputs.length - 1);
+    size += 36;
+    size += prev.getVarSize();
+    size += 4;
+  }
+
+  switch (type & 0x1f) {
+    case constants.hashType.NONE:
+      size += 1;
+      break;
+    case constants.hashType.SINGLE:
+      size += encoding.sizeVarint(index + 1);
+      size += 9 * index;
+      size += this.outputs[index].getSize();
+      break;
+    default:
+      size += encoding.sizeVarint(this.outputs.length);
+      for (i = 0; i < this.outputs.length; i++) {
+        output = this.outputs[i];
+        size += output.getSize();
+      }
+      break;
+  }
+
+  size += 8;
+
+  return size;
+};
+
 /**
  * Witness sighashing -- O(n).
  * @private
@@ -544,13 +610,13 @@ TX.prototype.signatureHashV0 = function signatureHashV0(index, prev, type) {
  */
 
 TX.prototype.signatureHashV1 = function signatureHashV1(index, prev, value, type) {
-  var i, bw, input, output, prevouts, sequences, outputs;
+  var i, bw, size, input, output, prevouts, sequences, outputs;
 
   if (!(type & constants.hashType.ANYONECANPAY)) {
     if (this._hashPrevouts) {
       prevouts = this._hashPrevouts;
     } else {
-      bw = new BufferWriter();
+      bw = new StaticWriter(this.inputs.length * 36);
 
       for (i = 0; i < this.inputs.length; i++) {
         input = this.inputs[i];
@@ -572,7 +638,7 @@ TX.prototype.signatureHashV1 = function signatureHashV1(index, prev, value, type
     if (this._hashSequence) {
       sequences = this._hashSequence;
     } else {
-      bw = new BufferWriter();
+      bw = new StaticWriter(this.inputs.length * 4);
 
       for (i = 0; i < this.inputs.length; i++) {
         input = this.inputs[i];
@@ -593,7 +659,14 @@ TX.prototype.signatureHashV1 = function signatureHashV1(index, prev, value, type
     if (this._hashOutputs) {
       outputs = this._hashOutputs;
     } else {
-      bw = new BufferWriter();
+      size = 0;
+
+      for (i = 0; i < this.outputs.length; i++) {
+        output = this.outputs[i];
+        size += output.getSize();
+      }
+
+      bw = new StaticWriter(size);
 
       for (i = 0; i < this.outputs.length; i++) {
         output = this.outputs[i];
@@ -614,7 +687,8 @@ TX.prototype.signatureHashV1 = function signatureHashV1(index, prev, value, type
 
   input = this.inputs[index];
 
-  bw = new BufferWriter();
+  size = 156 + prev.getVarSize();
+  bw = new StaticWriter(size);
 
   bw.writeU32(this.version);
   bw.writeBytes(prevouts);
diff --git a/lib/script/opcode.js b/lib/script/opcode.js
index dc11600d..2e568fcd 100644
--- a/lib/script/opcode.js
+++ b/lib/script/opcode.js
@@ -13,7 +13,6 @@ var constants = require('../protocol/constants');
 var util = require('../utils/util');
 var encoding = require('./encoding');
 var BufferReader = require('../utils/reader');
-var BufferWriter = require('../utils/writer');
 var StaticWriter = require('../utils/staticwriter');
 var opcodes = constants.opcodes;
 
diff --git a/lib/script/witness.js b/lib/script/witness.js
index 3b09ad6e..b4651d07 100644
--- a/lib/script/witness.js
+++ b/lib/script/witness.js
@@ -19,9 +19,8 @@ var Script = require('./script');
 var encoding = require('./encoding');
 var enc = require('../utils/encoding');
 var Opcode = require('./opcode');
-var BufferWriter = require('../utils/writer');
-var StaticWriter = require('../utils/staticwriter');
 var BufferReader = require('../utils/reader');
+var StaticWriter = require('../utils/staticwriter');
 var Address = require('../primitives/address');
 var Stack = require('./stack');
 
diff --git a/lib/utils/staticwriter.js b/lib/utils/staticwriter.js
index aac3ee9c..5fa8e23e 100644
--- a/lib/utils/staticwriter.js
+++ b/lib/utils/staticwriter.js
@@ -1,6 +1,5 @@
 /*!
- * writer.js - buffer writer for bcoin
- * Copyright (c) 2014-2015, Fedor Indutny (MIT License)
+ * staticwriter.js - buffer writer for bcoin
  * Copyright (c) 2014-2016, Christopher Jeffrey (MIT License).
  * https://github.com/bcoin-org/bcoin
  */
@@ -43,7 +42,7 @@ function StaticWriter(size) {
 StaticWriter.prototype.render = function render(keep) {
   var data = this.data;
 
-  assert.equal(this.written, data.length);
+  assert(this.written === data.length);
 
   if (!keep)
     this.destroy();