diff --git a/pkg/core/block_test.go b/pkg/core/block_test.go
index ffa159e40..546d1de47 100644
--- a/pkg/core/block_test.go
+++ b/pkg/core/block_test.go
@@ -225,7 +225,7 @@ func TestBlockSizeCalculation(t *testing.T) {
 		txID := tx.Hash()
 		assert.Equal(t, expected[i].ID, txID.ReverseString())
 
-		assert.Equal(t, expected[i].Size, tx.Size())
+		assert.Equal(t, expected[i].Size, io.GetVarSize(tx))
 		assert.Equal(t, expected[i].Type, tx.Type.String())
 		assert.Equal(t, expected[i].Version, int(tx.Version))
 		assert.Equal(t, expected[i].InputsLen, len(tx.Inputs))
diff --git a/pkg/core/blockchain.go b/pkg/core/blockchain.go
index a31b0b037..08e5b298a 100644
--- a/pkg/core/blockchain.go
+++ b/pkg/core/blockchain.go
@@ -628,7 +628,7 @@ func (bc *Blockchain) References(t *transaction.Transaction) map[util.Uint256]*t
 
 // FeePerByte returns network fee divided by the size of the transaction
 func (bc *Blockchain) FeePerByte(t *transaction.Transaction) util.Fixed8 {
-	return bc.NetworkFee(t).Div(int64(t.Size()))
+	return bc.NetworkFee(t).Div(int64(io.GetVarSize(t)))
 }
 
 // NetworkFee returns network fee
@@ -669,8 +669,8 @@ func (bc *Blockchain) GetMemPool() MemPool {
 // Verify verifies whether a transaction is bonafide or not.
 // Golang implementation of Verify method in C# (https://github.com/neo-project/neo/blob/master/neo/Network/P2P/Payloads/Transaction.cs#L270).
 func (bc *Blockchain) Verify(t *transaction.Transaction) error {
-	if t.Size() > transaction.MaxTransactionSize {
-		return errors.Errorf("invalid transaction size = %d. It shoud be less then MaxTransactionSize = %d", t.Size(), transaction.MaxTransactionSize)
+	if io.GetVarSize(t) > transaction.MaxTransactionSize {
+		return errors.Errorf("invalid transaction size = %d. It shoud be less then MaxTransactionSize = %d", io.GetVarSize(t), transaction.MaxTransactionSize)
 	}
 	if ok := bc.verifyInputs(t); !ok {
 		return errors.New("invalid transaction's inputs")
diff --git a/pkg/core/blockchain_test.go b/pkg/core/blockchain_test.go
index a2fcc188e..8f35861c2 100644
--- a/pkg/core/blockchain_test.go
+++ b/pkg/core/blockchain_test.go
@@ -141,7 +141,7 @@ func TestGetTransaction(t *testing.T) {
 	}
 	assert.Equal(t, block.Index, height)
 	assert.Equal(t, block.Transactions[0], tx)
-	assert.Equal(t, 10, tx.Size())
+	assert.Equal(t, 10, io.GetVarSize(tx))
 	assert.Equal(t, 1, io.GetVarSize(tx.Attributes))
 	assert.Equal(t, 1, io.GetVarSize(tx.Inputs))
 	assert.Equal(t, 1, io.GetVarSize(tx.Outputs))
diff --git a/pkg/core/transaction/attribute.go b/pkg/core/transaction/attribute.go
index 3c60d3d5f..425dd72e6 100644
--- a/pkg/core/transaction/attribute.go
+++ b/pkg/core/transaction/attribute.go
@@ -74,23 +74,6 @@ func (attr *Attribute) EncodeBinary(bw *io.BinWriter) error {
 	return bw.Err
 }
 
-// Size returns the size in number bytes of the Attribute
-func (attr *Attribute) Size() int {
-	sz := 1 // usage
-	switch attr.Usage {
-	case ContractHash, ECDH02, ECDH03, Vote,
-		Hash1, Hash2, Hash3, Hash4, Hash5, Hash6, Hash7, Hash8, Hash9, Hash10, Hash11, Hash12, Hash13, Hash14, Hash15:
-		sz += 32 // uint8 + 32 = size(attrUsage) + 32
-	case Script:
-		sz += 20 // uint8 + 20 = size(attrUsage) + 20
-	case DescriptionURL:
-		sz += 1 + len(attr.Data)
-	default:
-		sz += io.GetVarSize(attr.Data)
-	}
-	return sz
-}
-
 // MarshalJSON implements the json Marschaller interface
 func (attr *Attribute) MarshalJSON() ([]byte, error) {
 	return json.Marshal(map[string]string{
diff --git a/pkg/core/transaction/claim.go b/pkg/core/transaction/claim.go
index 6c1a69eda..61d44614c 100644
--- a/pkg/core/transaction/claim.go
+++ b/pkg/core/transaction/claim.go
@@ -38,12 +38,3 @@ func (tx *ClaimTX) EncodeBinary(bw *io.BinWriter) error {
 	}
 	return nil
 }
-
-// Size returns serialized binary size for this transaction.
-func (tx *ClaimTX) Size() int {
-	sz := io.GetVarSize(uint64(len(tx.Claims)))
-	for _, claim := range tx.Claims {
-		sz += claim.Size()
-	}
-	return sz
-}
diff --git a/pkg/core/transaction/contract.go b/pkg/core/transaction/contract.go
index c7d91fa12..4c445da21 100644
--- a/pkg/core/transaction/contract.go
+++ b/pkg/core/transaction/contract.go
@@ -24,8 +24,3 @@ func (tx *ContractTX) DecodeBinary(r *io.BinReader) error {
 func (tx *ContractTX) EncodeBinary(w *io.BinWriter) error {
 	return nil
 }
-
-// Size returns serialized binary size for this transaction.
-func (tx *ContractTX) Size() int {
-	return 0
-}
diff --git a/pkg/core/transaction/enrollment.go b/pkg/core/transaction/enrollment.go
index 9ef1b4f68..d01b3eedb 100644
--- a/pkg/core/transaction/enrollment.go
+++ b/pkg/core/transaction/enrollment.go
@@ -25,8 +25,3 @@ func (tx *EnrollmentTX) DecodeBinary(r *io.BinReader) error {
 func (tx *EnrollmentTX) EncodeBinary(w *io.BinWriter) error {
 	return tx.PublicKey.EncodeBinary(w)
 }
-
-// Size returns serialized binary size for this transaction.
-func (tx *EnrollmentTX) Size() int {
-	return len(tx.PublicKey.Bytes())
-}
diff --git a/pkg/core/transaction/input.go b/pkg/core/transaction/input.go
index cce3db6c3..a5a13411d 100644
--- a/pkg/core/transaction/input.go
+++ b/pkg/core/transaction/input.go
@@ -27,8 +27,3 @@ func (in *Input) EncodeBinary(bw *io.BinWriter) error {
 	bw.WriteLE(in.PrevIndex)
 	return bw.Err
 }
-
-// Size returns the size in bytes of the Input
-func (in Input) Size() int {
-	return in.PrevHash.Size() + 2 // 2 = sizeOf uint16
-}
diff --git a/pkg/core/transaction/invocation.go b/pkg/core/transaction/invocation.go
index bfdf3df66..43a2409ed 100644
--- a/pkg/core/transaction/invocation.go
+++ b/pkg/core/transaction/invocation.go
@@ -50,12 +50,3 @@ func (tx *InvocationTX) EncodeBinary(bw *io.BinWriter) error {
 	}
 	return bw.Err
 }
-
-// Size returns serialized binary size for this transaction.
-func (tx *InvocationTX) Size() int {
-	sz := io.GetVarSize(tx.Script)
-	if tx.Version >= 1 {
-		sz += tx.Gas.Size()
-	}
-	return sz
-}
diff --git a/pkg/core/transaction/issue.go b/pkg/core/transaction/issue.go
index 7555d267b..9f412e97a 100644
--- a/pkg/core/transaction/issue.go
+++ b/pkg/core/transaction/issue.go
@@ -17,8 +17,3 @@ func (tx *IssueTX) DecodeBinary(r *io.BinReader) error {
 func (tx *IssueTX) EncodeBinary(w *io.BinWriter) error {
 	return nil
 }
-
-// Size returns serialized binary size for this transaction.
-func (tx *IssueTX) Size() int {
-	return 0
-}
diff --git a/pkg/core/transaction/miner.go b/pkg/core/transaction/miner.go
index b64fbee9b..923253926 100644
--- a/pkg/core/transaction/miner.go
+++ b/pkg/core/transaction/miner.go
@@ -21,8 +21,3 @@ func (tx *MinerTX) EncodeBinary(w *io.BinWriter) error {
 	w.WriteLE(tx.Nonce)
 	return w.Err
 }
-
-// Size returns serialized binary size for this transaction.
-func (tx *MinerTX) Size() int {
-	return 4 // Nonce
-}
diff --git a/pkg/core/transaction/output.go b/pkg/core/transaction/output.go
index 887bcb18f..a6aacbdca 100644
--- a/pkg/core/transaction/output.go
+++ b/pkg/core/transaction/output.go
@@ -49,11 +49,6 @@ func (out *Output) EncodeBinary(bw *io.BinWriter) error {
 	return bw.Err
 }
 
-// Size returns the size in bytes of the Output
-func (out *Output) Size() int {
-	return out.AssetID.Size() + out.Amount.Size() + out.ScriptHash.Size()
-}
-
 // MarshalJSON implements the Marshaler interface
 func (out *Output) MarshalJSON() ([]byte, error) {
 	return json.Marshal(map[string]interface{}{
diff --git a/pkg/core/transaction/publish.go b/pkg/core/transaction/publish.go
index fbf3d11d6..6a07fdfce 100644
--- a/pkg/core/transaction/publish.go
+++ b/pkg/core/transaction/publish.go
@@ -69,17 +69,3 @@ func (tx *PublishTX) EncodeBinary(bw *io.BinWriter) error {
 	bw.WriteString(tx.Description)
 	return bw.Err
 }
-
-// Size returns serialized binary size for this transaction.
-func (tx *PublishTX) Size() int {
-	sz := io.GetVarSize(tx.Script) + io.GetVarSize(uint64(len(tx.ParamList)))
-	sz += 1 * len(tx.ParamList)
-	sz++
-	if tx.Version >= 1 {
-		sz++
-	}
-	sz += io.GetVarSize(tx.Name) + io.GetVarSize(tx.CodeVersion)
-	sz += io.GetVarSize(tx.Author) + io.GetVarSize(tx.Email)
-	sz += io.GetVarSize(tx.Description)
-	return sz
-}
diff --git a/pkg/core/transaction/register.go b/pkg/core/transaction/register.go
index 1d45aa23e..c3c227165 100644
--- a/pkg/core/transaction/register.go
+++ b/pkg/core/transaction/register.go
@@ -59,8 +59,3 @@ func (tx *RegisterTX) EncodeBinary(bw *io.BinWriter) error {
 	bw.WriteLE(tx.Admin)
 	return bw.Err
 }
-
-// Size returns serialized binary size for this transaction.
-func (tx *RegisterTX) Size() int {
-	return 1 + io.GetVarSize(tx.Name) + tx.Amount.Size() + 1 + len(tx.Owner.Bytes()) + tx.Admin.Size()
-}
diff --git a/pkg/core/transaction/state.go b/pkg/core/transaction/state.go
index be52ef734..8723b972d 100644
--- a/pkg/core/transaction/state.go
+++ b/pkg/core/transaction/state.go
@@ -34,12 +34,3 @@ func (tx *StateTX) EncodeBinary(w *io.BinWriter) error {
 	}
 	return w.Err
 }
-
-// Size returns serialized binary size for this transaction.
-func (tx *StateTX) Size() int {
-	sz := io.GetVarSize(uint64(len(tx.Descriptors)))
-	for _, desc := range tx.Descriptors {
-		sz += desc.Size()
-	}
-	return sz
-}
diff --git a/pkg/core/transaction/state_descriptor.go b/pkg/core/transaction/state_descriptor.go
index 4c794fceb..40dbbcf14 100644
--- a/pkg/core/transaction/state_descriptor.go
+++ b/pkg/core/transaction/state_descriptor.go
@@ -40,8 +40,3 @@ func (s *StateDescriptor) EncodeBinary(w *io.BinWriter) error {
 	w.WriteString(s.Field)
 	return w.Err
 }
-
-// Size returns serialized binary size for state descriptor.
-func (s *StateDescriptor) Size() int {
-	return 1 + io.GetVarSize(s.Key) + io.GetVarSize(s.Value) + io.GetVarSize(s.Field)
-}
diff --git a/pkg/core/transaction/transaction.go b/pkg/core/transaction/transaction.go
index cd9e3c352..628677f21 100644
--- a/pkg/core/transaction/transaction.go
+++ b/pkg/core/transaction/transaction.go
@@ -263,16 +263,6 @@ func (t Transaction) GroupOutputByAssetID() map[util.Uint256][]*Output {
 	return m
 }
 
-// Size returns the size of the transaction in term of bytes
-func (t *Transaction) Size() int {
-	attrSize := io.GetVarSize(t.Attributes)
-	inputSize := io.GetVarSize(t.Inputs)
-	outputSize := io.GetVarSize(t.Outputs)
-	witnesSize := io.GetVarSize(t.Scripts)
-	// uint8 + uint8 + attrSize + inputSize + outputSize + witnesSize
-	return 2 + attrSize + inputSize + outputSize + witnesSize + t.Data.Size()
-}
-
 // Bytes convert the transaction to []byte
 func (t *Transaction) Bytes() []byte {
 	buf := io.NewBufBinWriter()
diff --git a/pkg/core/transaction/txer.go b/pkg/core/transaction/txer.go
index c26c6364c..62558143b 100644
--- a/pkg/core/transaction/txer.go
+++ b/pkg/core/transaction/txer.go
@@ -7,5 +7,4 @@ import "github.com/CityOfZion/neo-go/pkg/io"
 type TXer interface {
 	DecodeBinary(*io.BinReader) error
 	EncodeBinary(*io.BinWriter) error
-	Size() int
 }
diff --git a/pkg/core/transaction/witness.go b/pkg/core/transaction/witness.go
index d4da3836a..9256ecc16 100644
--- a/pkg/core/transaction/witness.go
+++ b/pkg/core/transaction/witness.go
@@ -40,11 +40,6 @@ func (w *Witness) MarshalJSON() ([]byte, error) {
 	return json.Marshal(data)
 }
 
-// Size returns the size in bytes of the Witness.
-func (w *Witness) Size() int {
-	return io.GetVarSize(w.InvocationScript) + io.GetVarSize(w.VerificationScript)
-}
-
 // ScriptHash returns the hash of the VerificationScript.
 func (w Witness) ScriptHash() util.Uint160 {
 	return hash.Hash160(w.VerificationScript)
diff --git a/pkg/io/serializable.go b/pkg/io/serializable.go
index 0f49c61d8..2063d2c6d 100644
--- a/pkg/io/serializable.go
+++ b/pkg/io/serializable.go
@@ -2,7 +2,6 @@ package io
 
 // Serializable defines the binary encoding/decoding interface.
 type Serializable interface {
-	Size() int
 	DecodeBinary(*BinReader) error
 	EncodeBinary(*BinWriter) error
 }
diff --git a/pkg/io/size_test.go b/pkg/io/size_test.go
index 9a5d2de66..85275fe94 100644
--- a/pkg/io/size_test.go
+++ b/pkg/io/size_test.go
@@ -22,10 +22,6 @@ func (ss *smthSerializable) EncodeBinary(bw *BinWriter) error {
 	return nil
 }
 
-func (*smthSerializable) Size() int {
-	return 42
-}
-
 func TestVarSize(t *testing.T) {
 	testCases := []struct {
 		variable interface{}
diff --git a/pkg/network/payload/getblocks.go b/pkg/network/payload/getblocks.go
index f1e3e1fc1..3298c5b5a 100644
--- a/pkg/network/payload/getblocks.go
+++ b/pkg/network/payload/getblocks.go
@@ -38,6 +38,3 @@ func (p *GetBlocks) EncodeBinary(bw *io.BinWriter) error {
 	bw.WriteLE(p.HashStop)
 	return bw.Err
 }
-
-// Size implements the payload interface.
-func (p *GetBlocks) Size() uint32 { return 0 }
diff --git a/pkg/network/payload/version.go b/pkg/network/payload/version.go
index de78b1b3b..2cb79fbe2 100644
--- a/pkg/network/payload/version.go
+++ b/pkg/network/payload/version.go
@@ -79,8 +79,3 @@ func (p *Version) EncodeBinary(br *io.BinWriter) error {
 	br.WriteLE(&p.Relay)
 	return br.Err
 }
-
-// Size implements the payloader interface.
-func (p *Version) Size() uint32 {
-	return uint32(minVersionSize + io.GetVarSize(p.UserAgent))
-}
diff --git a/pkg/network/payload/version_test.go b/pkg/network/payload/version_test.go
index 559fe94ed..5c4b3b73e 100644
--- a/pkg/network/payload/version_test.go
+++ b/pkg/network/payload/version_test.go
@@ -20,7 +20,7 @@ func TestVersionEncodeDecode(t *testing.T) {
 	err := version.EncodeBinary(buf.BinWriter)
 	assert.Nil(t, err)
 	b := buf.Bytes()
-	assert.Equal(t, int(version.Size()), len(b))
+	assert.Equal(t, io.GetVarSize(version), len(b))
 
 	r := io.NewBinReaderFromBuf(b)
 	versionDecoded := &Version{}
diff --git a/pkg/rpc/wrappers/tx_raw_output.go b/pkg/rpc/wrappers/tx_raw_output.go
index d3ebbd33a..7a8a6fcf7 100644
--- a/pkg/rpc/wrappers/tx_raw_output.go
+++ b/pkg/rpc/wrappers/tx_raw_output.go
@@ -3,6 +3,7 @@ package wrappers
 import (
 	"github.com/CityOfZion/neo-go/pkg/core"
 	"github.com/CityOfZion/neo-go/pkg/core/transaction"
+	"github.com/CityOfZion/neo-go/pkg/io"
 	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
@@ -30,7 +31,7 @@ func NewTransactionOutputRaw(tx *transaction.Transaction, header *core.Header, c
 	return TransactionOutputRaw{
 		Transaction:   tx,
 		TxHash:        tx.Hash(),
-		Size:          tx.Size(),
+		Size:          io.GetVarSize(tx),
 		SysFee:        chain.SystemFee(tx),
 		NetFee:        chain.NetworkFee(tx),
 		Blockhash:     header.Hash(),
diff --git a/pkg/util/fixed8.go b/pkg/util/fixed8.go
index ec7b96d61..1364a0601 100644
--- a/pkg/util/fixed8.go
+++ b/pkg/util/fixed8.go
@@ -104,11 +104,6 @@ func (f *Fixed8) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
-// Size returns the size in number of bytes of Fixed8.
-func (f *Fixed8) Size() int {
-	return 8
-}
-
 // MarshalJSON implements the json marshaller interface.
 func (f Fixed8) MarshalJSON() ([]byte, error) {
 	return []byte(`"` + f.String() + `"`), nil
diff --git a/pkg/util/uint160.go b/pkg/util/uint160.go
index 996bd9334..8c9202935 100644
--- a/pkg/util/uint160.go
+++ b/pkg/util/uint160.go
@@ -70,11 +70,6 @@ func (u *Uint160) UnmarshalJSON(data []byte) (err error) {
 	return err
 }
 
-// Size returns the length of the bytes representation of Uint160
-func (u Uint160) Size() int {
-	return uint160Size
-}
-
 // MarshalJSON implements the json marshaller interface.
 func (u Uint160) MarshalJSON() ([]byte, error) {
 	return []byte(`"0x` + u.String() + `"`), nil
diff --git a/pkg/util/uint256.go b/pkg/util/uint256.go
index 0dbad3f89..4de10b135 100644
--- a/pkg/util/uint256.go
+++ b/pkg/util/uint256.go
@@ -82,11 +82,6 @@ func (u *Uint256) UnmarshalJSON(data []byte) (err error) {
 	return err
 }
 
-// Size returns the length of the bytes representation of Uint256
-func (u Uint256) Size() int {
-	return uint256Size
-}
-
 // MarshalJSON implements the json marshaller interface.
 func (u Uint256) MarshalJSON() ([]byte, error) {
 	return []byte(`"0x` + u.ReverseString() + `"`), nil