diff --git a/les/peer.go b/les/peer.go
index 4b69c70350..26c38501ce 100644
--- a/les/peer.go
+++ b/les/peer.go
@@ -49,6 +49,11 @@ const (
 	allowedUpdateRate  = time.Millisecond * 10 // time constant for recharging one byte of allowance
 )
 
+// if the total encoded size of a sent transaction batch is over txSizeCostLimit
+// per transaction then the request cost is calculated as proportional to the
+// encoded size instead of the transaction count
+const txSizeCostLimit = 0x10000
+
 const (
 	announceTypeNone = iota
 	announceTypeSimple
@@ -200,6 +205,32 @@ func (p *peer) GetRequestCost(msgcode uint64, amount int) uint64 {
 	return cost
 }
 
+func (p *peer) GetTxRelayCost(amount, size int) uint64 {
+	p.lock.RLock()
+	defer p.lock.RUnlock()
+
+	var msgcode uint64
+	switch p.version {
+	case lpv1:
+		msgcode = SendTxMsg
+	case lpv2:
+		msgcode = SendTxV2Msg
+	default:
+		panic(nil)
+	}
+
+	cost := p.fcCosts[msgcode].baseCost + p.fcCosts[msgcode].reqCost*uint64(amount)
+	sizeCost := p.fcCosts[msgcode].baseCost + p.fcCosts[msgcode].reqCost*uint64(size)/txSizeCostLimit
+	if sizeCost > cost {
+		cost = sizeCost
+	}
+
+	if cost > p.fcServerParams.BufLimit {
+		cost = p.fcServerParams.BufLimit
+	}
+	return cost
+}
+
 // HasBlock checks if the peer has a given block
 func (p *peer) HasBlock(hash common.Hash, number uint64, hasState bool) bool {
 	p.lock.RLock()
@@ -338,8 +369,8 @@ func (p *peer) RequestTxStatus(reqID, cost uint64, txHashes []common.Hash) error
 }
 
 // SendTxStatus sends a batch of transactions to be added to the remote transaction pool.
-func (p *peer) SendTxs(reqID, cost uint64, txs types.Transactions) error {
-	p.Log().Debug("Fetching batch of transactions", "count", len(txs))
+func (p *peer) SendTxs(reqID, cost uint64, txs rlp.RawValue) error {
+	p.Log().Debug("Sending batch of transactions", "size", len(txs))
 	switch p.version {
 	case lpv1:
 		return p2p.Send(p.rw, SendTxMsg, txs) // old message format does not include reqID
diff --git a/les/txrelay.go b/les/txrelay.go
index 7a02cc837e..5decd6e93a 100644
--- a/les/txrelay.go
+++ b/les/txrelay.go
@@ -21,6 +21,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/rlp"
 )
 
 type ltrInfo struct {
@@ -113,21 +114,22 @@ func (self *LesTxRelay) send(txs types.Transactions, count int) {
 	for p, list := range sendTo {
 		pp := p
 		ll := list
+		enc, _ := rlp.EncodeToBytes(ll)
 
 		reqID := genReqID()
 		rq := &distReq{
 			getCost: func(dp distPeer) uint64 {
 				peer := dp.(*peer)
-				return peer.GetRequestCost(SendTxMsg, len(ll))
+				return peer.GetTxRelayCost(len(ll), len(enc))
 			},
 			canSend: func(dp distPeer) bool {
 				return dp.(*peer) == pp
 			},
 			request: func(dp distPeer) func() {
 				peer := dp.(*peer)
-				cost := peer.GetRequestCost(SendTxMsg, len(ll))
+				cost := peer.GetTxRelayCost(len(ll), len(enc))
 				peer.fcServer.QueueRequest(reqID, cost)
-				return func() { peer.SendTxs(reqID, cost, ll) }
+				return func() { peer.SendTxs(reqID, cost, enc) }
 			},
 		}
 		self.reqDist.queue(rq)