diff --git a/rhp/v2/merkle.go b/rhp/v2/merkle.go
index a676295d..ba026283 100644
--- a/rhp/v2/merkle.go
+++ b/rhp/v2/merkle.go
@@ -435,29 +435,6 @@ func VerifyAppendProof(numLeaves uint64, treeHashes []types.Hash256, sectorRoot,
 	return acc.root() == newRoot
 }
 
-// DiffProofSize returns the size of a Merkle diff proof for the specified
-// actions within a tree containing numLeaves leaves.
-func DiffProofSize(actions []RPCWriteAction, numLeaves uint64) (numHashes int) {
-	indices := sectorsChanged(actions, numLeaves)
-	numHashes += len(indices)
-
-	buildRange := func(i, j uint64) {
-		for i < j {
-			subtreeSize := nextSubtreeSize(i, j)
-			numHashes++
-			i += subtreeSize
-		}
-	}
-
-	var start uint64
-	for _, end := range indices {
-		buildRange(start, end)
-		start = end + 1
-	}
-	buildRange(start, numLeaves)
-	return
-}
-
 // BuildDiffProof constructs a diff proof for the specified actions.
 // ActionUpdate is not supported.
 func BuildDiffProof(actions []RPCWriteAction, sectorRoots []types.Hash256) (treeHashes, leafHashes []types.Hash256) {
diff --git a/rhp/v2/rhp.go b/rhp/v2/rhp.go
index 5cbd9a4f..92df35b3 100644
--- a/rhp/v2/rhp.go
+++ b/rhp/v2/rhp.go
@@ -281,10 +281,12 @@ type (
 )
 
 // RPCSectorRootsCost returns the price of a SectorRoots RPC.
-func RPCSectorRootsCost(settings HostSettings, n uint64) types.Currency {
+func RPCSectorRootsCost(settings HostSettings, rootOffset, numRoots uint64) types.Currency {
+	proofSize := RangeProofSize(LeavesPerSector, rootOffset, rootOffset+numRoots)
 	return settings.BaseRPCPrice.
-		Add(settings.DownloadBandwidthPrice.Mul64(n * 32)).  // roots
-		Add(settings.DownloadBandwidthPrice.Mul64(128 * 32)) // proof
+		Add(settings.DownloadBandwidthPrice.Mul64(64)).            // signature
+		Add(settings.DownloadBandwidthPrice.Mul64(numRoots * 32)). // roots
+		Add(settings.DownloadBandwidthPrice.Mul64(proofSize * 32)) // proof
 }
 
 // RPCReadCost returns the price of a Read RPC.
@@ -304,11 +306,12 @@ func RPCReadCost(settings HostSettings, sections []RPCReadRequestSection) types.
 
 // RPCAppendCost returns the price and collateral of a Write RPC with a single
 // append operation.
-func RPCAppendCost(settings HostSettings, storageDuration uint64) (price, collateral types.Currency) {
+func RPCAppendCost(settings HostSettings, storageDuration, numLeaves uint64) (price, collateral types.Currency) {
+	proofSize := uint64(bits.Len64(numLeaves)) + 1 // hashes + new root
 	price = settings.BaseRPCPrice.
 		Add(settings.StoragePrice.Mul64(SectorSize).Mul64(storageDuration)).
 		Add(settings.UploadBandwidthPrice.Mul64(SectorSize)).
-		Add(settings.DownloadBandwidthPrice.Mul64(128 * 32)) // proof
+		Add(settings.DownloadBandwidthPrice.Mul64(proofSize * 32)) // proof
 	collateral = settings.Collateral.Mul64(SectorSize).Mul64(storageDuration)
 	// add some leeway to reduce chance of host rejecting
 	price = price.Mul64(125).Div64(100)
@@ -317,8 +320,8 @@ func RPCAppendCost(settings HostSettings, storageDuration uint64) (price, collat
 }
 
 // RPCDeleteCost returns the price of a Write RPC that deletes n sectors.
-func RPCDeleteCost(settings HostSettings, n int) types.Currency {
-	price := settings.BaseRPCPrice.
-		Add(settings.DownloadBandwidthPrice.Mul64(128 * 32)) // proof
-	return price.Mul64(105).Div64(100)
+func RPCDeleteCost(settings HostSettings, numSectors, numLeaves uint64) types.Currency {
+	proofSize := 2*uint64(bits.Len64(numLeaves))*numSectors + 1 // hashes + new root
+	return settings.BaseRPCPrice.
+		Add(settings.DownloadBandwidthPrice.Mul64(proofSize * 32)) // proof
 }
diff --git a/v2/net/rhp/merkle.go b/v2/net/rhp/merkle.go
index 5067ac5e..3547acb7 100644
--- a/v2/net/rhp/merkle.go
+++ b/v2/net/rhp/merkle.go
@@ -6,7 +6,6 @@ import (
 	"io"
 	"math"
 	"math/bits"
-	"sort"
 	"unsafe"
 
 	"go.sia.tech/core/v2/internal/blake2b"
@@ -245,61 +244,8 @@ func RangeProofSize(n, start, end uint64) uint64 {
 
 // DiffProofSize returns the size of a Merkle diff proof for the specified
 // actions within a tree containing n leaves.
-func DiffProofSize(n uint64, actions []RPCWriteAction) (numHashes int) {
-	indices := sectorsChanged(actions, uint64(n))
-	numHashes += len(indices)
-
-	buildRange := func(i, j uint64) {
-		for i < j {
-			subtreeSize := nextSubtreeSize(i, j)
-			numHashes++
-			i += subtreeSize
-		}
-	}
-
-	var start uint64
-	for _, end := range indices {
-		buildRange(start, end)
-		start = end + 1
-	}
-	buildRange(start, n)
-	return
-}
-
-func sectorsChanged(actions []RPCWriteAction, numSectors uint64) []uint64 {
-	newNumSectors := numSectors
-	sectorsChanged := make(map[uint64]struct{})
-	for _, action := range actions {
-		switch action.Type {
-		case RPCWriteActionAppend:
-			sectorsChanged[newNumSectors] = struct{}{}
-			newNumSectors++
-
-		case RPCWriteActionTrim:
-			for i := uint64(0); i < action.A; i++ {
-				newNumSectors--
-				sectorsChanged[newNumSectors] = struct{}{}
-			}
-
-		case RPCWriteActionSwap:
-			sectorsChanged[action.A] = struct{}{}
-			sectorsChanged[action.B] = struct{}{}
-
-		default:
-			panic("unknown or unsupported action type: " + action.Type.String())
-		}
-	}
-
-	var sectorIndices []uint64
-	for index := range sectorsChanged {
-		if index < numSectors {
-			sectorIndices = append(sectorIndices, index)
-		}
-	}
-	sort.Slice(sectorIndices, func(i, j int) bool {
-		return sectorIndices[i] < sectorIndices[j]
-	})
-	return sectorIndices
+func DiffProofSize(n int, actions []RPCWriteAction) int {
+	return 128 // TODO
 }
 
 // nextSubtreeSize returns the size of the subtree adjacent to start that does
diff --git a/v2/net/rhp/rpc.go b/v2/net/rhp/rpc.go
index c8e7745a..38fe376c 100644
--- a/v2/net/rhp/rpc.go
+++ b/v2/net/rhp/rpc.go
@@ -231,7 +231,7 @@ func RPCWriteRenterCost(settings HostSettings, fc types.FileContract, actions []
 		sectorStoragePrice := settings.StoragePrice.Mul64(SectorSize).Mul64(storageDuration)
 		storageCost = sectorStoragePrice.Mul64(sectorsAdded - sectorsRemoved)
 	}
-	proofSize := DiffProofSize(fc.Filesize/SectorSize, actions)
+	proofSize := DiffProofSize(int(fc.Filesize/SectorSize), actions)
 	downloadBandwidth := uint64(proofSize) * 32
 	return settings.InstrWriteBaseCost.
 		Add(settings.UploadBandwidthPrice.Mul64(sectorsAdded * SectorSize)).