EstimateFee

EstimateFee asks the chain backend to estimate the fee rate and total fees for a transaction that pays to multiple specified outputs.

When using REST, the AddrToAmount map type can be set by appending &AddrToAmount[<address>]=<amount_to_send> to the URL. Unfortunately this map type doesn't appear in the REST API documentation because of a bug in the grpc-gateway library.

Source: lightning.proto

gRPC

rpc EstimateFee (EstimateFeeRequest) returns (EstimateFeeResponse);

REST

HTTP Method	Path
GET	/v1/transactions/fee

Code Samples

gRPC

Javascript

const fs = require('fs');
const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');

const GRPC_HOST = 'localhost:10009'
const MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
const TLS_PATH = 'LND_DIR/tls.cert'

const loaderOptions = {
  keepCase: true,
  longs: String,
  enums: String,
  defaults: true,
  oneofs: true,
};
const packageDefinition = protoLoader.loadSync('lightning.proto', loaderOptions);
const lnrpc = grpc.loadPackageDefinition(packageDefinition).lnrpc;
process.env.GRPC_SSL_CIPHER_SUITES = 'HIGH+ECDSA';
const tlsCert = fs.readFileSync(TLS_PATH);
const sslCreds = grpc.credentials.createSsl(tlsCert);
const macaroon = fs.readFileSync(MACAROON_PATH).toString('hex');
const macaroonCreds = grpc.credentials.createFromMetadataGenerator(function(args, callback) {
  let metadata = new grpc.Metadata();
  metadata.add('macaroon', macaroon);
  callback(null, metadata);
});
let creds = grpc.credentials.combineChannelCredentials(sslCreds, macaroonCreds);
let client = new lnrpc.Lightning(GRPC_HOST, creds);
let request = {
  AddrToAmount: <AddrToAmountEntry>,
  target_conf: <int32>,
  min_confs: <int32>,
  spend_unconfirmed: <bool>,
  coin_selection_strategy: <CoinSelectionStrategy>,
};
client.estimateFee(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "fee_sat": <int64>,
//    "feerate_sat_per_byte": <int64>,
//    "sat_per_vbyte": <uint64>,
//  }

Python

import codecs, grpc, os
# Generate the following 2 modules by compiling the lightning.proto with the grpcio-tools.
# See https://github.com/lightningnetwork/lnd/blob/master/docs/grpc/python.md for instructions.
import lightning_pb2 as lnrpc, lightning_pb2_grpc as lightningstub

GRPC_HOST = 'localhost:10009'
MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
TLS_PATH = 'LND_DIR/tls.cert'

# create macaroon credentials
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
def metadata_callback(context, callback):
  callback([('macaroon', macaroon)], None)
auth_creds = grpc.metadata_call_credentials(metadata_callback)
# create SSL credentials
os.environ['GRPC_SSL_CIPHER_SUITES'] = 'HIGH+ECDSA'
cert = open(TLS_PATH, 'rb').read()
ssl_creds = grpc.ssl_channel_credentials(cert)
# combine macaroon and SSL credentials
combined_creds = grpc.composite_channel_credentials(ssl_creds, auth_creds)
# make the request
channel = grpc.secure_channel(GRPC_HOST, combined_creds)
stub = lightningstub.LightningStub(channel)
request = lnrpc.EstimateFeeRequest(
  AddrToAmount=<AddrToAmountEntry>,
  target_conf=<int32>,
  min_confs=<int32>,
  spend_unconfirmed=<bool>,
  coin_selection_strategy=<CoinSelectionStrategy>,
)
response = stub.EstimateFee(request)
print(response)
# {
#    "fee_sat": <int64>,
#    "feerate_sat_per_byte": <int64>,
#    "sat_per_vbyte": <uint64>,
# }

REST

Javascript

const fs = require('fs');
const request = require('request');

const REST_HOST = 'localhost:8080'
const MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'

let options = {
  url: `https://${REST_HOST}/v1/transactions/fee`,
  // Work-around for self-signed certificates.
  rejectUnauthorized: false,
  json: true,
  headers: {
    'Grpc-Metadata-macaroon': fs.readFileSync(MACAROON_PATH).toString('hex'),
  },
}
request.get(options, function(error, response, body) {
  console.log(body);
});
// Console output:
//  {
//    "fee_sat": <string>, // <int64> 
//    "feerate_sat_per_byte": <string>, // <int64> 
//    "sat_per_vbyte": <string>, // <uint64> 
//  }

Python

import base64, codecs, json, requests

REST_HOST = 'localhost:8080'
MACAROON_PATH = 'LND_DIR/data/chain/bitcoin/regtest/admin.macaroon'
TLS_PATH = 'LND_DIR/tls.cert'

url = f'https://{REST_HOST}/v1/transactions/fee'
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
headers = {'Grpc-Metadata-macaroon': macaroon}
r = requests.get(url, headers=headers, verify=TLS_PATH)
print(r.json())
# {
#    "fee_sat": <int64>,
#    "feerate_sat_per_byte": <int64>,
#    "sat_per_vbyte": <uint64>,
# }

Shell

$ lncli estimatefee --help

NAME:
   lncli estimatefee - Get fee estimates for sending bitcoin on-chain to multiple addresses.

USAGE:
   lncli estimatefee [command options] send-json-string [--conf_target=N]

CATEGORY:
   On-chain

DESCRIPTION:
   
  Get fee estimates for sending a transaction paying the specified amount(s) to the passed address(es).

  The send-json-string' param decodes addresses and the amount to send respectively in the following format:

      '{"ExampleAddr": NumCoinsInSatoshis, "SecondAddr": NumCoins}'
  

OPTIONS:
   --conf_target value              (optional) the number of blocks that the transaction *should* confirm in (default: 0)
   --coin_selection_strategy value  (optional) the strategy to use for selecting coins. Possible values are 'largest', 'random', or 'global-config'. If either 'largest' or 'random' is specified, it will override the globally configured strategy in lnd.conf (default: "global-config")
   

Messages

lnrpc.EstimateFeeRequest

Source: lightning.proto

Field	gRPC Type	REST Type	REST Placement
AddrToAmount The map from addresses to amounts for the transaction.	AddrToAmountEntry[]	object	unknown
target_conf The target number of blocks that this transaction should be confirmed by.	int32	integer	query
min_confs The minimum number of confirmations each one of your outputs used for the transaction must satisfy.	int32	integer	query
spend_unconfirmed Whether unconfirmed outputs should be used as inputs for the transaction.	bool	boolean	query
coin_selection_strategy The strategy to use for selecting coins during fees estimation. Nested REST Parameters coin_selection_strategy: string in query	CoinSelectionStrategy	object	query

lnrpc.EstimateFeeResponse

Source: lightning.proto

Field	gRPC Type	REST Type
fee_sat The total fee in satoshis.	int64	string
feerate_sat_per_bytedeprecated Deprecated, use sat_per_vbyte. The fee rate in satoshi/vbyte.	int64	string
sat_per_vbyte The fee rate in satoshi/vbyte.	uint64	string

Nested Messages

lnrpc.EstimateFeeRequest.AddrToAmountEntry

Field	gRPC Type	REST Type
key	string	unknown
value	int64	unknown

Enums

lnrpc.CoinSelectionStrategy

Name	Number
STRATEGY_USE_GLOBAL_CONFIG Use the coin selection strategy defined in the global configuration (lnd.conf).	0
STRATEGY_LARGEST Select the largest available coins first during coin selection.	1
STRATEGY_RANDOM Randomly select the available coins during coin selection.	2