diff --git a/src/4_2_i_txfee-calc.sh b/src/4_2_i_txfee-calc.sh
new file mode 100644
index 0000000..b031ab6
--- /dev/null
+++ b/src/4_2_i_txfee-calc.sh
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+if [ -z $1 ];
+then
+    echo "You must include the raw transaction hex as an argument.";
+    exit;
+fi
+
+usedtxid=($(bitcoin-cli decoderawtransaction $1 | jq -r '.vin | .[] | .txid'))
+usedvout=($(bitcoin-cli decoderawtransaction $1 | jq -r '.vin | .[] | .vout'))
+btcin=$(for ((i=0; i<${#usedtxid[*]}; i++)); do txid=${usedtxid[i]}; vout=${usedvout[i]}; bitcoin-cli listunspent | jq -r '.[] | select (.txid | contains("'${txid}'")) | select(.vout | contains('$vout')) | .amount'; done | awk '{s+=$1} END {print s}')
+btcout=$(bitcoin-cli decoderawtransaction $1 | jq -r '.vout  [] | .value' | awk '{s+=$1} END {print s}')
+echo "$btcin-$btcout"| /usr/bin/bc