diff --git a/scripts/app-tls-size.py b/scripts/app-tls-size.py
new file mode 100644
index 000000000..214e4a433
--- /dev/null
+++ b/scripts/app-tls-size.py
@@ -0,0 +1,104 @@
+#!/usr/bin/env python3
+# app-tls-size - Calculate size of Thread-Local Storage
+# Copyright 2022  Simon Arlott
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+# PlatformIO usage:
+#
+# [env:...]
+# extra_scripts = post:app-tls-size.py
+
+import argparse
+import collections
+import re
+import subprocess
+import sys
+
+RE_ELF_SECTION = re.compile(r"^\s*(?P<type>\w+)\s+(?P<offset>\w+)\s+(?P<virtaddr>\w+)\s+(?P<physaddr>\w+)\s+(?P<filesiz>\w+)\s+(?P<memsiz>\w+)\s+(?P<ndx>\w+)\s+")
+Symbol = collections.namedtuple("Symbol", ["value", "size", "line"])
+RE_ELF_SYMBOL = re.compile(r"^(?P<before_value>\s*(?P<num>\w+):\s+)(?P<value>\w+)(?P<after_value>\s+(?P<size>\w+)\s+(?P<type>\w+)\s+(?P<bind>\w+)\s+(?P<visibility>\w+)\s+(?P<ndx>\w+)\s+(?P<name>\w+))")
+
+def print_tls_size(fw_elf):
+	tls_offset = None
+	width = 8
+
+	lines = subprocess.run(["readelf", "-W", "--program-headers", fw_elf],
+			check=True, universal_newlines=True, stdout=subprocess.PIPE
+		).stdout.strip().split("\n")
+
+	for line in lines:
+		match = RE_ELF_SECTION.match(line)
+		if match:
+			if tls_offset is None and match["type"] == "TLS":
+				tls_offset = int(match["virtaddr"], 16)
+
+	header = True
+	lines = subprocess.run(["readelf", "-W", "--syms", "--dyn-syms", fw_elf],
+			check=True, universal_newlines=True, stdout=subprocess.PIPE
+		).stdout.strip().split("\n")
+	syms = set()
+
+	for line in lines:
+		match = RE_ELF_SYMBOL.match(line)
+		if match:
+			header = False
+
+			if match["type"] == "TLS":
+				syms.add(Symbol(int(match["value"], 16), int(match["size"]), line))
+				width = len(match['value'])
+			elif tls_offset is not None and (match["type"] == "NOTYPE" and match["bind"] == "GLOBAL"
+					and match["visibility"] == "DEFAULT"
+					and match["name"] in set(["_thread_local_start", "_thread_local_end"])
+			):
+				value = int(match["value"], 16) - tls_offset
+				line = ("{1}{2:0{0}x}{3}").format(len(match['value']),
+					match["before_value"], value, match["after_value"])
+				syms.add(Symbol(value, int(match["size"]), line))
+
+		elif header:
+			print(line)
+
+	if syms:
+		syms = list(syms)
+		syms.sort()
+		size = (syms[-1].value + syms[-1].size) - syms[0].value
+	else:
+		size = 0
+
+	value = syms[0].value
+	for sym in syms:
+		if sym.value > value:
+			print("\t{1:0{0}x} {2:5d} TLS            UNKNOWN".format(width, value, sym.value - value))
+		print(sym.line)
+		value = sym.value + sym.size
+
+	print()
+	print(f"Total Thread-Local Storage size: {size} bytes")
+
+def after_fw_elf(source, target, env):
+	fw_elf = str(target[0])
+	print_tls_size(fw_elf)
+
+if __name__ == "__main__":
+	parser = argparse.ArgumentParser(description="Calculate size of Thread-Local Storage")
+	parser.add_argument("fw_elf", metavar="ELF", type=str, help="Firmware ELF filename")
+
+	args = parser.parse_args()
+	print_tls_size(**vars(args))
+elif __name__ == "SCons.Script":
+	Import("env")
+
+	env.AddPostAction("${BUILD_DIR}/${PROGNAME}.elf", after_fw_elf)
+    
\ No newline at end of file