diff --git a/bench/ddr3_mr_gen.py b/bench/ddr3_mr_gen.py
new file mode 100755
index 0000000..8cb31f4
--- /dev/null
+++ b/bench/ddr3_mr_gen.py
@@ -0,0 +1,149 @@
+#!/usr/bin/env python3
+
+#
+# This file is part of LiteDRAM.
+#
+# Copyright (c) 2020 Florent Kermarrec <florent@enjoy-digital.fr>
+# SPDX-License-Identifier: BSD-2-Clause
+
+import argparse
+
+parser = argparse.ArgumentParser(description="DDR3 Mode Register settings generator for LiteDRAM.")
+parser.add_argument("--list",        action="store_true", help="List supported DDR3 settings.")
+parser.add_argument("--cl",          default="5",         help="CAS Latency.")
+parser.add_argument("--cwl",         default="5",         help="CAS Write Latency.")
+parser.add_argument("--rtt_nom",     default="60ohm",     help="RTT_NOM value.")
+parser.add_argument("--rtt_wr",      default="60ohm",     help="RTT_WR value.")
+parser.add_argument("--ron",         default="34ohm",     help="RON value.")
+args = parser.parse_args()
+
+# DDR3 Timing settings -----------------------------------------------------------------------------
+cl_to_mr0 = {
+     5: 0b0010,
+     6: 0b0100,
+     7: 0b0110,
+     8: 0b1000,
+     9: 0b1010,
+    10: 0b1100,
+    11: 0b1110,
+    12: 0b0001,
+    13: 0b0011,
+    14: 0b0101
+}
+
+cwl_to_mr2 = {
+   5: 0b000,
+   6: 0b001,
+   7: 0b010,
+   8: 0b011,
+   9: 0b100,
+  10: 0b101,
+}
+
+if args.list:
+  print("Supported DDR3 Timing settings:")
+  print("cl:")
+  for v in cl_to_mr0.keys():
+    print(f" - {v}")
+  print("cwl:")
+  for v in cwl_to_mr2.keys():
+    print(f" - {v}")
+
+# DDR3 Electrical settings -------------------------------------------------------------------------
+z_to_rtt_nom = {
+    "disabled" : 0b000,
+    "60ohm"    : 0b001,
+    "120ohm"   : 0b010,
+    "40ohm"    : 0b011,
+    "20ohm"    : 0b100,
+    "30ohm"    : 0b101
+}
+
+z_to_rtt_wr = {
+    "disabled" : 0b00,
+    "60ohm"    : 0b01,
+    "120ohm"   : 0b10,
+}
+
+z_to_ron = {
+    "40ohm" : 0b0,
+    "34ohm" : 0b1,
+}
+
+if args.list:
+  print("Supported DDR3 Electrical settings:")
+  print("rtt_nom:")
+  for v in z_to_rtt_nom.keys():
+    print(f" - {v}")
+  print("rtt_wr:")
+  for v in z_to_rtt_wr.keys():
+    print(f" - {v}")
+  print("ron:")
+  for v in z_to_ron.keys():
+    print(f" - {v}")
+
+# DDR4 Mode Register formating ---------------------------------------------------------------------
+
+if args.list:
+  exit()
+
+def format_mr0(bl, cl, wr, dll_reset):
+    bl_to_mr0 = {
+        4: 0b10,
+        8: 0b00
+    }
+    wr_to_mr0 = {
+        16: 0b000,
+         5: 0b001,
+         6: 0b010,
+         7: 0b011,
+         8: 0b100,
+        10: 0b101,
+        12: 0b110,
+        14: 0b111
+    }
+    mr0 = bl_to_mr0[bl]
+    mr0 |= (cl_to_mr0[cl] & 1) << 2
+    mr0 |= ((cl_to_mr0[cl] >> 1) & 0b111) << 4
+    mr0 |= dll_reset << 8
+    mr0 |= wr_to_mr0[wr] << 9
+    return mr0
+
+def format_mr1(ron, rtt_nom, tdqs=1):
+    mr1 = ((ron >> 0) & 1) << 1
+    mr1 |= ((ron >> 1) & 1) << 5
+    mr1 |= ((rtt_nom >> 0) & 1) << 2
+    mr1 |= ((rtt_nom >> 1) & 1) << 6
+    mr1 |= ((rtt_nom >> 2) & 1) << 9
+    mr1 |= (tdqs & 1) << 11
+    return mr1
+
+def format_mr2(cwl, rtt_wr):
+    mr2 = (cwl-5) << 3
+    mr2 |= rtt_wr << 9
+    return mr2
+
+print("DDR3 Timing Settings:")
+print(f"cl:  {args.cl}")
+print(f"cwl: {args.cwl}")
+
+print("DDR3 Electrical Settings:")
+print(f"rtt_nom: {args.rtt_nom}")
+print(f"rtt_wr:  {args.rtt_wr}")
+print(f"ron:     {args.ron}")
+
+print("Commands to be used with LiteX BIOS:")
+print("sdram_mr_write 0 {:d}".format(format_mr0(
+  bl         = 8,
+  cl         = int(args.cl, 0),
+  wr         = 10,
+  dll_reset  = 0))
+)
+print("sdram_mr_write 1 {:d}".format(format_mr1(
+  ron        = z_to_ron[args.ron],
+  rtt_nom    = z_to_rtt_nom[args.rtt_nom]))
+)
+print("sdram_mr_write 2 {:d}".format(format_mr2(
+  cwl    = int(args.cwl, 0),
+  rtt_wr = z_to_rtt_wr[args.rtt_wr]))
+)