Designations Of U.S. Nuclear Weapons

Copyright © 2001-2023 Andreas Parsch

1 Designation System

2 List of Weapons

3 Sources

1 Designation System

All U.S. nuclear weapons (missile warheads, free-fall bombs, artillery shells, etc.) are numbered in a single, consecutive series. The numbers are assigned by the organization controlling the design and manufacture of nuclear weapons. From 1946 to 1974, this was the Atomic Energy Commission (AEC). In 1974, the AEC was abolished and its tasks being taken over by the newly formed Energy Research and Development Administration (ERDA). In 1977, the Department of Energy (DOE) was founded and took over, among many other things, the responsibility for nuclear weapons.

When designating nuclear weapons, a variety of prefixes and suffixes are used with the numbers. However, I don't have any official, first-hand source describing or regulating their use. The following prefixes were used at least once:

The first four designs used roman numerals, but this was soon changed to arabic numerals with the MK-IV/MK-4. A dash is usually written between the prefix and the number. In newer references, however, the dash is frequently omitted. Especially the reference to bombs as Bn instead of B-n is quite common, presumably to avoid confusion with US Air Force bomber designations. The warhead (i.e. the nuclear package) of a free-fall bomb always retained its W designation, using the same number as the bomb itself. E.g. the nuclear components of the MK-28 bomb were known as W-28 (in the strictest sense, the MK nomenclature applied only to the non-nuclear bomb components).

Suffixes are used to designate variants of a weapon. The basic suffix is a "Mod" designator. This is used in the same way as in the US Navy's MARK/MOD Nomenclature System, i.e. the first version is designated "Mod 0", followed by "Mod 1", etc. The Mod suffix is often abbreviated to a dash and a number, e.g. B61-11 or W80-1. Different yield options for a weapon can be indicated by a Yn (n = 1, 2, ...) designator immediately behind the number. Of course, Y and Mod suffixes can be combined, as in W-39Y1 Mod 2. Modifications of bomb and warhead prototypes were often indicated by a -Xn (n = 1, 2, ...) suffix, as in TX-7-X1. If an -Xn design was put into production, the -Xn usually became a Mod number (e.g. TX-7-X1 became MK-7 Mod 1).

2 List of Weapons

The list includes every nuclear weapon which was ever assigned a number in the AEC/DOE series. Warheads are always listed as W-n, but bombs are generally shown with the most "common" prefix. All warheads had XW or TX designations when the number was first assigned. Similarly, most bombs started as TX designs before being designated as MK, B or EC.

For each weapon, the developing laboratory (LANL = Los Alamos National Laboratory, LLNL = Lawrence Livermore National Laboratory), the approximate yield(s) and the delivery platforms (carrier aircraft for bombs, missiles for warheads) are listed. Brackets indicate cancelled bombs, warheads and platform/warhead combinations.

Most rockets and missile designations are linked to the corresponding page in the Directory of U.S. Military Rockets and Missiles, which includes detailed information about the weapon.

Number Laboratory Yield   Platforms Remarks
MK-I LANL 15 kT   B-29 Superfortress "Little Boy" (dropped on Hiroshima) was a MK-I type bomb
[MK-II] LANL     Design similar to "Fat Man"; not developed
MK-III LANL 18 kT - 49 kT   B-29 Superfortress
  B-50A/D Superfortress
"Fat Man" (dropped on Nagasaki) was a MK-III type bomb
MK-IV/MK-4
[W-4]
LANL 1 kT - 31 kT MK-4 Bomb:
  B-29 Superfortress
  B-36 Peacemaker
  B-50A/D Superfortress
  AJ, A-2 Savage
W-4 Warhead:
  [B-62, SM-62 Snark]
  [B-64, SM-64 Navaho]
Derived from MK-III Mod 1; W-4 missile warhead cancelled in favour of W-13
MK-5
W-5
LANL 11 kT - 47 kT MK-5 Bomb:
  B-29 Superfortress
  B-36 Peacemaker
  B-45A Tornado
  B-47A/B/E Stratojet
  B-50A/D Superfortress
  B-66 Destroyer
  AJ, A-2 Savage
  A3D-1/2, A-3A/B Skywarrior
W-5 Warhead:
  B-61, TM-61A/C, MGM-1C Matador
  SSM-N-8a, RGM-6B Regulus
  [B-63, GAM-63 Rascal]
  [SSM-N-2 Triton]
  [SSM-N-6 Rigel]
  [SSM-A-16 Hermes A-3B]
XW-5 for GAM-63 was cancelled in favour of W-27
MK-6 LANL 8 kT - 160 kT   B-29 Superfortress
  B-36 Peacemaker
  B-47A/B/E Stratojet
  B-50A/D Superfortress
  B-66 Destroyer
  AJ, A-2 Savage
  A3D-1, A-3A Skywarrior
Improved MK-4; some retired MK-6 bombs were converted into "Project A" ADM (ADM-A)
MK-7
W-7
LANL MK-7: 8 kT - 61 kT
W-7: 90 T, 2 - 40 kT
MK-7 Bomb:
  B-45A Tornado
  B-57B Intruder
  F-84E/F/G Thunderjet/Thunderstreak
  F-100D/F Super Sabre
  F-101A/C Voodoo
  AD-4B Skyraider
  AJ, A-2 Savage
  A3D-1, A-3A Skywarrior
  A4D-2/5, A-4B/C/E/J/M Skyhawk
  FJ-4B, AF-1E Fury
  F2H-2B Banshee
  F3H-2N, F-3C Demon
  F9F-8B, AF-9J Cougar
W-7 Warhead:
  30.5" Rocket MK 1 MOD 0 BOAR
  SSM-A-17, M2, MGM-5A/B Corporal
  M31/M50, MGR-1A/B/C Honest John
  "Project B" ADM (ADM-B)
  MK 90 Betty ASW Bomb
  [GAM-67 Crossbow]
  [SSM-A-13 Hermes A-2]
  [SAM-A-25, M6, MIM-14 Nike Hercules]
MK-7 was nicknamed "Thor";
XW-7 for GAM-67 and MIM-14 was cancelled in favour of W-31
MK-8
[W-8]
LANL 25 kT - 30 kT MK-8 Bomb:
  B-45A Tornado
  AD-4B Skyraider
  AJ, A-2 Savage
  A3D-1, A-3A Skywarrior
  A4D-2/5, A-4B/C/E/J/M Skyhawk
  F2H-2B Banshee
  F3H-2N, F-3C Demon
W-8 Warhead:
  [SSM-N-8, RGM-6 Regulus]
MK-8 was nicknamed "Elsie" (for "LC": Light Case); replaced by MK-11
W-9 LANL 15 kT   T-124 280 mm Artillery Shell
  T-4 ADM
 
[TX-10]
[W-10]
LANL 12 kT - 15 kT W-10 Warhead:
  [KGW-1 Loon]
TX-10 was to be an airburst derivative of the MK-8
TX-11 (MK-91) LANL 30 kT (?)   AD-4B/7, A-1J Skyraider
  AJ, A-2 Savage
  A3D-1, A-3A Skywarrior
  A4D-2/5, A-4B/C/E/J/M Skyhawk
  F2H-2B Banshee
  F3H-2N, F-3C Demon
Improved MK-8; MK-11 production version was known as MK-91 Mod 0 bomb
MK-12
[W-12]
LANL 12 kT, 14 kT MK-12 Bomb:
  F-86F/H Sabre
  AD-6/7, A-1H/J Skyraider
  AJ, A-2 Savage
  A3D-1, A-3A Skywarrior
  A4D-2/5, A-4B/C/E/J/M Skyhawk
  FJ-4B, AF-1E Fury
  F2H-2B Banshee
  F3H-2N, F-3C Demon
  F9F-8B, AF-9J Cougar
W-12 Warhead:
  [SAM-N-6, IM-70, RIM-8 Talos]
  [30.5" Rocket MK 1 MOD 0 BOAR]
MK-12 was nicknamed "Brok";
W-12 was cancelled in favour of W-7 (BOAR) and W-30 (Talos)
[TX-13]
[W-13]
LANL 32 kT W-13 Warhead:
  [B-62, SM-62 Snark]
  [B-64, SM-64 Navaho]
  [SSM-A-14, M8, PGM-11 Redstone]
W-13 was cancelled in favour of W-15 and later W-39
EC-14 LANL 5 MT - 7 MT   B-36 Peacemaker  
MK-15
[W-15]
LANL 1.7 MT, 3.4 MT MK-15 Bomb:
  B-36 Peacemaker
  B-47B/E Stratojet
  B-52 Stratofortress
  A3D-1, A-3A Skywarrior
W-15 Warhead:
  [B-62, SM-62 Snark]
  [B-64, SM-64 Navaho]
  [SSM-A-14, M8, PGM-11 Redstone]
W-15 was cancelled in favour of W-39
[TX-16] LANL 6 MT - 8 MT    
MK-17 LANL 15 MT - 20 MT   B-36 Peacemaker  
MK-18 LANL 500 kT   B-36 Peacemaker
  B-47A/B/E Stratojet
  A3D-1, A-3A Skywarrior
 
S-19 LANL 15 kT   T-315 280 mm Artillery Shell  
[TX-20] LANL     Proposed high-yield derivative of MK-13
MK-21
[W-21]
LANL 4 MT - 5 MT MK-21 Bomb:
  B-36 Peacemaker
  B-47B/E Stratojet
  B-52 Stratofortress
W-21 Warhead:
  [B-64, SM-64 Navaho]
Later converted to MK-36
[TX-22] LLNL     Design cancelled after preliminary test failure
S-23 LANL 15 kT - 20 kT   16" Shipborne Gun Shell A 280 mm shell warhead incorporated into a bigger shellcase for the 16" guns
MK-24 LANL 15 MT - 20 MT   B-36 Peacemaker Very similar to MK-17
W-25 LANL 1.7 kT   MB-1, AIR-2A Genie
  [M51, MGR-3 Little John]
  ["Project C" ADM (ADM-C)]
 
[TX-26] LANL     Cancelled derivative of MK-21
MK-27
W-27
LLNL 2 MT MK-27 Bomb:
  AJ, A-2 Savage
  A3D-1/2, A-3A/B Skywarrior
  A3J-1, A-5A Vigilante
W-27 Warhead:
  SSM-N-8a, RGM-6B Regulus
  [B-61, TM-61, MGM-1 Matador]
  [B-63, GAM-63 Rascal]
  [SSM-N-2 Triton]
  [SSM-N-9, RGM-15 Regulus II]
 
MK-28
W-28
LANL MK-28: 70 kT (Y1), 350 kT (Y2), 1.1 MT (Y3), 1.45 MT (Y5)
W-28: 11 kT - 1.1 MT
MK-28 Bomb:
  B-47B/E Stratojet
  B-52 Stratofortress
  B-66 Destroyer
  F-100D/F Super Sabre
  F-101A/C Voodoo
  F-104C/G Starfighter
  F-105 Thunderchief
  F/FB-111 Aardvark
  F-4C/D/E Phantom II
  A3D-1/2, A-3A/B Skywarrior
  A4D-2/5, A-4B/C/E/J/M Skyhawk
  A3J-1, A-5A Vigilante
  A2F, A-6 Intruder
  A-7 Corsair II
  FJ-4B, AF-1E Fury
W-28 Warhead:
  TM-76A/B, MGM/CGM-13A/B Mace
  GAM-77/A, AGM-28A/B Hound Dog
Used W-34 "Python" as fission primary
[W-29] LANL     [B-64, SM-64 Navaho]
  [SSM-A-14, M8, PGM-11 Redstone]
Modified W-15; cancelled in favour of W-39
W-30 LANL 0.5 kT, 2 kT   SAM-N-6bW/bW1/c1, RIM-8B/D/E Talos
  XM113 TADM
  [F-99, IM-99, CIM-10 Bomarc]
  [AIM-68 Big Q]
Used as "Boa" fission primary in W-52; W-30/Bomarc cancelled in favour of W-40
W-31 LANL 2 kT, 20 kT, 40 kT (MGR-1)
1 kT - 2 kT, 30 kT - 40 kT (MIM-14)
1 kT - 40 kT (ADM)
  M31/M50, MGR-1A/B/C Honest John (Y3)
  SAM-A-25, M6, MIM-14A/B/C Nike Hercules (Y1, Y2)
  ADM
  [GAM-67 Crossbow]
 
[S-32] LANL     [T-332 240 mm Artillery Shell] Cancelled in favour of W-48
W-33 LANL 5 kT - 40 kT   M422 8" Artillery Shell  
W-34 LANL 11 kT   MK 101 Lulu NDB (Nuclear Depth Bomb)
  MK 105 Hotpoint Bomb
  MK 45 ASTOR Torpedo
Nicknamed "Python"; also used as gas-boosted fission primary in W-28, W-40 and W-49
[W-35] LANL 1.75 MT   [SM-65D/E/F, CGM/HGM-16D/E/F Atlas]
  [SM-68, HGM-25A Titan]
  [SM-75, PGM-17 Thor]
  [SM-78, PGM-19 Jupiter]
Cancelled in favour of W-38 (Atlas E/F, Titan) and W-49 (Atlas D, Thor, Jupiter)
MK-36 LANL 10 MT   B-36 Peacemaker
  B-47B/E Stratojet
  B-52 Stratofortress
 
[W-37] LANL     [SAM-A-25, M6, MIM-14 Nike Hercules] XW-37 was redesignated XW-31Y2
W-38 LLNL 4.5 MT   SM-65E/F, CGM-16E/F Atlas
  SM-68, HGM-25A Titan
Used "Robin" (see W-48) as fission primary
MK-39
W-39
LLNL 3 MT - 4 MT MK-39 Bomb:
  B-36 Peacemaker
  B-47B/E Stratojet
  B-52 Stratofortress
  B-58 Hustler (BA-39 in bomb pod)
  A3D-1, A-3A Skywarrior
W-39 Warhead:
  B-62, SM-62A Snark
  SSM-A-14, M8, PGM-11A Redstone
  [B-64, SM-64 Navaho]
 
W-40 LANL 7 kT - 10 kT (CIM-10)
1.7 kT, 10 kT (MGM-18)
  F-99, IM-99A/B, CIM-10A/B Bomarc
  SSM-A-12, M4, MGM-18A Lacrosse
  [ASM-N-8 Corvus]
Used W-34 "Python" as fission primary
MK-41
[W-41]
LLNL 25 MT MK-41 Bomb:
  B-47B/E Stratojet
  B-52 Stratofortress
 
[W-42] LLNL     [GAR-9, AIM-47 Falcon]
  [AAM-N-9 Sparrow X]
  [AAM-N-10 Eagle]
  [SAM-A-18, M3, MIM-23 Hawk]
Cancelled in favour of W-54
MK-43 LANL 70 kT, 500 kT, 1 MT   B-47B/E Stratojet
  B-52 Stratofortress
  B-57B Intruder
  B-58 Hustler
  F-100D/F Super Sabre
  F-101A/C Voodoo
  F-104C/G Starfighter
  F-105 Thunderchief
  F/FB-111 Aardvark
  F-4C/D/E Phantom II
  A3D-1/2, A-3A/B Skywarrior
  A4D-2/5, A-4B/C/E/J/M Skyhawk
  A3J-1, A-5A Vigilante
  A2F, A-6 Intruder
  A-7 Corsair II
  FJ-4B, AF-1E Fury
Used W-44 "Tsetse" as fission primary
W-44 LANL 300 T, 10 kT   RUR-5A Asroc Nicknamed "Tsetse"; also used as fission primary in MK-43, W-50, MK-57 and W-59
W-45 LLNL 500 T - 15 kT   GAM-83B, AGM-12D Bullpup (Y3, Y4)
  SAM-N-7, RIM-2D Terrier (Y1, Y4)
  M51, MGR-3A Little John (Y1, Y2, Y4)
  MADM (Y1, Y2, Y3, Y4)
Used "Robin" (see W-48) as fission primary
[TX-46]
[W-46]
LANL 10 MT W-46 Warhead:
  [SSM-A-14, M8, PGM-11 Redstone]
Cancelled in favour of MK-53/W-53
W-47 LLNL 600 kT (Y1), 1.2 MT (Y2)   UGM-27A/B Polaris A1/A2 Used "Robin" (see W-48) as fission primary
W-48 LLNL 70 T - 100 T   M454 155 mm Artillery Shell Unboosted derivative of "Robin" fission primary of W-38, W-45 and W-47
W-49 LANL 1.45 MT   SM-65D, PGM-16D Atlas
  SM-75, PGM-17A Thor
  SM-78, PGM-19A Jupiter
Used W-34 "Python" as fission primary
W-50 LANL 60 kT (Y1), 200 kT (Y2), 400 kT (Y3)   M14, MGM-31A/B Pershing
  XLIM-49A Nike Zeus B
  [HSM-80A, LGM-30A Minuteman]
  [ASM-N-x Hopi]
Used W-44 "Tsetse" as fission primary
[W-51] LLNL 22 T   [GAR-11, AIM-26 Falcon]
  [M388 Projectile for M28/M29 Davy Crockett]
XW-51 was transferred to LANL and redesignated XW-54
W-52 LANL 200 kT   SSM-A-27, M15, MGM-29A Sergeant Used "Boa" (see W-30) as fission primary
MK-53
W-53
LANL 9 MT - 10 MT MK-53 Bomb:
  B-47B/E Stratojet
  B-52 Stratofortress
  B-58 Hustler (BA-53Y1 in BLU-2/B pod)
W-53 Warhead:
  SM-68B, LGM-25C Titan II
 
W-54 LANL 250 T (GAR-11)
10 T, 20 T (M388)
10 T - 1 kT (SADM)
  GAR-11, AIM-26A Falcon
  M388 Projectile for M28/M29 Davy Crockett
  M129/M159 SADM
SADM (Special Atomic Demolition Munition) was also known as B-54
W-55 LLNL 250 kT   UUM-44A Subroc Used "Kinglet" fission primary; some sources erroneously quote a low kiloton yield (1 - 5 kT)
W-56 LLNL 1.2 MT   HSM-80B/F, LGM-30B/F Minuteman I/II (Mk.11 RV) Nicknamed "Fife"; design based on W-47
MK-57 LANL 5 kT - 20 kT   B-52 Stratofortress
  F-100D/F Super Sabre
  F-104C/G Starfighter
  F-105 Thunderchief
  F/FB-111 Aardvark
  F-4C/D/E Phantom II
  A3D-2, A-3B Skywarrior
  A4D-2/5, A-4B/C/E/J/M Skyhawk
  A3J-1, A-5A Vigilante
  A2F, A-6 Intruder
  A-7 Corsair II
  F/A-18 Hornet
  P2V-5F/7, P-2E/H Neptune
  P-3 Orion
  S2F-1/2/3/3S, S-2A/C/D/E Tracker
  S-3 Viking
  SH-3D/H Sea King
Used W-44 "Tsetse" as fission primary
W-58 LLNL 200 kT   UGM-27C Polaris A3 Used "Kinglet" fission primary (see W-55)
W-59 LANL 800 kT, 1.2 MT   HSM-80A, LGM-30A Minuteman I (Mk.5 RV)
  [GAM-87, AGM-48 Skybolt]
Used W-44 "Tsetse" as fission primary
[W-60] LLNL (low)   [SAM-N-8, RIM-50 Typhon LR]  
B-61 LANL 10 kT - 300 kT (Mod 0/1/7)
10 kT - 150 kT (Mod 2/5)
300 T, 1.5 kT, 60 kT, 170 kT (Mod 3)
300 T, 1.5 kT, 10 kT, 45 kT (Mod 4)
300 T, 5 kT, 10 kT, 80 kT (Mod 10)
1.7 kT - 300 kT (Mod 11)
300 T, 1.5 kT, 10 kT, 50 kT (Mod 12)
  B-52 Stratofortress
  B-1B Lancer
  B-2A Spirit
  F-100D/F Super Sabre
  F-104C/G Starfighter
  F-105 Thunderchief
  F/FB-111 Aardvark
  F-117A Nighthawk
  F-4C/D/E Phantom II
  F-15E Eagle
  F-16 Fighting Falcon
  A4D-2/5, A-4B/C/E/J/M Skyhawk
  A2F, A-6 Intruder
  A-7 Corsair II
  F/A-18 Hornet
Also known as MK/B-61
W-62 LLNL 170 kT   LGM-30G Minuteman III (Mk.12 RV)
  [UGM-73 Poseidon C3]
W-62/Poseidon was cancelled in favour of W-68
[W-63] LLNL     [MGM-52 Lance] Enhanced Radiation ("Neutron Bomb") warhead; cancelled in favour of W-70
[W-64] LANL     [MGM-52 Lance] Enhanced Radiation ("Neutron Bomb") warhead; cancelled in favour of W-63
[W-65] LLNL     [LIM-100(?) Sprint] Enhanced Radiation ("Neutron Bomb") warhead; cancelled in favour of W-66
W-66 LANL 1 kT   LIM-100(?) Sprint Enhanced Radiation ("Neutron Bomb") warhead
[W-67] LANL 150 kT   [LGM-30G Minuteman III]
  [UGM-73 Poseidon]
Cancelled in favour of W-62 (Minuteman) and W-68 (Poseidon)
W-68 LLNL 40 kT - 50 kT   UGM-73A Poseidon C3  
W-69 LANL 170 kT - 200 kT   AGM-69A SRAM  
W-70 LLNL 1 kT - 100 kT (Mod 0/1/2)
1 kT (Mod 3)
  MGM-52C Lance Mod 3 is the Enhanced Radiation ("Neutron Bomb") version
W-71 LLNL 5 MT   LIM-49A Spartan  
W-72 LANL 625 T   AGM-62 Walleye MK 6 MOD 0 Modified from retired W-54 warheads
[W-73] LANL     [ASM-N-11, AGM-53A Condor] Derived from MK/B-61
[W-74] LANL > 100 T   [155 mm Artillery Shell] Cancelled in favour of W-82
[W-75] LLNL > 100 T   [8" Artillery Shell] Similar to W-74; cancelled in favour of W-79
W-76 LANL 90 kT - 100 kT   UGM-96A Trident  
[B-77] LLNL 1 MT   Cancelled in favour of B-83
W-78 LANL 335 kT - 350 kT   LGM-30G Minuteman III (Mk.12A RV) Derived from W-50
W-79 LLNL 100 T - 1.1 kT (Mod 0)
100 T - 0.8 kT (Mod 1)
  XM753 8" Artillery Shell Mod 1 has Enhanced Radiation ("Neutron Bomb") option
W-80 LANL 5 kT - 200 kT (W-80-0)
5 kT - 150 kT (W-80-1)
  BGM/RGM/UGM-109A Tomahawk (W-80-0)
  AGM-86B ALCM (W-80-1)
  AGM-129A ACM (W-80-1)
Derived from MK/B-61
[W-81] LANL 3 kT - 4 kT   [RIM-67 Standard SM-2 (ER)] Variant of MK/B-61
W-82 LLNL < 2 kT   XM785 155 mm Artillery Shell Similar to W-79
B-83 LLNL 1.2 MT   B-52 Stratofortress
  B-1B Lancer
  B-2A Spirit
  FB-111A Aardvark
 
W-84 LLNL 200 T - 150 kT   BGM-109G Gryphon Derived from MK/B-61 Mod 3/4
W-85 LANL 5 kT - 50 kT   MGM-31C Pershing II Derived from MK/B-61 Mod 3/4; was recycled after retirement into B-61 Mod 10
[W-86] LANL     [MGM-31C Pershing II] Earth-penetrating warhead
W-87 LLNL 300 kT (W-87-0)
475 kT (W-87-1)
  LGM-118A Peacekeeper (W-87-0)
  [MGM-134 Midgetman (W-87-1)]
 
W-88 LANL 475 kT   UGM-133A Trident II (Mk.5 RV)  
[W-89] LLNL 200 kT   [RUM/UUM-125A Sea Lance ASWSOW]
  [AGM-131A SRAM II]
 
[B-90] LANL 200 kT   NDSB (Nuclear Depth/Strike Bomb)
[W-91] LANL 10 kT, 100 kT   [AGM-131B SRAM-T]  
[W-92] LANL low kT(?)  
W-93 LANL TBD   UGM-133A Trident II (Mk.7 RV) Planned new strategic warhead

3 Sources

In no particular order:

[1] Chuck Hansen: "Swords of Armageddon", 1995
[2] James N. Gibson: "Nuclear Weapons of the United States", Schiffer Publishing Ltd, 1996
[3] Stephen I. Schwartz (ed.): "Atomic Audit: The Costs and Consequences of U.S. Nuclear Weapons Since 1940", Brookings Institution Press, 1998





Comments and corrections to: Andreas Parsch



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Last Updated: 12 December 2023