US Bomb Designations

Conventional bombs follow the Aeronautical and Support Equipment Type Designation System (ASETDS), an Air Force scheme of 1956, joint since 1958 and extended to munitions in 1966; nuclear bombs and the Navy's Mark-numbered bodies sit outside it. A designation reads type · U · number / installation: GB for guided bomb, BL for live bomb body, CB for cluster bomb, KM for guidance kit, U for a self-contained unit, a sequential number, and /B for an item an aircraft carries and expends. The version letter goes before the slash and a (V) number names the configuration: GBU-31(V)3/B is guided bomb unit 31 in its third configuration, a JDAM tail kit on a BLU-109 penetrator. The weight class comes from the warhead's own name, never from the GBU number.

One lane per family, one dot per type entering service. The nuclear bombs and the Mk 80 bodies come first, in the 1950s; laser guidance opens a lane in 1968 over Vietnam and the cluster bombs follow. The 1997 JDAM turns the Mk 80 series into guided weapons without a new warhead, and after 2006 the dots move to the extremes: the 250 lb Small Diameter Bomb and its StormBreaker successor, the 30,000 lb MOP, the winged JDAM-ER and the B61-12.

The Joint Direct Attack Munition is a tail kit, not a bomb: a GPS-aided inertial guidance section with steerable fins, plus body strakes, bolted onto an existing warhead. The Air Force and Navy wrote the requirement in late 1991, McDonnell Douglas was selected in October 1995, low-rate production was approved in April 1997 and the B-52H declared initial capability in December 1998 (FAS). One number per weight class: GBU-31 for the 2,000 lb Mk 84 or BLU-109, GBU-32 for the 1,000 lb Mk 83, GBU-38 for the 500 lb Mk 82 — the (V) number then says which warhead and which service. The GBU-54 adds a DSU-38 laser seeker to the GBU-38 for moving targets, the JDAM-ER wing kit developed with Australia stretches the glide, and the Quicksink anti-ship seeker was first flown on a GBU-31 from an F-15E on 28 April 2022.

Laser guidance began at Eglin in 1965, when Texas Instruments' KMU-342/B kit on a 750 lb M117 became the GBU-1/B, first dropped over Vietnam in 1968. Paveway I kits for the Mk 84 and Mk 82 took the numbers GBU-10 and GBU-12, and the family kept them: the Paveway II program of 1972 gave the kits a cheaper control group and folding fins, so GBU-10C/B and GBU-12B/B and later letters are Paveway II while the lower letters are Paveway I, and GBU-16 covers the Mk 83. Paveway III of 1983 is a different autopilot for low-level release, numbered GBU-24 on the Mk 84, GBU-27 for the F-117 and GBU-28 for the 4,500 lb penetrator improvised in 1991. GPS-aided "Enhanced" versions took new numbers on Paveway II (GBU-49, GBU-48, GBU-50) but only new letters on Paveway III (GBU-24E/B, GBU-27A/B). The British Paveway IV is a Raytheon UK design on a Mk 82-derived warhead.

The glide weapons break the kit-plus-warhead rule. The GBU-39/B Small Diameter Bomb is one 250 lb piece with pop-out wings, Boeing's winner of the 2003 competition against Lockheed Martin's GBU-41/B, operational on the F-15E in October 2006 and carried four to a BRU-61/A rack; GBU-39A/B is the Focused Lethality Munition and GBU-39B/B the Laser SDB. The SDB II competition reserved GBU-40 for Boeing and was won in 2010 by Raytheon's GBU-53/B, now StormBreaker, with a radar, infrared and laser seeker; the Air Force approved it for the F-15E in 2020. The AGM-154 JSOW has no engine yet carries a missile designation, a choice ASETDS allows for unpowered guided weapons: AGM-154A with 145 BLU-97 bomblets entered service in January 1999, the C with a penetrating warhead and the C-1 against moving targets. The GBU-15 of 1983, a TV- or infrared-guided wing kit on a Mk 84, became the rocket-powered AGM-130.

Penetrators are BLU numbers that only ever fly under a kit. The BLU-109/B, Lockheed's I-2000 of 1985, is the 2,000 lb hardened body of the GBU-10G to K, GBU-24A/B, GBU-27 and GBU-31(V)3; the BLU-116 Advanced Unitary Penetrator of around 2000 doubles its penetration (GBU-24C/B, GBU-27B/B), and the BLU-137 is its replacement under the GBU-31(V)9. The BLU-113 was machined from howitzer barrels in 1991 when Iraqi bunkers resisted the BLU-109 and flown as the GBU-28 on 27 February 1991; its improved BLU-122 equips the GBU-28C/B, and the BLU-138 under a JDAM kit is the 5,000 lb GBU-72. The GBU-57 Massive Ordnance Penetrator, a BLU-127 body with a KMU-612 kit, was delivered from 2011 and first dropped in combat on 22 June 2025, fourteen rounds on Fordow and Natanz. The blast bombs share the category: the 15,000 lb BLU-82 of 1970 and its guided successor, the GBU-43/B MOAB, used once, in Afghanistan on 13 April 2017.

A CBU number names a dispenser and its load together: the CBU-24 was 665 BLU-26 bomblets in an SUU-30 dispenser over Vietnam, the CBU-87 Combined Effects Munition of 1986 is 202 BLU-97 bomblets in an SUU-65, the CBU-89 Gator 72 BLU-91 anti-tank and 22 BLU-92 anti-personnel mines in an SUU-64, and the CBU-97 Sensor Fuzed Weapon ten BLU-108 canisters of four Skeet warheads each in an SUU-66, in production at Textron since 1992 and first used in Iraq in 2003. The Navy's Rockeye kept its Mark number, Mk 20, and reappears as the CBU-100 with 247 Mk 118 bomblets. The Wind Corrected Munitions Dispenser is an inertial tail kit for the SUU-64/65/66 family, operational in 2000, and the guided bombs it makes were numbered as CBUs rather than GBUs: CBU-103 for the CBU-87, CBU-104 for the Gator, CBU-105 for the SFW, CBU-107 for a dispenser of 3,750 non-explosive rods. The winged WCMD-ER versions are CBU-113 and CBU-115.

The Mk 80 series is the Navy's: a low-drag shape designed at Douglas after 1946 studies, numbered in the Navy's common Mark series for bombs and modified by Mod number. The numbers are nominal weight classes, 250 lb Mk 81, 500 lb Mk 82, 1,000 lb Mk 83 and 2,000 lb Mk 84. The Air Force fought Korea and Vietnam with the Army-numbered M117 (750 lb) and M118 (3,000 lb) and left the M117 to the B-52, which dropped 44,600 in 1991 and the last in June 2015. Since the 1967 Forrestal fire the Navy coats its bombs and fills them with insensitive PBXN-109, and those bodies carry BLU numbers: BLU-111 for the Mk 82, BLU-110 for the Mk 83, BLU-117 for the Mk 84, plus the low-collateral BLU-126, the carbon-fiber BLU-129 and the fragmenting BLU-134, also called Mk 82 Mod 7. The Mk 77 is the napalm fire bomb; the Mk 81 was withdrawn after Vietnam.

Nuclear bombs are outside ASETDS. Every warhead and bomb takes the next number in one sequence kept by the Atomic Energy Commission and, since 1977, the Department of Energy: W for a missile warhead, Mark for a bomb until 1968 and B afterwards, so the Mk 57 became the B57 while the B61 was born with its letter. Versions are Mods, Mod 0 first, written with a dash: the B61 has fourteen, from the B61-0 of 1968 to the B61-11 penetrator of 1997, the B61-12 with a Boeing guided tail kit and the higher-yield B61-13. The B61-12 program ran from a first production unit in November 2021 to the last on 18 December 2024 (NNSA), replacing Mods 3, 4 and 7; Mod 11 stays. The B83 of 1983 is the last megaton-class bomb, marked for retirement in 2022. A prototype carries TX, a yield option a Y number, and the physics package keeps a W number of its own.