Small Diameter Bomb (SDB)

Product Type:

Guided Air-to-Surface Weapon

Using Service (US):

Air Force (USAF) and Navy

Program Status:

Low Rate Initial Production (GBU-53 SDB-II)

Prime Contractor:

(SDB-I & FLM) The Boeing Company
(SDB-II) Raytheon Company

The GBU-39 Small Diameter Bomb (SDB-I)

About the Small Diameter Bomb:

The Small Diameter Bomb is a system of guided bombs designed to provide a conventional small sized, precision guided, standoff air-to-ground weapon that can be delivered from both fighters and bombers. The system employs a BRU-61/A smart pneumatic carriage capable of carrying four 250-pound class guided air-to-surface munitions capable of destroying high-priority fixed and stationary targets from fighters and bombers in internal bays or on external hardpoints.

The advantages of the SDB System - compared to systems that have a single 1,000-pound or 2,000-pound weapon - are increased aircraft loadout, smaller logistical footprint, decreased collateral damage, and improved aircraft sortie generation times. The Small Diameter Bomb (SDB) is a joint U.S. Air Force and U.S. Navy program (led by the Air Force).

The Boeing GBU-39/B SDB-I is a fixed-target attack weapon, whereas the new Raytheon GBU-53/B SDB-II incorporates a tri-mode seeker and data link for use against moving targets. The SDB-II will be compatible with the BRU-61/A miniature munitions carriage and the CNU-660/E carriage system. The SDB-II can hit targets from a range of greater than 40 nautical miles. It has a powerful warhead capable of destroying armored targets while, at the same time, keeping collateral damage to a minimum. A third SDB, the Boeing GBU-40/B Focused Lethality Munition (FLM), is a fixed-target attack weapon similar to SDB-I, but a variant that increases the near field blast while decreasing collateral damage further.

In October 2013, Raytheon and the U.S. Air Force successfully completed a series of test flights with the GBU-53/B SDB-II. The DoD plans to purchase a total of 17,000 SDB-II weapons, including 12,000 for the Air Force and 5,000 for the Navy. Low Rate Initial Production (LRIP) commenced in FY 2014.


The GBU-39 SDB-I is fielded on the B-1B Lancer, the B-2A Spirit, the F-15E Strike Eagle, the F-16 Fighting Falcon, the F-22 Raptor, and is currently being integrated on the F-35 Lightning II.

The GBU-39 SDB-II will be fielded on the F-15E Strike Eagle and the F-35 Lightning II. Objective aircraft include the B-1B Lancer, the B-2A Spirit, the B-52 Stratofortress, the F-16 Fighting Falcon, the F/A-18E/F Super Hornet, the F-22 Raptor, and the MQ-9 Reaper. The AC-130 Gunship is being considered as an additional objective platform.

Price/Unit Cost:

The unit cost of the GBU-53/B SDB-II is $239,000 per All-Up Round (in FY 2014).

Total Cost - Life of Program (LoP):

The total procurement cost of the SDB-II program is $2.56 billion (official DoD estimate) + $1.65 billion in research and development (RDT&E) funds, which means the total estimated program cost is $4.21 billion (numbers are aggregated annual funds spent over the life of the program and no price/inflation adjustment was made).


The mission of the Small Diameter Bomb is to destroy targets from a medium-range standoff position deliverable by both fighters and bombers, with higher loadout and less collateral damage compared to other weapons.

FY 2014 DoD Program:

FY 2014 begins Low Rate Initial Production (LRIP 1) purchases of the GBU-53 SDB-II for use against moving and relocatable targets as well as fixed targets. In FY 14, the Air Force will purchase 144 GBU-53s at a cost of $36.0 million. FY 14 also provides for $138.3M in RDT&E funds.

FY 2015 DoD Program:

FY 2015 continues purchases of the GBU-53 SDB-II (LRIP 2). In FY 15, the Air Force will purchase 246 GBU-53s, containers, training equipment required for weapon handling and maintenance, software maintenance, and test assets and support for reliability testing at a total procurement cost of $70.6 million. Training equipment includes Weapon Load Crew Trainers, Conventional Maintenance Munitions Trainers, and Practical Explosive Ordinance Disposal System Trainers. FY 15 also provides for $140.6M in RDT&E funds.

For more information, click to see the FY 2015 USAF SDB-II Budget.

Source: U.S. Department of Defense (DoD), The Boeing Company,
and Raytheon Co.

Specifications Applications DoD Spending FY2015 Budget

Last Update: November 10, 2014.

By Joakim Kasper Oestergaard Balle /// (

External Resources:

Boeing's SDB Site: Small Diameter Bomb SDB-I

Raytheon's SDB Site: Small Diameter Bomb SDB-II

YouTube: Small Diameter Bomb Videos | YouTube

Fact Sheet: Boeing | GBU-39/B SDB-I Fact Sheet
Fact Sheet: Boeing | GBU-40/B FLM Fact Sheet
Fact Sheet: Cobham | BRU-61/A Fact Sheet

Total SDB-II Program Cost:

 $4.21 billion  ($2.56B procurement + $1.65B RDT&E)

GBU-53 SDB-II Procurement Objective:

  17,000  (USAF: 12,000 / Navy: 5,000)

SDB U.S. Defense Budget Charts:

DoD Spending on the GBU-39/53 Small Diameter Bomb in FY 2011, FY 2012, FY 2013, FY 2014 and FY 2015
DoD Purchases of GBU-53 Small Diameter Bombs (SDB-II) in FY 2011, FY 2012, FY 2013, FY 2014 and FY 2015
Defense Budget Data

Go to Top

DoD Spending, Procurement and RDT&E: FY 2011/12/13 + Budget for FYs 2014 + 2015

DoD Defense Spending, Procurement, Modifications, Spares, and RDT&E for the GBU-39/40 SDB-I Small Diameter Bomb and GBU-53 SDB-II Small Diameter Bomb

Download Official U.S. Department of Defense (DoD) Budget Data:

GBU-53 SDB-II Purchases (USAF) GBU-39 SDB-I Modifications (USAF)

Specifications: Small Diameter Bomb

Go to Top

Specifications | GBU-39/B Small Diameter Bomb (SDB-I)

Primary Function: Guided air-to-surface weapon
Prime Contractor: The Boeing Co.
Length: 70.8 in ( m)
Width: 7.5 in ( cm)
Weight: 285 lbs (129 kg)
Range: More than 60 nm/69 miles (111 km)
Guidance System: Global Positioning System/Inertial Navigation System
Warhead: 206 lbs (93 kg) blast fragmentation able to penetrate more than 3 feet of steel reinforced concrete
Price/Unit Cost: $40,000 (in 2011)
Initial Operational Capability: October 2006

Specifications | GBU-53/B Small Diameter Bomb (SDB-II)

Primary Function: Guided air-to-surface weapon
Prime Contractor: Raytheon Co.
Weight: 250 lbs (113 kg)
Range: Unknown
Guidance System: Global Positioning System/Inertial Navigation System
Seeker: Tri-mode: Millimeter-wave (MMW) radar, uncooled imaging Infrared (IIR), and Semi-Active Laser (SAL)
Price/Unit Cost: $239,000 per All-Up Round (in FY 2014)
Initial Operational Capability: Unknown - The DoD will purchase the GBU-53/B starting FY 2014.

Specifications | BRU-61/A Smart Pneumatic Carriage

Primary Function: Pneumatic Bomb Carriage
Manufacturer: Cobham Mission Equipment
Length: 143 in (3.63 m)
Width: 16 in (40.6 cm)
Height: 16 in (40.6 cm)
Weight: 320 lbs (145 kg); 1,460 pounds (664 kg) loaded with 4x GBU-39/B
Payload: 4x Small Diameter Bombs
Price/Unit Cost: Unknown
Initial Operational Capability: October 2006

Defense Program

Aircraft Programs Missile Programs Space Programs Shipbuilding Programs Vehicle Programs