Strategic Bombardment Calculator
(Created 7 April 2017)
(Updated 20 November 2017)

Green = User input boxes.
Red = System output boxes.

NOTES:

Circular Error Probable (CEP): This is the radius in which 50% of all weapons launched/fired/dropped would land. The 95% Radius (R95) is the radius in which pretty much all weapons would land. Converting to/from R95 to CEP is very simple: Multiply R95 by 0.48 to get CEP. Divide CEP by 2.1 to get R95.

Probability of Kill (PKill): Calculation defaults assume an 85% PKill desired against the target. This is a good balance between "target destruction assurance" and "bouncing the rubble".

Lethal Radius: For conventional weapons, the lethal radius has been set to a default assumption of 15 meters, which is a good rule of thumb for 500 pound GP bombs against a variety of civilian structures. A more detailed calculation of conventional blast effects is below, using the charge weight equivalence in TNT run through a nuclear weapons effects calculator to get the 20 PSI radius.

Bomb Type

Charge Wt (lbs)

Explosive Charge

Charge TNT Equivalence

Charge TNT
Equiv. Wt. (lbs)

20 PSI Damage Radius (meters)

50 lb GP (British WWII)

12.5

TNT

1

12.5

5

120 lb GP (British WWII)

30

TNT

1

30

7

250 lb GP (British WWII)

72.5

TNT

1

72.5

9

500 lb MC (British WWII)

140

TNT

1

140

11

1000 lb MC (British WWII)

330

Amatol

0.91

300.3

14

2000 lb HC (British WWII)

1400

Amatol

0.91

1274

23

4000 lb HC (British WWII)

3040

Amatol

0.91

2766.4

30

8000 lb HC (British WWII)

5440

Amatol

0.91

4950.4

36

12000 lb HC (British WWII)

9600

Amatol

0.91

8736

43

12,000 lb MC (British Tallboy)

5200

Torpex

1.3

6760

40

22,000 lb MC (British Grand Slam)

9136

Torpex

1.3

11876.8

48

250 lb LD-GP Mk 81

96

Tritonal

1.18

113.28

10

500 lb LD-GP Mk 82

192

Tritonal

1.18

226.56

13

1000 lb LD-GP Mk 83

445

Tritonal

1.18

525.1

17

2000 lb LD-GP Mk 84

945

Tritonal

1.18

1115.1

22

For Nuclear Weapons, the Lethal Radius (LR) of various yields is dependent on the target hardness levels. A good rule of thumb for Nuclear LR's is below:

Nuclear Target Type

Hardness
(PSI)

20 KT Lethal Radius (m)

100 kt Lethal Radius (m)

200 kt Lethal Radius (m)

1 MT Lethal Radius (m)

2 MT Lethal Radius (m)

5 MT Lethal Radius (m)

10 MT Lethal Radius (m)

20 MT Lethal Radius (m)

Class 1 Target
(Very Hard Target)

5,000

77

132

166

284

358

485

611

770

Class 2 Target
(Hard Target)

2,000

105

179

225

385

485

659

830

1045

Class 3 Target
(Medium Hard Target)

500

166

284

358

611

770

1045

1317

1659

Class 4 Target
(Soft Target)

25

450

770

970

1659

2091

2838

3575

4504

Class 4 and it's attendant 25 PSI are not cited in the CBO study -- they are a reasonable extrapolation of target category classifications. Additionally, 20 PSI is enough to ensure near total 100% fatalities and destruction of almost all concrete structures; so it's good enough to stand in for an urban area in calculations.

If you need to compute a Lethal Radius for a specific nuclear weapons system, use the following inputs below:

Yield of weapon: kilotons and Target Hardness of: PSI. results in a Lethal Radius of meters.

System Reliability: This is the percentage of a chance that the weapon system will successfully function and reach the target area. NOTE: It is worth noting that in general public sources, the 17 October 1963 launch of a MINUTEMAN I was classified as a "success". This launch, classified CEDAR LAKE, was part of the Operational Test (OT) preceding induction of the Minuteman into SAC SIOP service and it actually missed the target by 24.26 nautical miles to the right and 781.37 nautical miles over.

Weapon Reliability: This is the percentage of a chance that the bomb/missile will successfully explode after it's been released at/near the target.

Bibliography:
Trident II missiles: capability, costs, and alternatives, Congressional Budget Office
Missile Procurement, Air Force, May 16, 1961 Hearings, AlternateWars.com.
Calculations relevant to Nuclear Exchanges, Big Book of Warfare
Wikipedia, CEP
Effectiveness of Bombs, ww2aircraft.net
Explosive Equivalencies, Wikipedia

Circular Error Probable (CEP): (m)
Lethal Radius (LR): (m)
System Reliability: (%)
Bomb/Weapon Reliability: (%)
Bombs/Weapons Per System:       

Desired Target PKill: (%)

Single Shot Prob. of Kill (SSPK): (%)
Terminal Prob. of Kill (TKP): (%)

Planes/Weapons Systems Needed:       
Bombs/Weapons Needed:       
Bombs/Weapons On Systems:       
Spare Bombs/Weapons:       

Kill Probability (KPN):       

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