Blast-Resistant Glazing Calculator

Glass laminate layup from blast threat level.

Charge weight (kg TNT)

Standoff distance (m)

Panel width (mm)

Panel height (mm)

Interlayer type (1-2)

Tab to move between fields

Peak pressure (kPa)

60.1

Glass ply thickness (mm)

Scaled distance Z (m/kg^⅓)6.46

Positive phase (ms)10.6

Impulse (kPa·ms)317

Number of glass plies2

Interlayer thickness (mm)1.52

Total build-up (mm)51.5

Panel weight (kg)386.4

GSA hazard level (1-4)3

How to Use This Calculator

Enter the TNT-equivalent charge weight (kg) and the standoff distance (m) from the charge to the glazing.
Enter the glass panel width and height (mm) and choose the interlayer type — PVB (standard) or SGP (SentryGlas, stiffer).
Review the calculated peak reflected pressure, positive phase duration, and impulse from the blast scaled distance.
Check the recommended glass ply thickness, number of plies, interlayer thickness, and total laminate build-up.
Verify the GSA/ISC hazard rating (1=Safe to 4=High) and use the estimated panel weight for structural sizing.

How the result changes with Standoff distance (m)

Charge weight (kg TNT): Equivalent TNT charge weight in kilograms. Car bomb ~100 kg, truck bomb ~1,000+ kg.
Standoff distance (m): Distance from the charge to the glazing face. Controlled by bollards, setbacks, etc.
Panel width (mm): Width of the individual glass panel.
Panel height (mm): Height of the individual glass panel.
Interlayer type (1-2): 1 = PVB (polyvinyl butyral, standard), 2 = SGP (SentryGlas Plus, higher stiffness).

Scaled distance Z (m/kg^⅓): Hopkinson-Cranz scaled distance. Lower values = more severe threat.
Peak pressure (kPa): Peak reflected overpressure at the glazing face.
Positive phase (ms): Duration of the positive pressure phase.
Impulse (kPa·ms): Reflected impulse (area under pressure-time curve).
Glass ply thickness (mm): Recommended thickness per glass ply (heat-strengthened).
Number of glass plies: Recommended number of glass plies in the laminate.
Interlayer thickness (mm): Total interlayer thickness for fragment retention.
Total build-up (mm): Total laminated glass thickness including interlayers.
Panel weight (kg): Estimated weight of the laminated glass panel.
GSA hazard level (1-4): Estimated GSA/ISC hazard rating: 1=Safe, 2=Very Low, 3=Low-Medium, 4=High risk.

Identify Input Parameters
4 parameters
Charge weight (kg TNT) = 100, Standoff distance (m) = 30, Panel width (mm) = 1500, Panel height (mm) = 2000 = 5 input(s) provided
Calculate Peak pressure
Peak pressure = 1772 / (z * z) + 114 / z
60.1 = 60.1
Calculate Glass ply thickness
25 = 25
Calculate Scaled distance Z
Scaled distance Z = standoffM / pow(chargeKg, 1 / 3)
6.46 = 6.46
Calculate Positive phase
Positive phase = 1.3 * pow(chargeKg, 1 / 3) * pow(z, 0.3)
10.6 = 10.6