Dry Ice for Shipping — Heat-Leak Estimate

Dry ice sublimates near −78.5 °C at atmospheric pressure. This model estimates wall heat leak and theoretical ice consumption from box geometry, illustrative conductivity, ambient temperature and duration. It does not establish a validated pack-out or guarantee product temperature.

How to use this tool

1. Choose US or metric units and enter the inside length, width and height of the cooler.
2. Enter the wall thickness and pick the insulation material.
3. Enter the expected average outside temperature along the route.
4. Enter the transit time and the extra hours you want to cover delays.

Formula

Q = k × ΔT × (A ÷ t + 0.54 × E + 1.2 × t); dry ice per day = Q × 86,400 ÷ 571,000 kg

Q is the heat leak in watts, k the foam conductivity (0.035 W/m·K for EPS, 0.030 for XPS, 0.025 for polyurethane), ΔT the outside temperature minus −78.5 °C, A the inside surface area in m², t the wall thickness in m and E the total length of the 12 inside edges in m. These illustrative conductivities and approximate edge/corner shape factors assume uniform walls and steady surface temperatures. About 571 kJ sublimates 1 kg of dry ice.

Example

A 12 × 10 × 10 in cooler with 2 in EPS walls at 77 °F gives 0.035 × 103.5 × (8.636 + 1.756 + 0.061) ≈ 37.9 W, consuming 5.73 kg per day. For 24 hours of transit plus 12 hours of cushion, the modeled consumption is 8.6 kg (18.9 lb); a tested shipping configuration must set the packing quantity.