Free tool · ParaChill™ by Dharaksha
Cold chain packaging calculator: ice box size, gel packs and hold time
Tell us what you ship, how long it travels and how hot the route gets. In a second you get a recommended ParaChill™ mycelium ice box size and wall thickness, how many gel packs, ice or dry ice to pack, and how long the box holds cold compared with a thermocol (EPS) box of the same wall.
- Ice box size calculator
- Gel pack calculator
- Insulated box hold time calculator
- Thermocol alternative
Your estimate
Show the maths
How it works
Transparent physics, no black box
An insulated box warms up because heat conducts through its walls. The calculator uses the standard conduction formula and the latent heat of your coolant. It’s the same first-pass method packaging engineers use before a lab test.
1. Heat in through the walls
Q = k · A · ΔT / t. k is the wall’s thermal conductivity, A the wall area, ΔT the outside temperature minus the product temperature, and t the wall thickness.
2. Coolant soaks it up
Gel packs and ice absorb heat as they melt (latent heat). Dry ice absorbs it as it turns to gas. Coolant needed = heat in × hours ÷ latent heat.
3. Mycelium vs thermocol
ParaChill™ mycelium has k = 0.032 W/m·K against 0.0365 W/m·K for thermocol (EPS). Less heat gets in, so the same coolant lasts longer. In cold-hold trials ParaChill™ stays below 8 °C for about 20% longer.
| Assumption | Value used |
|---|---|
| Thermal conductivity | ParaChill™ mycelium 0.032 W/m·K; thermocol (EPS) 0.0365 W/m·K |
| Box shape | Treated as a cube; wall area taken at mid-wall, 6 × (side + wall)² |
| Lid and edge allowance | +15% heat in for lid seams and corners |
| Safety margin | Coolant sized for 20% more time than your transit |
| Gel packs | About 300 kJ/kg absorbed melting at 0 °C; 1.0 kg per litre; 500 g packs |
| Water ice | 334 kJ/kg at 0 °C; 0.92 kg per litre |
| Dry ice | 571 kJ/kg on subliming at −78.5 °C; pellets about 0.9 kg per litre |
| Product | Pre-cooled to its target temperature before packing; packed density per product type |
| Ignored (conservative) | Extra cold stored in packs frozen below 0 °C, and the product’s own thermal mass |
| Not modelled | Direct sun, lid openings and door-to-door handling delays. Add hours for these. |
Conduction alone gives ParaChill™ about 14% longer hold than EPS at the same wall (0.0365 ÷ 0.032). Our trials show about 20%, helped by the sealed surface and snug lid. The calculator uses the more conservative conduction figure.
Box sizes
ParaChill™ mycelium ice boxes: 2 L to 50 L, or custom
The calculator picks the smallest standard ParaChill™ box that fits your product plus its coolant. Larger loads get a custom size, or several 50 L boxes. Every box is grown from agricultural residue and mycelium, is reusable across trips and returns to soil at end of life. It’s a thermocol alternative that performs better, not just greener.
2 L
Samples, single vials and compact pharma packs.
5 L
Short-haul food, dairy and diagnostic shipments.
37 L
Standard cold chain for pharma, seafood and meal kits.
50 L & custom
Bulk loads, longer routes and made-to-measure boxes.
See the full range on our cold chain packaging and ParaChill™ mycelium ice box pages, or see how much thermocol the world makes on the live thermocol tracker. Designing a carton or mailer as well? Make a free box template with a matching mycelium insert in the packaging dieline generator.
FAQ
Cold chain calculator: questions, answered
How do I calculate what size ice box I need?
Add your product volume to the volume of coolant it needs, then allow about 15% for packing gaps. The coolant depends on how much heat leaks in during transit, so the box size and the coolant are worked out together. The calculator does this for you and picks the smallest ParaChill™ box (2, 5, 37 or 50 litres) that fits.
How many gel packs do I need for 24 hours?
It depends on the box, the wall and the heat outside. For example, 6 kg of vaccines in 40 °C summer heat for 24 hours works out at about 9.5 kg of gel packs (19 packs of 500 g) in a 37 L ParaChill™ box with a 40 mm wall. Enter your own numbers above for an estimate, then confirm with a route trial.
How is insulated box hold time calculated?
Hold time = coolant mass × latent heat ÷ heat leaking in. Heat leaking in = k × wall area × temperature difference ÷ wall thickness. A lower k (better insulation), a thicker wall or more coolant all extend the hold time.
Is mycelium a good thermocol alternative for cold chain?
Yes. ParaChill™ mycelium has a thermal conductivity of 0.032 W/m·K against 0.0365 W/m·K for thermocol (EPS), and holds below 8 °C for about 20% longer in trials. It is reusable, plastic-free and biodegradable.
Can I use dry ice in a ParaChill™ box?
Yes, for frozen goods and ice cream. Dry ice gives off CO₂ gas, so the box must not be airtight, and air shipments need UN1845 dry ice labelling. Never use dry ice for 2–8 °C pharma or chocolate, because it would freeze them.
How accurate is this calculator?
It is a first-pass engineering estimate, usually within the right size band. Real routes add sun, door openings and delays, so we size coolant with a 20% margin and recommend validating on your own route. We send a free sample for exactly that.
Next step
Test ParaChill™ on your own route, free
Send us your result (use “Copy my spec”) and we’ll recommend the exact box, wall and pack-out, then ship a free sample for your temperature trial.