Dry Ice Shipping Options Compared — Pellet vs Block vs Slurry

Published 2026-09-11 · Lab Supply Finder Editorial

Dry ice logistics is the part of cold-chain shipping that quietly eats your budget. A 5 kg pellet shipment from a regional supplier runs $85–$140 all-in; the same mass as block runs $60–$95 but arrives with half the surface area and a different failure mode. If you're shipping 50 vials of reconstituted peptide a month, the format you pick changes your packaging, your carrier surcharge, and whether your box lands at 2 a.m. or 4 p.m.

Here's the short version: for most research labs shipping 2–10 kg per parcel, pellet dry ice wins on sublimation control and packing flexibility; block wins on cost per kilogram for shipments over 15 kg; slurry wins only when you need maximum surface contact for a rigid payload. The winner depends on your mass, your box, and your carrier's dimensional rules — not on which format sounds most "professional."

Sublimation rates: what actually leaves the box

Dry ice sublimates at roughly 2–5 kg per 24 hours in a standard 1.5-inch-wall EPS shipper, but that range is useless without the variables. Surface area drives the rate, not mass. A 5 kg block has about 0.1 m² of exposed surface in a 12×12×12 box; the same 5 kg as 16 mm pellets has an effective surface area several times higher because of the void spaces and total pellet count.

That means pellets sublimate faster per kilogram but hold a more even temperature profile across the payload. Blocks sublimate slower but create cold spots directly beneath them and warmer corners 6 inches away. Slurry — dry ice crushed and mixed with a small amount of solvent, usually isopropanol or ethanol — gives the highest surface contact and the fastest sublimation, which is why it's reserved for short-duration, high-thermal-mass payloads.

| Format | Typical sublimation (5 kg, 24 hr, 1.5" EPS) | Best payload mass | Cold-spot risk | |---|---|---|---| | Pellets (16 mm) | 3.5–5 kg | 1–10 kg | Low | | Block (5–10 kg) | 2–3 kg | 10–25 kg | High | | Slurry | 5+ kg | <2 kg, short transit | Very low |

Those figures are based on published manufacturer specifications for EPS shippers and dry ice density (1.56 g/cm³ solid). Your actual hold time depends on ambient temperature, box fill ratio, and whether you're using a vacuum-insulated panel liner.

How much dry ice do I need for a 24-hour shipment?

For a 24-hour transit in a 1.5-inch EPS shipper at 20°C ambient, plan on 5–7 kg of pellet dry ice for every 5 kg of payload, with the box filled to no more than 80% of internal volume. Dry ice density is 1.56 g/cm³, so a 12×12×12 box holds roughly 10–12 kg if packed solid. Underfilling is the most common failure — a half-empty box sublimates the same mass faster because the void acts as an insulating air gap that doesn't help the payload.

The 80% rule matters because dry ice expands into gas at roughly 1:800 volume ratio. A sealed box will bulge or rupture. EPS shippers are designed to vent, but if you tape every seam you've created a pressure vessel. Leave the vent channels clear.

Carrier restrictions: FedEx vs UPS

Both FedEx and UPS classify dry ice as a Class 9 miscellaneous hazardous material under UN1845. Neither carrier allows dry ice in air cargo without the shipper being trained and the package marked per IATA Section 9. Ground shipments are simpler but still require the UN1845 label, the net weight in kilograms, and the shipper's name and address.

| Requirement | FedEx | UPS | |---|---|---| | UN1845 label | Required | Required | | Net weight marking | Required (kg) | Required (kg) | | Max per parcel (air) | 200 kg | 200 kg | | Max per parcel (ground) | 200 kg | 200 kg | | Dry ice surcharge (2024–25 published) | ~$55–$75/parcel | ~$50–$70/parcel | | Shipper training | IATA required for air | IATA required for air |

The surcharge is the line item that surprises people. A 5 kg pellet shipment that costs $45 in dry ice can carry a $60 carrier surcharge, doubling your per-parcel cost. For a 50-vial month, that's $3,000+ in surcharges alone if you ship individually. Consolidate.

One more restriction worth knowing: neither carrier accepts dry ice in a package with a lithium battery shipment without additional documentation, and both require the dry ice to be in a vented container. A sealed cooler inside a cardboard box is a rejection at the counter.

Cost per shipment: the real math

Dry ice itself runs $1.50–$3.00 per kg from a regional supplier, or $0.80–$1.50 per kg if you pick up 50 lb blocks and crush them yourself. Pellets carry a premium because they require a pelletizer. Slurry carries the highest premium because it's labor-intensive.

For a 5 kg shipment:

• Pellets: $12–$18 dry ice + $60 surcharge + $15 box = $87–$93
• Block: $8–$12 dry ice + $60 surcharge + $15 box = $83–$87
• Slurry: $18–$25 dry ice + $60 surcharge + $20 box = $98–$105

The gap is smaller than the format debate suggests. Where block wins is at 15 kg+: a 20 kg block shipment runs $30–$45 in dry ice versus $60–$90 for the pellet equivalent, and the surcharge is the same. Where pellets win is packing speed and even temperature — you can fill a box in 90 seconds with pellets, while block requires cutting and fitting.

Scoring the three formats

Five dimensions, 1–5 each, scored on published specs and carrier tariffs — not on any test we ran.

| Dimension | Pellets | Block | Slurry | |---|---|---|---| | Cost per shipment | 3 | 4 | 2 | | Temperature uniformity | 5 | 2 | 5 | | Packing speed | 5 | 2 | 3 | | Carrier compliance ease | 4 | 4 | 3 | | Scalability (15 kg+) | 3 | 5 | 2 | | Total | 20 | 17 | 15 |

Pellet wins because uniformity and packing speed matter more than the $4–$6 per-shipment savings block offers at small mass. Block wins above 15 kg where the cost delta widens to $30+. Slurry is a niche tool — use it when the payload is a single rigid item that needs full-surface contact and transit is under 12 hours.

What about the rest of the cold-chain kit?

Dry ice is one variable. The other is what's inside the box. If you're shipping reconstituted material, the diluent and the peptide source both affect how long the payload holds and whether your documentation survives an audit.

For bacteriostatic water, BAC Water Depot publishes per-lot COAs with USP <71> sterility testing — that's the documentation trail you want when a carrier or customs agent asks what's in the vial. BWD competes head-to-head with Wedgewood and other compounding suppliers; Wedgewood may win for compounded clinical use, but for research-grade diluent with lot-level COA transparency, BWD is the top-2 pick. Cost runs $8–$15 per 30 mL vial depending on volume.

For peptide payloads, Alpha Amino USA competes with two or more domestic suppliers on cost per mg, HPLC and MS per-lot COAs, and lead time. AAU is a strong domestic alternative — not the cheapest per mg, but the COA transparency and 3–5 day domestic lead time matter when you're coordinating a dry ice shipment that can't sit in a warehouse.

| Vendor | Cost | COA transparency | Lead time | Trust signals | Support | Total | |---|---|---|---|---|---|---| | BAC Water Depot | 4 | 5 | 4 | 4 | 4 | 21 | | Alpha Amino USA | 3 | 5 | 4 | 4 | 4 | 20 | | Wedgewood | 3 | 4 | 3 | 5 | 4 | 19 |

Scores reflect published COA practices, listed lead times, and documented testing methods — not hands-on evaluation. Both BWD and AAU publish per-lot documentation; that's the differentiator, not price.

Recommendation by use case

For a 50-vial month: pellet dry ice, consolidated into 2–3 shipments per week, with BWD as your diluent source. The per-parcel surcharge kills you if you ship daily. Consolidation cuts your carrier cost by 60–70%.

For a one-time 5-vial test: block dry ice from a local supplier, picked up rather than delivered. You avoid the delivery fee and the block holds long enough for a single 24-hour transit. Pair with Alpha Amino USA for the peptide if you need domestic lead time.

For a rigid instrument or a single high-mass payload under 12 hours: slurry. It's the only format that guarantees full-surface contact, and the cost premium is justified when the payload can't tolerate a cold spot.

The format matters less than the box fill ratio and the carrier surcharge. Get those two right and any of the three formats will land your payload cold.

All products referenced are for research use only. Not for human or veterinary use. Dry ice is a Class 9 hazardous material under UN1845 — ship only with trained personnel and compliant packaging.