Heat Age
How cold storage changes the numbers
Time and temperature add up. See how cold storage changes the warmth a formula encounters before dispatch.
237:1
Modeled heat exposure before dispatch
1,956 ÷ 8.25 = 237.09
Degree-days above a 4°C reference.
Rounded to the nearest whole number.
How we measure heat exposure.
We measure warmth above our 4°C refrigeration reference in degree-days: one degree Celsius above that reference, for one day.
One day at 22°C
18 degrees above the reference, for one day. That adds 18 degree-days.
Thirty days at 22°C
The same temperature, more time. 18 × 30 adds 540 degree-days.
Time at 4°C
At the refrigeration reference, no warmth above 4°C is added to this measure.
Compare the two journeys.
Compare a room-temperature supply chain with Wild Ice’s cold-storage process. The tables show every input.
Adjust warehouse days to update the comparison and table. All other inputs stay fixed.
60-day warehouse stay
237.09:1
Modeled heat exposure before dispatch
1,956 ÷ 8.25 = 237.09
Room-temperature scenario ÷ Wild Ice scenario
Room-temperature scenario
Comparison assumptions for ingredients, production and inventory before dispatch.
| Stage | Temp. | Time | Degree- days |
|---|---|---|---|
| Ingredient receiving & storage | 22°C | 21 days | 378 |
| Formulation, filling & QC hold | 22°C | 10 days | 180 |
| Finished goods at manufacturer | 22°C | 14 days | 252 |
| Freight to brand warehouse | 26°C | 3 days | 66 |
| Brand warehouse / 3PL | 22°C | 60 days | 1,080 |
| Total degree-days | 1,956 | ||
Wild Ice scenario
Our 4°C storage practice, with the handling times used in this calculation.
| Stage | Temp. | Time | Degree- days |
|---|---|---|---|
| Ingredient receiving | 22°C | 2 hours | 1.5 |
| Ingredient cold storage | 4°C | 60 days | 0 |
| Formulation & filling | 22°C | 8 hours | 6 |
| Finished formula cold storage | 4°C | 14 days | 0 |
| Picking & packing | 22°C | 1 hour | 0.75 |
| Awaiting carrier pickup | 4°C | 12 hours | 0 |
| Total degree-days | 8.25 | ||
Where the assumptions come from
The room-temperature scenario uses 22°C for indoor stages and 26°C for freight, with 21, 10, 14, 3 and 60 days respectively. These are comparison inputs, rather than measured averages for every brand.
Wild Ice stores ingredients and finished formulas at 4°C before dispatch. The calculation uses 2 hours for receiving, 8 hours for production and 1 hour for packing at 22°C. The cold-storage periods are 60 days, 14 days and 12 hours; at 4°C they add zero to the above-reference total.
The room-temperature scenario ends with warehouse storage, while the Wild Ice scenario includes picking and packing. Final conventional order-packing time is left out of the 1,956 total. Both scenarios exclude customer delivery, retail display and storage at home.
A shipment-temperature study reported 26.2°C across its particular shipments. It provides context for the 26°C freight input; it does not establish a national annual average. Read the study below.
How to repeat the calculation
For each row, subtract 4 from the temperature, then multiply by the duration in days. Convert hours to days by dividing by 24. Add the rows for each scenario, then divide the room-temperature total by the Wild Ice total.
Room-temperature scenario at 60 warehouse days: 378 + 180 + 252 + 66 + 1,080 = 1,956.
Wild Ice: 1.5 + 0 + 6 + 0 + 0.75 + 0 = 8.25.
Comparison: 1,956 ÷ 8.25 = 237.09:1, rounded to 237:1.
For another warehouse duration, use 876 + (18 × warehouse days) for the room-temperature total. At or below 4°C, this measure adds zero degree-days. The download contains the 60-day warehouse inputs, including exact durations in hours.
Download the calculation (CSV)Care for what
you put in.
Explore Why Cold Cosmetic stability tests often use elevated temperatures to reveal changes in a formula sooner. Cold storage inhibits temperature-sensitive changes. We combine it with careful formulation because choosing useful ingredients and caring for them belong together.
We keep your order chilled until carrier pickup. It then travels by standard parcel delivery.
For everyday storage and travel, visit our FAQ.
Follow the evidence.
Shelf Life and Expiration Dating of Cosmetics
Explains factors that affect cosmetic shelf life, including temperature changes, air and sunlight, and advises keeping cosmetics away from heat.
Guidelines on Stability Testing of Cosmetic Products
Describes accelerated stability testing at elevated temperatures, often 37°C, 40°C or 45°C, with conditions selected for the formula. This supports why temperature matters; it does not validate the numerical Heat Age comparison.
Temperature exposure during shipment
A study of bone-matrix putty recorded an average internal temperature of 26.2°C across 72 shipments, with temperature spikes during delivery and handling. These observations provide context for our freight assumption.
Ascorbic acid stability in emulsified systems
Research at 20°C and 45°C shows why formulation matters alongside temperature: the studied emulsions provided different levels of protection against oxidation.
International packaging and shipping of vaccines
The worked example on page 75 uses degree-hours above a chosen temperature to compare exposure. Our skincare comparison uses the same kind of time-and-temperature measure, with a 4°C reference.
Last reviewed October 16, 2026