Stability Testing Schedule Calculator
Accelerated and real-time stability test design.
About this calculator
This calculator builds a cosmetic stability study plan from shelf-life targets and temperature assumptions using the Q10 acceleration rule. Acceleration Factor raises the Q10 input to the power of accelerated temperature minus storage temperature, divided by ten (lines 31-32). Accelerated Test Duration divides target shelf life months by that factor so the hot chamber run spans enough calendar time to mimic the label claim (line 35). Real-Time Pull Points counts standard months from zero through forty-eight that fall at or below target shelf life, adding the exact target month if it is not already in the list (lines 38-43). Accelerated Pull Points uses a shorter standard schedule capped by the accelerated duration (lines 46-49).
Storage Conditions counts real-time plus accelerated plus one freeze-thaw leg when cycles are greater than zero (lines 53-54). Total Pulls sums real-time, accelerated, and two freeze-thaw pulls when applicable (lines 54-56). Total Samples multiplies pulls by samples per pull; Total Tests multiplies samples by tests per sample (lines 57-58). Estimated Shelf Life multiplies accelerated duration back by the acceleration factor (line 61). Study Duration equals target shelf life months for the real-time leg (line 64).
Inputs
Results
Acceleration factor (×)
2.83
Accelerated test duration (months)
8.5
How to Use This Calculator
- Enter the target shelf life along with the accelerated and storage temperatures.
- Set the Q10 factor to match how sensitive your formula is to heat (2 for most cosmetics, 3-4 for sensitive formulas).
- Input samples per pull point, tests per sample, and freeze-thaw cycles for your study design.
- Review the acceleration factor, accelerated test duration, and estimated shelf life.
- Use the real-time and accelerated pull point counts, along with total samples and tests, to plan lab capacity and study duration.
How the result changes with Accelerated temp (°C)
| Accelerated temp (°C) | Acceleration factor (×) | Accelerated test duration (months) |
|---|---|---|
| 33 | 1.74 | 13.8 |
| 41 | 3.03 | 7.9 |
| 50 | 5.66 | 4.2 |
| 57 | 9.19 | 2.6 |
What each input means
- Target shelf life (months)
- Desired product shelf life in months. Typical: 12-36 months for cosmetics.
- Accelerated temp (°C)
- Temperature for accelerated stability testing. Standard: 40°C per ICH guidelines.
- Storage temp (°C)
- Normal storage/shelf temperature. Standard: 25°C (room temperature).
- Q10 factor
- Rate acceleration per 10°C increase. Typical: 2 for most cosmetics, 3-4 for sensitive formulas.
- Samples per pull point
- Number of samples tested at each time point (triplicates recommended).
- Tests per sample
- Number of tests per sample: pH, viscosity, appearance, color, odor, microbial, etc.
- Freeze-thaw cycles
- Number of freeze-thaw cycles (-10°C to 45°C). Standard: 5 cycles.
What each result means
- Acceleration factor (×)
- How many times faster aging occurs at accelerated temperature vs storage temperature.
- Accelerated test duration (months)
- How long to run the accelerated test to simulate your target shelf life.
- Estimated shelf life (months)
- Shelf life estimate if accelerated testing passes at the specified duration.
- Real-time pull points
- Number of testing time points for the real-time stability study.
- Accelerated pull points
- Number of testing time points for the accelerated study.
- Storage conditions
- Number of different storage conditions (real-time + accelerated + freeze-thaw).
- Total pull points
- Total number of pull/testing events across all conditions.
- Total samples needed
- Total individual samples needed for the entire study.
- Total tests to perform
- Total number of individual tests across all samples and time points.
- Study duration (months)
- Total calendar time for the complete stability study (real-time leg).
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersTarget shelf life (months) = 24, Accelerated temp (°C) = 40, Storage temp (°C) = 25, Q10 factor = 2 = 7 input(s) provided
- Calculate Acceleration factorAcceleration factor = pow(q10Factor, tempDiffOver10)2.83 = 2.83
- Calculate Accelerated test durationAccelerated test duration = targetShelfLifeMonths / accelerationFactor8.5 = 8.5
- Calculate Estimated shelf lifeEstimated shelf life = accelDurationMonths * accelerationFactor24 = 24
- Calculate Real-time pull pointsReal-time pull points9 = 9
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
How does raising Accelerated Temperature shorten the hot-chamber study length?
A higher accelerated temperature increases the exponent in the Q10 formula, raising Acceleration Factor (lines 31-32). Accelerated Test Duration divides target shelf life by that factor (line 35), so a stronger acceleration lets you reach the same simulated age in fewer calendar months at the elevated temperature.
Why do Samples Per Pull and Tests Per Sample not change Acceleration Factor?
Acceleration Factor depends only on accelerated temperature, storage temperature, and the Q10 input (lines 31-32). Samples and tests enter later when Total Samples and Total Tests multiply pull counts by your per-pull sample count and per-sample test count (lines 57-58). They scale lab workload without altering the thermodynamic acceleration math.
How are Real-Time Pull Points chosen for a 24-month shelf life?
The engine filters a fixed schedule of zero, one, two, three, six, nine, twelve, eighteen, twenty-four, thirty-six, and forty-eight months down to entries at or below target shelf life (lines 38-39). If the exact target month is missing from that list, it is appended before the count is returned (lines 40-43).
When does the freeze-thaw leg add pulls and storage conditions?
When Freeze-Thaw Cycles is greater than zero, Storage Conditions adds one leg and Total Pulls includes two freeze-thaw pull events — before and after cycling (lines 53-56). Setting cycles to zero removes that leg entirely while real-time and accelerated arms still run.
Does raising Freeze-Thaw Cycles from, say, 3 to 10 add more pull points or samples?
No — only whether the value is zero or greater than zero matters to the schedule. Any nonzero cycle count adds the same one storage condition and the same two freeze-thaw pulls (before and after cycling); the specific number of cycles you enter beyond that doesn't change Total Pulls, Total Samples, or any other output.
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