In short
Functional fragrance decisions balance dose, cost and performance within a small budget. A fragrance that seems pricey per kilogram may be cheap in use if it performs at a lower dose, and a higher dose can stop helping, or it may damage the base. So you compare options by what they cost per product, at a measured level of performance. The Lab's guide to fragrance load covers the basic arithmetic.
What you will learn
- Calculate fragrance cost per unit and per use
- Compare options by performance against cost
- Make a dose decision and record its reasoning
Before this lesson: Candles and Air Care Engineering
Cost in use
| Fragrance | Price per kg | Dose | Fragrance per 500 g unit (g) | Cost per unit |
|---|---|---|---|---|
| A | 30 | 0.8% | 4.0 | 0.12 |
| B | 60 | 0.4% | 2.0 | 0.12 |
| C | 90 | 0.2% | 1.0 | 0.09 |
If all three performed equally, C would be cheapest per unit, despite having the highest price per kilogram. But equal performance is an assumption until it is tested. Note also that a lower dose can change other factors, such as allergen declarations, viscosity and supply risk.
Cost per use
Sometimes the right measure is per wash, or per week. A 500 g unit used at 25 g per wash gives 20 washes, so fragrance A costs 0.006 per wash. That sounds tiny, but in a high-volume product, small differences matter. For a small maker, the fragrance cost may not matter at all compared with the packaging, as your capstone costing showed. Calculate before you assume.
Measuring response to dose
Strength doesn't rise in step with dose. Often there's a range where increasing the dose gives a clear gain, then a flatter region. Find it in your own base.
- Choose your stage, because different stages give different answers: bottle, in use or on the substrate.
- Set three or four doses, spaced widely enough to detect, within applicable limits.
- Code the samples, and have assessors rate strength against an anchor.
- Plot rating against dose. Include cost as a second line.
- Look for the point where more cost buys little more strength.
Other things that move with dose
| Effect | What to check |
|---|---|
| Regulatory | Limits for each restricted material in that category; allergen labeling |
| Base stability | Viscosity, clarity, separation over time |
| Performance of the base | Foam, cleaning, burn |
| Consumer comfort | Too strong in a closed room, or in use |
| Safety | The assessor's view of the actual dose and exposure |
| Flammability | Flash point of the mixture, particularly for home fragrance |
Reformulating to a cost
Functional work often goes through several rounds of cost reduction. Use the same logic as in reducing cost, except that you are testing in the base, and at the stage that matters to the user. In a fabric softener, a saving on a top note that nobody smells on dry fabric might be fine, while a saving on the fabric-substantive line might be costly. So tie each saving to a stage.
Recording your decision
Invented example: Chose fragrance B at 0.5%. Dose chosen because rated strength in use stopped rising above about 0.5% in our test with four assessors. Cost is 0.15 per unit, under the 0.20 target. No limit was exceeded by our self-check on this date. Viscosity remained within our provisional range after four weeks in our trial. Not yet tested: long-term stability, safety assessment.
Practical exercise: A dose and cost matrix
- Choose a product type and a target cost, stated as a cost per unit.
- Take two fragrances you've made, and cost them from real quotes.
- Calculate cost per unit at three doses, and per use if that applies.
- Check each dose against limits for one key material, with date and source.
- Test strength at each dose, using coded samples, in a simple base. These samples aren't for use on skin.
- Plot the result, and write a decision record with the reasons and what's still untested.
You have done this well if you compare options at a measured performance level, the arithmetic can be rechecked and your decision states what wasn't tested.
Common mistakes
- Comparing only price per kilogram. Compare in-use cost.
- Assuming equal performance. Test.
- Ignoring the stage. A saving may affect the one moment that matters.
Knowledge check
Written and reviewed by the RUŌOD Lab team. This is general education, not legal, regulatory, medical or safety advice. Example dilutions and exercises are for learning, are not validated products, and have not been safety-assessed. Completing a lesson confers no qualification. How we check these lessons.