In short
A formula tool is valuable because it holds records and does the arithmetic reliably, but it can only be as right as what you enter. Use one as a check on your own understanding rather than as a replacement for it. This lesson describes how, using the RUŌOD Lab app as an example, and closes Level 5. A spreadsheet can do the same job, and none of this requires the app.
What you will learn
- Use a formula tool as a check, not a substitute
- Interpret formula, absolute and relative figures in an app
- Complete the Level 5 project
Before this lesson: Reproducibility Test: Weigh It Twice
What the app holds and calculates
RUŌOD Lab is an Android application. A formula in it is a list of materials, each with a weight and a dilution, and one calculation engine derives the rest:
| In this course | What it is |
|---|---|
| Pure active | Weight × dilution for each line |
| Carried solvent | The rest of that line's weight |
| Formula share | Line weight ÷ total weight |
| Absolute share | Pure active ÷ total weight |
| Relative share | Pure active ÷ total pure active |
It can also scale a formula to a total weight or by a factor, change its concentration by adjusting free solvent, work out production targets, and switch a line's dilution using the three methods you practiced. Formulas carry a version number, and Duplicate makes a marked new copy. Other features, such as reports beyond the first and some exports, belong to the Premium plan, as the pricing section sets out.
What it does not do
- It does not compose. There is no AI and nothing that proposes materials.
- It does not supply limits. The app ships no IFRA data. It flags a line whose relative percentage exceeds a limit that you recorded on the material, and it does not add up constituents of natural materials. A flag, or no flag, is not a compliance decision.
- It does not evaluate. The smell remains your job.
- It does not nest formulas. A premix is entered as a material.
Testing any tool
The guide on testing perfume software calculations describes a fuller method. A quick version is to enter a formula whose answers you have worked by hand, including at least one diluted line and a total you can check. If anything disagrees, stop and find out why. Often it is your input. Sometimes it is a definition: one tool's "percent" may not be yours.
A sensible workflow
- Compose and weigh, recording actual weights.
- Enter the formula with its true dilutions.
- Compare the computed pure active and shares with what you expected.
- Use the tool to scale, and to generate a batch sheet you check against your scale's limits. The tool does not know your practical minimum.
- Duplicate before changing anything, and describe each change in the notes.
Practical exercise: The Level 5 project: one formula, checked twice
This is the Level 5 project. Use a formula with at least six lines, at least two of them diluted. A spreadsheet, the formula spreadsheet guide or the app can serve as your second calculation.
- By hand, calculate pure active, the three shares and the active strength of the concentrate.
- Normalize it to 1,000 parts of pure active.
- Scale it to a batch you can weigh, and write a batch sheet, with stocks.
- Calculate the concentrate and alcohol for 30 g at a stated active strength. State your convention.
- Enter the formula in your tool, and compare each figure with your own.
- Make the batch, and refer to your result from the reproducibility test.
Assess yourself against these criteria: hand and tool figures agree, or you explained each difference; every weight is above your practical minimum; every total ties out; and someone else could remake the batch from your sheet. Passing this says that your arithmetic and records are sound. It says nothing about whether the formula is safe or good.
Common mistakes
- Trusting output you cannot estimate. Keep doing rough estimates in your head.
- Treating a compliance flag as a verdict. It only reflects what you entered.
- Entering a dilution as neat for convenience. Every later figure inherits the error.
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.