RUŌOD Lab

Level 5 · Perfume Mathematics and Formula Design

Percent and Parts: Study Guide and Drill

Read our parts-per-thousand guide, then practice moving a formula between grams, percent and parts until you can spot a wrong total on sight.

Intermediate 15 min study By the RUŌOD Lab team Updated

In short

A formula can be written in grams, percent or parts per 1,000, and all three say the same thing. The reference guide explains why perfumers like parts per 1,000. This study guide drills the conversion until it becomes automatic, as every calculation in this level uses it.

What you will learn

  • Convert a formula between grams, percent and parts per 1,000
  • Check a converted formula against its total

Before this lesson: Weight, Not Volume: Study Guide and Density Check

The conversions in one place

  • Grams to percent: line ÷ total × 100.
  • Percent to parts per 1,000: multiply by 10.
  • Parts per 1,000 to grams for a batch: parts × batch weight ÷ 1,000.

Practical exercise: Convert three formulas

About 25 minutes · You will have: three worked conversions, each checked against its total

  1. Convert these bench weights to percent and parts per 1,000: A 6.40 g, B 2.00 g, C 1.20 g, D 0.40 g. Check: total 10.00 g, giving 64 / 20 / 12 / 4%, and 640 / 200 / 120 / 40 parts.
  2. Copy the first ten lines of Mandarin Tiles. Treat them as a complete small formula, and rescale their shares so they total 100%.
  3. Write a four-line formula of your own, in parts per 1,000, then calculate the grams for a 7.5 g batch.

You have done this well if every result ties back to its total, and you checked before moving on.

Knowledge check

1. A material is 12.5 parts per 1,000. What percent is that?
Show the answer

1.25%. Divide parts per 1,000 by 10 to get percent: 12.5 ÷ 10 = 1.25%.

2. Why write a formula in parts per 1,000?
Show the answer

Small lines stay readable, and it does not depend on batch size. It is a size-independent way to write a formula, and small lines do not turn into long decimals.

3. Your percentages total 99.4. What should you do?
Show the answer

Find whether it is rounding or a mistake before going on. Rounding can explain a small gap, but so can an error. Check it, then decide where any residual goes.

Further reading and materials

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.