RUŌOD Lab

Level 5 · Perfume Mathematics and Formula Design

Absolute and Relative Percentage: Study Guide

Read our guide to absolute and relative percentage, then calculate all three shares for a formula and decide which one answers each practical question.

Intermediate 15 min study By the RUŌOD Lab team Updated

In short

A diluted line has three different percentages, and confusing them is a classic source of errors. The reference guide defines them and explains their uses. This study guide has you calculate all three for one formula, then match each to the question it answers.

What you will learn

  • Calculate formula, absolute and relative shares
  • Choose the right share for a given question

Before this lesson: Solvent in a Formula: What It Does to Your Numbers

What to look for as you read

  • Which percentage changes when you add solvent, and which stays the same.
  • Which percentage a restriction check actually depends on, and why finished-product strength must come into it.

Practical exercise: Three shares, four questions

About 25 minutes · You will have: a table of the three shares for one formula, and four questions answered with the right one

Take this formula: P 4.00 g neat, Q 4.00 g at 10%, R 2.00 g at 1%.

  1. Calculate pure active for each. P 4.00, Q 0.40, R 0.02; total 4.42 g.
  2. Calculate formula, absolute and relative share for each. For Q: 40%, 4%, 9.05%.
  3. Which share answers each? (a) What do I weigh? (b) What is this formula made of, as a smell? (c) How much pure Q is in each gram of this concentrate? (d) If the concentrate is 20% of the finished product, how much pure Q is in the product?
  4. Work (d) for Q. Absolute 4% × 20% = 0.8% of the finished product.

You have done this well if you chose formula, relative, absolute and absolute for (a) to (d), with the numbers tying out.

Knowledge check

1. Which share describes a line's contribution to the smell of the composition?
Show the answer

Relative share, since it leaves solvent out. Relative share is pure active over total pure active, so solvent does not affect it.

2. What do you need for weighing a batch?
Show the answer

Formula share. Formula share is what goes on the scale.

3. If you add solvent to a concentrate, which share does not change?
Show the answer

Relative share. Adding solvent changes the total weight, but not the ratio of pure materials to one another.

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.