How to Use Litmus Paper for pH Testing
By Apothecary Products | Published: 2026-10-29
Category: How-to Guides
Learn how to use litmus paper to test the acid-base balance of solutions. This guide covers the simple steps, common mistakes, and when to use this classic pH test strip.
Quick answer
Dip a strip of litmus paper into your solution for one second, then compare the color change to a pH chart. Red indicates acid, blue indicates base.
What litmus paper can and cannot tell you
Litmus paper gives a simple yes/no answer: is the solution acidic or basic? It does not measure a specific pH number. For that, you need a wider-range pH test strip or a digital meter.
The paper comes in two colors: red (turns blue in base) and blue (turns red in acid). A 100-count pack from Apothecary Products gives you plenty of strips for classroom, lab, or home use.
How to use litmus paper in 4 steps
- Prepare your sample: Make sure the solution is at room temperature and well-mixed. Use a clean glass or plastic container to avoid contamination. Cold or hot solutions can slow or skew the color change. Stick to room temperature.
- Dip the strip: Take one strip of litmus paper and dip it into the solution for about one second. Do not stir or leave it in longer. A quick dip is enough. Prolonged soaking can cause the strip to disintegrate or give a false reading.
- Remove and observe: Lift the strip out and hold it horizontally for 10–15 seconds. Watch for a color change: blue paper turning red means acid; red paper turning blue means base. If the paper stays its original color, the solution is neutral (neither acidic nor basic).
- Compare and record: Hold the strip next to a white background in good light. Compare the final color to the pH color chart that came with your strips. Note the result. Write down the color and your interpretation immediately—colors can fade as the strip dries.
Product used in this guide
- Litmus Paper: Litmus Paper from Apothecary Products is a 100-count pack of testing strips for checking the acid-base balance of solutions. Made in the USA. A 100-count pack gives you enough strips for repeated testing without running out quickly, making it practical for classroom or home lab use.
Litmus Paper
