Thinking Like an Engineer
Tolerance & Precision
12 min · 2 worked examples · 3 questionsFree
Nothing is ever exactly its stated value. Designing for that is the job.
After this lesson you can
- Turn a percentage tolerance into a real range
- Tell accuracy from precision
- Design so that tolerance stops mattering
Every value is a range
A resistor marked 220 Ω is not 220 Ω. It is somewhere near 220 Ω, and the tolerance tells you how near. At 5% tolerance it lies between 209 Ω and 231 Ω. At 1% it lies between 217.8 Ω and 222.2 Ω.
This is not a defect. Manufacturing to tighter tolerance costs more, so components are made to the loosest tolerance that still works, and the tolerance is stated honestly so you can design around it. Assuming a component is exactly its nominal value is the mistake.
In the full lesson
- Every value is a range
- Accuracy is not precision
- Tolerances stack
- Design so tolerance does not matter
Free with an account. Read it, work the examples, answer the questions, then build it in the simulator.