Why are Styku measurements different from my tape measure measurements?
Why are Styku measurements different from my tape measure measurements?
All methods of measuring have error. Styku's circumferences are precise and reliable.
The error of a measurement is determined by comparing it to a "ground truth" value with a lower margin of error than the measurement being assessed. For Styku circumference measurements, the expected margin of error in the torso is ±0.5% — about half of one percent of the measurement value.
In practical terms: if Styku measures a waist at 40 inches, repeated scans of the same person around the same time will be within 0.2 inches (0.5% of 40) of the original value. The precision (repeatability) of Styku's measurement is within about 0.2 inches.
Why doesn't Styku match my tape measurements?
The short answer is that Styku measures differently than you do, and your manual measurement has a larger margin of error than Styku's.
Example: ask three people to measure one person's abdominal waist. You'll get three different values, because the exact landmark wasn't defined. Even if a standard measurement location is set, each person will hold the tape differently — tighter, looser, higher, lower.
The average error for tape measurements is greater than Styku's margin of error. In Styku's testing, the difference between measurements taken by different people of the same subject can be greater than 1 inch.
As a result, Styku's measurement and a manual tape measurement won't match exactly every time — but that's fine.
What matters for tracking change is repeatability
You can only track change in a measurement if the amount of change is greater than the margin of error. If the error margin is low, you can be confident the change is real and not just noise.
Styku's measurement precision is better than a tape measure's, so Styku is a better tool for tracking change. Even if the absolute waist value differs from what you'd measure manually, what matters more is that the value is consistent across scans — so when it goes down by 3 inches, you know that's a real change in the client's body.
Applies to: All Styku configurations.
Related Resources
- How accurate are Styku's circumference and length measurements?
- What is a tape measure and how should it be used for body measurements?
- What accuracy, precision, and reliability mean for body composition tools — and why all three matter for tracking progress
- What does Styku measure, and what data do clients receive after a scan?