Calculated Result
Interpretation
Acceptance Check
Calculator Inputs
Plotly Graph
Calculation History
| Scenario | Nominal | Limits | Expanded Uncertainty | TUR | Target Check | Acceptance |
|---|
Formula Used
This page computes the ratio from tolerance span and expanded uncertainty. If you enter standard uncertainty, the page first converts it to expanded uncertainty using the chosen coverage factor.
The calculator also checks the observed value against the stated limits and an optional guard band. That gives you both a ratio result and a practical decision view.
How to Use This Calculator
- Enter a scenario name, nominal value, and the unit you want to track.
- Choose either symmetric ± tolerance or direct lower and upper limits.
- Enter expanded uncertainty directly, or switch to standard uncertainty and supply the coverage factor.
- Optionally add an observed value and a guard band for a stricter acceptance decision.
- Set your target ratio, then click Calculate TUR to see the result above the form.
- Review the graph and history table, then export the records as CSV or PDF if needed.
Example Data Table
| Scenario | Nominal | Unit | ± Tolerance | Expanded Uncertainty | TUR |
|---|---|---|---|---|---|
| Voltage Check | 10.000 | V | 0.100 | 0.0250 | 4.00:1 |
| Pressure Check | 50.000 | psi | 0.200 | 0.0400 | 5.00:1 |
| Mass Check | 100.000 | g | 0.500 | 0.1250 | 4.00:1 |
| Length Check | 25.000 | mm | 0.050 | 0.0200 | 2.50:1 |
FAQs
What is a test uncertainty ratio?
It compares available tolerance to measurement uncertainty. A larger ratio generally means the calibration process is better separated from the allowed tolerance band.
Which formula does this calculator use?
It calculates tolerance span, expanded uncertainty, and TUR. For symmetric ± limits, the result simplifies to one-sided tolerance divided by expanded uncertainty.
Why does the page ask for a target TUR?
A target ratio gives you a quick screening benchmark. Different procedures, contracts, and risk rules may require different minimum ratios.
What is the difference between standard and expanded uncertainty?
Standard uncertainty is the base uncertainty estimate. Expanded uncertainty equals standard uncertainty multiplied by a coverage factor, often written as k.
Should all values use the same unit?
Yes. Tolerances, readings, and uncertainty must use the same unit so the ratio remains meaningful and the comparisons stay valid.
Can I use lower and upper limits instead of ± tolerance?
Yes. Choose the direct limits mode when your specification is asymmetric or already defined by explicit lower and upper values.
What does the guard band field do?
It tightens the acceptance window inside the stated limits. This helps you evaluate a more conservative accept or reject decision.
Why export CSV or PDF?
Exports help you document calculations, compare scenarios later, and share evidence with reviewers, auditors, customers, or teammates.