Understanding Estimation Accuracy
How we calculate. Accuracy % = (1 − absolute error ÷ actual) × 100 (can be negative if error > actual). See our methodology and accuracy policy .
Real-world scenario: A typical Estimation Accuracy case uses actual 120 and estimate 100. Enter the same figures below to reproduce the worked path.
What is Estimation Accuracy?
A simple forecasting skill metric for teams. Magnitude of Relative Error (MRE) is |A−E|/A; accuracy here is 1 − MRE as a percent.
- Same units for actual and estimate
- 100% = perfect
- Negative means error exceeded the actual
The Formula
Worked Example
Common Use Cases
- Retro metrics: estimate skill
- Vendor scorecards: bid accuracy
- Coaching: improve planning poker
Pro Tips
- Track by work type
- Prefer rolling averages
- Don’t punish learning estimates unfairly
| Scenario | When to use |
|---|---|
| Percent of a number | Finding a part of a whole (tax, tip, score) |
| Percent change | Comparing old vs new values |
Limitations: Estimation Accuracy results are educational software estimation aids—not bids, contracts, or performance scores. Calibrate models to your organization’s history.
Common mistakes
- Swapping part and whole: The denominator must be the full total, not a subset.
- Rounding too early: Carry extra decimal places through multi-step work before rounding the final percent.
- Mixing percent and decimal forms: Enter rates in the format the calculator labels expect.
The worked example for estimation accuracy was verified with the calculator form on this page—enter the same values to confirm the result.
When to use this calculator
- Use this page when your wording matches estimation accuracy and the form labels on screen.
- Use percent of a number for “what is X% of Y?” problems.
- Use number is what percent when you know part and whole and need the percent.
Still unsure about estimation accuracy? Start with the quick answer above, then open the linked calculator that matches your wording.
❓ Frequently Asked Questions
How do I use this estimation accuracy calculator?
For estimation accuracy, enter the values labeled on the form, then press Calculate. Compare the result to the worked example on this page.
What formula does this page use?
See the quick answer and formula box above for estimation accuracy—the same percentage calculator expression is applied to your inputs.
What if my result looks wrong?
When checking estimation accuracy, re-check part vs whole (or rate vs base), rounding, and whether percents were entered as 25 rather than 0.25 when the form expects percents.
Authoritative References
For estimation and quality models, consult:
- COCOMO — Constructive Cost Model overview
- IFPUG — function point standards
- SEI / Carnegie Mellon — software engineering practice