Free Boundary Value Analysis Calculator
Off-by-one bugs live at the edges. Enter a field's valid range and precision, and get its equivalence partitions plus the exact boundary values to test - 2-point or 3-point BVA, with expected accept/reject results.
Input fields
One row per numeric field: its valid range and precision (the smallest increment the field accepts).
Boundary Value Analysis
Technique: 2-point BVA
Age (valid: 18 to 65)
| Equivalence partition | Range | Expected |
|---|---|---|
| Invalid (below) | < 18 | Reject |
| Valid | 18 to 65 | Accept |
| Invalid (above) | > 65 | Reject |
| Test value | Boundary | Expected |
|---|---|---|
| 17 | Just below minimum | Reject |
| 18 | Minimum (boundary) | Accept |
| 42 | Middle of valid partition | Accept |
| 65 | Maximum (boundary) | Accept |
| 66 | Just above maximum | Reject |
How it works
Describe the fields
One row per numeric input: its name, minimum, maximum, and precision (the smallest increment it accepts - 1 for whole numbers, 0.01 for money).
Pick the technique
2-point BVA tests each boundary and just outside it; 3-point adds the just-inside values, which catches a subtler class of comparison bugs.
Test the generated values
You get each field's partitions and a ready-to-run table of test values with expected accept/reject outcomes. Export CSV, Markdown, or print it.
Boundary value analysis and equivalence partitioning, briefly
Equivalence partitioning splits an input's possible values into groups the system should treat identically: for an age field accepting 18 to 65, the partitions are "below 18" (reject), "18 to 65" (accept), and "above 65" (reject). One test per partition covers the behavior - testing 30, 40, and 50 separately adds nothing.
Boundary value analysis sharpens this: implementations fail at partition edges, because that is where a developer wrote >= instead of >, or an off-by-one in validation. So instead of any value per partition, you test exactly at and around the boundaries: 17, 18, 65, 66 - plus 19 and 64 in the 3-point variant.
Both techniques are core ISTQB Foundation material, and together they turn "what values should I test?" from guesswork into a five-minute calculation. This calculator does the arithmetic, including decimal precision, so the just-outside value of a 0.01-precision price field is 99.99, not 99.
Frequently asked questions
Is this BVA calculator free?
Yes - free, no signup, no limits. It runs entirely in your browser. It is built by the team behind BesTest, a test management app for Jira.
What is the difference between 2-point and 3-point BVA?
2-point BVA tests each boundary value and the value just outside it (for a 18-65 range: 17, 18, 65, 66). 3-point BVA adds the values just inside each boundary (19 and 64), which additionally catches faults where the boundary check is inverted rather than shifted. ISTQB syllabi cover both.
Why does the precision (step) matter?
The "just outside" value depends on the smallest increment the field accepts. For a whole-number age field, just below 18 is 17. For a price field with 0.01 precision and a 100.00 maximum, just above is 100.01 - not 101. The calculator handles decimal precision for exactly this reason.
Does BVA replace testing values in the middle of the range?
No - it complements it. The calculator includes one representative mid-range value per field (the equivalence partitioning part) alongside the boundary values. What BVA replaces is the habit of testing many arbitrary mid-range values, which all belong to the same partition and find the same bugs.
Five test values calculated. Now make them a test case that survives.
Paste these values into a BesTest test case in Jira and they become executable, reviewable, and traceable to the requirement that defined the range - so when the range changes next quarter, you know exactly which tests to update.
Free for teams up to 10 users. All features included.
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