About this tool
Defects cluster at the edges of input ranges: a check written as “<” instead of “<=”, a length limit that counts bytes instead of characters, a date filter that drops the last day. Boundary value analysis targets exactly those places. Enter the valid range and this calculator lists the values on, just inside and just outside each boundary, marks which ones the system should accept or reject, and derives the equivalence partitions with a representative value for each. It supports decimal precision (for example 0.01 for currency), string lengths that cannot go below zero, and calendar dates that step correctly across month ends and leap days. Switch between the ISTQB 2-value and 3-value variants and the classic 7-value set that adds a nominal mid-range value.
How to use it
- Pick the input type: number, string length or date range.
- Enter the inclusive minimum and maximum, and for numbers the step that matches the field’s precision.
- Choose the BVA variant. The table shows each value with its boundary label and expected result.
- Review the equivalence partitions, then copy or download everything as CSV for your test case document.
Boundary Value Calculator FAQ
What is the difference between 2-value and 3-value boundary value analysis?
Two-value BVA tests each boundary and its nearest neighbour in the adjacent partition (for 1-100: 0, 1, 100, 101). Three-value BVA adds the neighbour on the inside too (0, 1, 2, 99, 100, 101), which also catches a boundary that was moved inward by one step.
How do I choose the step for decimal fields?
Use the smallest increment the field accepts. A price stored with two decimals has a step of 0.01, so for 0.01 to 999.99 the values just outside are 0.00 and 1000.00. If the precision is not specified, that is a requirements gap worth raising.
What if the specification says “less than 100” rather than “up to 100”?
The tool treats both ends as inclusive. For an exclusive limit, enter the last valid value instead: “less than 100” for integers means a maximum of 99.