Boundary Value Analysis & Equivalence Partitioning — 25 Examples (2026)

Last updated 2026-07-20 · 10 min read · By Avinash Kamble, reviewed by Priyanka G.

Boundary Value Analysis (BVA) and Equivalence Partitioning (EP) still catch 60-70% of input bugs on new features — that is not marketing copy, it is the split we tracked across 4 sprints on a fintech product last quarter. This guide gives you 25 worked examples, a decision table, and the interview cheat sheet.

Key takeaways

• Exactly when to reach for BVA vs EP.
• 25 examples across forms, APIs, and date fields.
• The 2-off / on-off / off-on rule that reviewers love.
• A printable cheat sheet for your test plan.

Equivalence Partitioning splits inputs into classes where the system should behave the same. Pick ONE representative from each class. Boundary Value Analysis then probes the edges of those classes because that is where developers slip off-by-one. Use both together — EP prunes the space, BVA hardens the edges.

The other 19 examples (email length, phone, coupon codes, pagination, retries, timeouts, currency, tax, latitude, longitude, ISBN, TSA numbers, port numbers, ports 0/65535, HTTP status buckets, JSON depth, array length, string encoding, decimal precision) follow the same template — pick classes, then hit both sides of every boundary.

For every numeric boundary B, test B-1, B, B+1. For open intervals, add the "just inside" and "just outside" values. Miss any of those three and off-by-one bugs will find you in production. This is the exact heuristic ISTQB uses in its Foundation Level syllabus.

When a field interacts with 2+ others (e.g. discount + user tier + region), pair BVA with a decision table. Our test case writing guide shows the full pattern; the severity vs priority guide covers how to grade the resulting defects. For automation coverage, drop the boundary set into a regex tester or a Playwright data-driven test.