transform(), pipe() & coerce in Zod
From the Zod cheat sheet · Refinements & Transforms · verified Jul 2026
transform(), pipe() & coerce
Convert and transform data during validation
typescript
// Transform output
z.string().transform((val) => val.toUpperCase());
// Chain with pipe
z.string()
.transform((val) => parseInt(val))
.pipe(z.number().int().positive());
// Coerce input to type
z.coerce.number().parse("42"); // 42
z.coerce.date().parse("2024-01-01");💡 z.coerce is a shortcut for the most common preprocess pattern — type coercion
⚡ Use coerce for query params and form data where everything starts as strings
📌 .pipe() chains a transform into another schema for additional validation
🟢 Input and output types differ when transforms change the type — use z.input/z.output
transformcoercepipe