Feet to Inches Calculator

Feet and inches are both part of the US customary and imperial measurement systems, but many measurement tools, formulas, and databases require a single unit rather than a mixed format. Converting from feet to inches is needed when entering height into medical or sports databases (which often require total inches), calculating fabric or lumber lengths where fractions of a foot must be expressed precisely, computing BMI from height in inches, or verifying room dimensions against blueprints that use inch notation. This calculator multiplies any foot value — including decimals like 5.75 feet — by exactly 12 to produce the equivalent inch count, rounded to four decimal places for precision.

Inches = Feet × 12. The relationship is exact and defined: one foot is officially defined as 12 inches by the US National Institute of Standards and Technology. Decimal foot inputs are handled by simple multiplication — 5.75 feet × 12 = 69 inches exactly (5 feet 9 inches). The result is displayed to four decimal places to accommodate irrational or repeating decimal inputs like 1/3 foot = 4.0000 inches (which is exact) vs. 1/7 foot ≈ 1.7143 inches.