Percentage Change Calculator

Percentage Change – Quick Cheat Sheet

• Δ (absolute change) = new − old
• % change = (Δ / |old|) × 100 (base is the old value’s magnitude)
• Sign meaning: positive = increase, negative = decrease, zero = no change
• Edge case: if old = 0 and new ≠ 0, percent change is undefined (division by zero). If old = 0 and new = 0, result is 0%.
• Tip: For “% difference” between two values (orderless), use |new − old| / ((|new| + |old|)/2).