Formula
Base gallons = gallons + extra quarts ÷ 4. Exact US cups = base gallons × 16. US quarts = base gallons × 4. US pints = base gallons × 8. US fluid ounces = base gallons × 128. Litres ≈ base gallons × 3.785411784. Planning cups = exact cups × (1 + allowance percent ÷ 100).
