The notional amount (or notional principal amount or notional value) on a financial instrument is the nominal or face amount that is used to calculate payments made on that instrument. This amount generally does not change and is thus referred to as notional. Explanation Contrast a bond with an interest rate swap: In a bond, the buyer pays the principal amount at issue (start), then receives coupons (computed off this principal) over the life of the bond, then receives the principal back at maturity (end). In a swap, no principal changes hands at inception (start) or expiry (end), and in the meantime, interest payments are computed based on a notional amount, which acts as if it were the principal amount of a bond, hence the term notional principal amount, abbreviated to notional. In simple terms, the notional principal amount is essentially how much of an asset or bonds a person owns. For example, if a premium bond were bought for £1, then the notional principal amount would be the face value amount of the premium bond that £1 was able to purchase. Hence, the notional principal amount is the quantity of the assets and bonds. Examples Interest rate swaps In the context of an interest rate swap, the notional principal amount is the specified amount on which the exchanged interest payments are based; this could be 8000 US dollars, or 2.7 million pounds sterling, or any other combination of a number and a currency. Each period's rates are multiplied by the notional principal amount to determine the height and currency of each counter-party's payment. A notional principal amount is an amount used as a reference to calculate the amount of interest due on an 'interest only class' which is not entitled to any principal. Total return swaps In a typical total return swap, one party pays a fixed or floating rate multiplied by a notional principal amount plus the depreciation, if any, in a notional amount of property, in exchange for payments by the other party of the appreciation, if any, on the same notional amount of property. For example, assume the underlying property is the S&P 500 stock index" A would pay B the London Inter-Bank Offered Rate, multiplied by a $100 notional amount plus depreciation, if any, on a $100 notional investment in the S&P 500 index. B would pay A the appreciation, if any, in the same