The conversion ratio specifies shares per stated principal amount. A USD100 bond and USD25 conversion price show why quantity, conversion value and delta differ.
Conversion ratio
The conversion ratio is the contractual number of underlying shares associated with conversion of a specified amount of a convertible bond. In a straightforward share-settled bond, it tells the holder how many shares that bond delivers on conversion. It is the quantity needed to translate a stock price into conversion value, so getting its denominator wrong can misstate the equity value of an entire position.
The denominator is part of the definition: “shares per bond” is incomplete until the bond's face amount is known. Documents may instead state a conversion rate per specified amount of principal. Cash or mixed settlement can also mean that the quoted share quantity determines a settlement calculation rather than the number of shares actually delivered.
From face amount to shares
For a fixed-ratio contract with face amount N per bond and conversion priceK per share, both in the same currency,
R=KN.
The units are shares per bond. The numerator is face value, not the convertible's current market price. A market quote expressed as a percentage of face must not be substituted for a currency amount per bond.
Consider a fictional USD100-face bond, with a stipulated conversion price of USD25 per share and settlement entirely in shares when conversion is permitted. Its ratio is 100/25=4 shares per bond. If the stock trades at USD30 per share, those shares have a spot value of 4×30=120 USD per bond. This is conversion value, also called parity:
Vconversion=RS.
Here S is the stock's market price in USD per share. USD120 is the value of the conversion shares at that spot, not a calculation of the convertible's market price, profit or optimal conversion decision. If the bond is retained, its coupons and debt claim remain relevant; converting can give up those rights.
Fictional USD100 face per bond divided by USD25 conversion price per share gives four shares per bond. At USD30 per share, conversion value is USD120 per bond.
One stipulated share-settled contract, on a one-bond basis. The ratio fixes the share quantity; the stock price determines its spot value. Eligibility and actual settlement depend on the documents.
Changing the denomination changes the shares-per-bond number even when the conversion price is unchanged:
Fictional denomination
Conversion price
Conversion ratio
Conversion value at USD30/share
USD100 face per bond
USD25/share
4 shares/bond
USD120/bond
USD1,000 face per bond
USD25/share
40 shares/bond
USD1,200/bond
These are stipulated examples, not a universal quotation or denomination convention. To compare two ratios, first put their principal denominators, currencies and underlying share units on the same basis. A cross-currency instrument also requires the contract's currency-conversion provisions; the simple same-currency quotient above is insufficient on its own.
Our Convertible Terminology and Payoff lesson connects the ratio to a simplified maturity payoff and issuer call and investor put rights. The full lesson requires membership; a public preview is available.
A ratio is neither a hedge nor permission to convert
A fixed ratio stays at four shares in the first example when the stock price moves. The convertible's delta, however, measures how its own value responds to a stock-price change, holding the model's other inputs fixed. Expressed in currency per bond against currency per share, delta also has share units. Matching units do not make it equal to the conversion ratio. The ratio is the slope of conversion value; the bond's sensitivity additionally reflects its remaining contractual cashflows, optionality and credit exposure.
The ratio also does not establish that conversion is allowed today. Read the conversion window, any conditional conversion tests, notice requirements and settlement provisions. A stock price above the conversion price does not by itself satisfy all those terms or establish that early conversion is the best choice.
Nor is the initial ratio necessarily permanent. Anti-dilution provisions, contractual resets and certain corporate events can alter the applicable rate or conversion consideration. Apply the document's adjustment rules, effective dates and rounding provisions rather than assuming that every dividend or share-price decline produces an adjustment.
Actual filings illustrate the distinction between a rate and settlement rights. BlackSky's July 2025 Form 8-K, Item 1.01, states a conversion rate per specified principal amount, allows issuer-selected cash, shares or a combination, and describes circumstances that adjust the rate. Complete Solaria's September 2024 Form 8-K, Item 1.01, separately specifies a conversion start date, settlement alternatives and rate adjustments. These are examples of particular issued terms, not general rules for all convertibles.
Sources
De Spiegeleer, J. and Schoutens, W., The Handbook of Convertible Bonds: Pricing, Strategies and Risk Management, first edition, Wiley, 2011, Chapter 1, p. 16 (conversion data) and pp. 21–22 (capital distributions and parity quotation).
