Similar to most fixed income securities in Australia, Treasury Bonds are quoted and traded on a yield to maturity basis rather than on a price basis. This means the price is calculated after agreeing on the yield, by inputting the yield into the appropriate pricing formula.
The price per \( $100 \) face value is calculated using the following pricing formulae:
Basic formula: 
$$\Large P = v^\frac{f}{d}\left(g \left( 1 + \require{enclose}a_{\enclose{actuarial}{n}} \right) + 100 v^{n} \right)$$

$$\Large (1)$$ 
Ex interest bonds: 
$$\Large P = v^\frac{f}{d}\left(g \require{enclose}a_{\enclose{actuarial}{n}} + 100 v^{n} \right)$$

$$\Large (2)$$ 
Nearmaturing bonds (between the record date for the second last coupon and the record date for the final coupon): 
$$\Large P = \frac{100 + g}{1 + \left(\frac{f}{365}\right) i}$$

$$\Large (3)$$ 
Nearmaturing bonds (between the record date for the final coupon and maturity of the bond): 
$$\Large P = \frac{100}{1 + \left(\frac{f}{365}\right) i}$$

$$\Large (4)$$ 
In these formulae:
$$\large P=$$

the price per $100 face value. \( P \) is rounded to three decimal places in formulae \( (1) \) and \( (2) \), and unrounded in formulae \( (3) \) and \( (4) \). 
$$\large v=$$

\( \LARGE \frac{1}{1 + i} \)

$$\large i=$$

the annual percentage yield to maturity divided by 200 in formulae \( (1) \) and \( (2) \), or the annual percentage yield to maturity divided by \( 100 \) in formula \( (3) \) and \( (4) \). 
$$\large f=$$

the number of days from the date of settlement to the next interest payment date in formulae \( (1) \) and \( (2) \) or to the maturity date in formula \( (3) \). In formula \( (3) \), if the maturity date falls on a nonbusiness day, the next good business day (as defined in the Information Memorandum) is used in the calculation of \( f \). 
$$\large d=$$

the number of days in the half year ending on the next interest payment date 
$$\large g=$$

the halfyearly rate of coupon payment per \( $100 \) face value 
$$\large n=$$

the term in half years from the next interestpayment date to maturity 
$$\large \require{enclose}a_{\enclose{actuarial}{n}}=$$ 
\( \large v + v^2 + ... + v^n = \frac{1  v^n}{i} .\ \mathrm{Except \, if\ \,} i = 0 \ \mathrm{\,then\,}\ \require{enclose}a_{\enclose{actuarial}{n}} = n \) 
Settlement amounts are rounded to the nearest cent (0.5 cent being rounded up).
Worked Example
As an example of the working of the basic formula, the price of the \( 2.75 \% \) 21 November 2028 Treasury Bond, assuming a yield to maturity of \( 2.8300 \% \) per annum and settlement date of 27 October 2017, is calculated to be \( $100.431 \).
In this example, \( i = 0.014150 \) (i.e. \( 2.830 \) divided by \( 200 \)), \( f = 25 \), \( d = 184 \), \( g = 1.375 \) (i.e. half of \( 2.75 \)) and \( n = 22\).
If the trade was for Treasury Bonds with a face value of \( \normalsize $50,000,000 \) the settlement amount would be \( $50,215,500.00 \).
ExInterest Treasury Bonds
The exinterest period for Treasury Bonds is seven calendar days. With exinterest Treasury Bonds the next coupon payment is not payable to a purchaser of the bonds. In this case, calculation of an exinterest price is effected by the removal of the '\( 1 \)' from the term:
\( \large 1+\require{enclose}a_{\enclose{actuarial}{n}}\)
in formula \( (1) \), thereby adjusting for the fact that the purchaser will not receive a coupon payment at the next interest payment date.
NearMaturing Treasury Bonds
When a Treasury Bond goes exinterest for the second last time it is treated as a special case. In this case formula \( (3) \) applies up until the record date for the final interest payment and formula \( (4) \) applies from the time the bond goes exinterest for the final time. There may be a slight discontinuity in the progress of the price of the bond around the time the bond goes exinterest for the second last time but market participants can, if they wish, allow for this in their trading.
Where the maturity date coincides with a weekend or public holiday, the commonly accepted practice is to price nearmaturing Treasury Bonds according to the actual date the principal and final interest are paid (and not the nominal maturity date).