Clean and full price
The clean price is a bond's price without accrued interest, the one quoted on screens; the full (dirty) price adds the interest accrued since the last coupon and is what a buyer actually pays.
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How it is computed here
Our estimate of the clean price comes from discounting the bond's remaining payments with the Treasury's par curve of the day; the full price is that plus the accrued interest on the actual/actual convention. A position is valued at the full price, because that is what its remaining payments are worth. For a TIPS, both are per 100 of inflation-adjusted principal.
Worked example
- UST 4.625% 2036-08-15 on 2 Oct 2026: clean price 95.008 and accrued interest 0.603, per 100.
- Full price = 95.008 + 0.603 = 95.611 per 100: what a buyer pays at settlement.
- On 10,000 of face value the position is worth 9,561.11 USD: our estimate from the Treasury curve, not a dealer quote.
Real Treasuries valued today on the Treasury's par curve: our estimates, not dealer quotes, and no yield here is a return anyone is owed. The demo holds none; signed in with a Treasury of your own, this is worked on yours.
Where it misleads
The full price rises a little each day as interest accrues and drops by the coupon on the day it is paid, so comparing full prices across a coupon date mixes price changes with payments; the clean price is the one to compare over time. Both are our estimates from the Treasury curve, not dealer quotes, and for a TIPS they can differ from market prices by more than a point.
The formula
- Clean price — the price per 100 of face value without accrued interest;
- Accrued interest — the part of the next coupon earned since the last coupon date (see its own lesson);
- Full price — what a buyer pays at settlement per 100 of face value.
A worked example on a real Treasury
The Treasury note UST 4.625% 2036-08-15 on 1 October 2026: clean price 95.305, accrued interest 0.591, full price 95.305 + 0.591 = 95.896 per 100 of face value. On 10,000 of face value a buyer would pay 9,589.61 at settlement, of which 59.07 is the interest the seller earned in the 47 days since 15 August. On 15 February 2027, when the 231.25 coupon is paid, the full price drops by about that coupon and the accrued interest starts again from zero, while the clean price barely moves. Every figure is our estimate from the Treasury curve, not a dealer quote.
What this page does not do
A clean price is a convention, not a different value: the same bond has one value, and the two prices differ only by interest that is paid back. This page does not say whether a price is high or low.
Compared with
- Accrued interest — the part of the next coupon already earned
- Yield to maturity — the rate that reproduces the full price
- Modified duration — how much the price moves for a one-point change in yield
Questions people ask
Which price does Sphinx Risk use to value my position?
The full price, since it is what the bond's remaining payments, accrued coupon included, are worth today. The position panel shows both prices and says they are estimates from the Treasury curve.
Why does the full price drop on a coupon date?
Because the coupon is paid out: the bond no longer carries that interest inside its price. The money is not lost, it has become cash; the clean price, which leaves accrued interest out, hardly changes that day.
Sources
Last reviewed 2026-10-02 by Sphinx Risk.