If you hold a US TIPS (Treasury Inflation-Protected Securities), you can use this online tool to calculate its inflation adjusted par value (principle) and interest on each interest payment date.

Inflation adjusted par values and interests calculated by FYIcenter.com:

Dated date: 2021-01-15
Maturity date: 2031-01-15
Coupon rate: 3.0000%
Par value: $1,000.00

Interests are paid 2:
      Date   Ref CPI Ratio       Par Value      Interest
---------- --------- ----- --------------- -------------
2021-01-15 260.31619 1.000       $1,000.00    Dated date
2021-07-15 268.02090 1.030       $1,029.60        $15.44
2022-01-15 277.20274 1.065       $1,064.87        $15.97
2022-07-15 290.54829 1.116       $1,116.14        $16.74
2023-01-15 297.87606 1.144       $1,144.29        $17.16
2023-07-15 303.70803 1.167       $1,166.69        $17.50
2024-01-15 307.39100 1.181       $1,180.84        $17.71
2024-07-15 313.78329 1.205       $1,205.39        $18.08
2025-01-15 315.58677 1.212       $1,212.32        $18.18
2025-07-15 321.09758 1.233       $1,233.49        $18.50
2026-01-15 324.93471 1.248       $1,248.23        $18.72
2026-07-15       TBD   TBD             TBD           TBD
2027-01-15       TBD   TBD             TBD           TBD
2027-07-15       TBD   TBD             TBD           TBD
2028-01-15       TBD   TBD             TBD           TBD
2028-07-15       TBD   TBD             TBD           TBD
2029-01-15       TBD   TBD             TBD           TBD
2029-07-15       TBD   TBD             TBD           TBD
2030-01-15       TBD   TBD             TBD           TBD
2030-07-15       TBD   TBD             TBD           TBD
2031-01-15       TBD   TBD             TBD           TBD
---------- --------- ----- --------------- -------------
      Date   Ref CPI Ratio       Par Value      Interest

The following formulas are used in the above calculations:

$P_t={\displaystyle \frac{{\mathrm{CPI}}_t}{{\mathrm{CPI}}_o}}\times P_o$
$P_t=\text{Current Principal}$
$P_o=\text{Original Principal}$
${\mathrm{CPI}}_t=\text{Current Reference CPI}$
${\mathrm{CPI}}_o=\text{Original Reference CPI}$

For more details, see "Interest Calculation on US TIPS" tutorial.

⇒ CUSIP Search/Lookup on US Treasury Securities

⇐ Imputed Interest/DOI Calculator for T-STRIPS

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