How We Calculate Your Bond's Value

Every figure this calculator shows comes from one source: the U.S. Bureau of the Fiscal Service's official Savings Bond Value Files dataset — the same public-domain data that powers the government's own TreasuryDirect calculator. We don't estimate, extrapolate, or apply our own interest-rate formulas. This page explains exactly what we do with that data, step by step, so you can see why the number you get matches what a bank would pay.

Step 1 — Pulling the raw tables

The Fiscal Service publishes redemption values as a value per $25 of face value, broken out by bond series, issue year and month, and redemption period (the month you'd be cashing it). We fetch the full dataset directly from the Fiscal Service's own API (fiscaldata.treasury.gov), the same records used to build treasurydirect.gov's calculator, twice a year — in May and November — matching the Treasury's own semiannual publication schedule for new interest-rate periods.

Step 2 — Two states per bond

For every (series, issue month) combination, the data falls into one of two states:

• Still earning: the bond appears in the current six-month redemption cycle, with a distinct per-$25 value for each month in that cycle. Your bond's value ticks up on the 1st of each month as it moves through the table.
• Final maturity reached: the bond no longer appears in the current cycle because it's stopped earning. We record its last published value — the frozen final redemption value — and the period it was published in.

Step 3 — The actual arithmetic

Once we have the per-$25 value for your bond's issue month and today's redemption period, the value shown is simply:

value = (face value ÷ 25) × per-$25 redemption value

No additional rounding, markup, or adjustment is applied on top of that — the per-$25 figures published by the Fiscal Service are already the fully computed, penalty-adjusted numbers. That includes the 3-month early-redemption penalty for bonds under five years old: it's baked into the published table itself, not something we calculate separately, so what you see is what a bank would actually pay if you redeemed today.

Handling bonds that aren't in the tables yet

A newly issued EE or I bond can't be cashed in its first 12 months, so it legitimately has no redemption value published yet. Rather than showing an error, the calculator recognizes this case (issue date within the last year, series EE or I) and tells you the bond isn't redeemable yet, along with the date it becomes eligible.

Final maturity, calculated separately from value

Final maturity — the point a bond stops earning interest for good — is computed directly from the issue date rather than pulled from the value tables: 30 years from issue for Series EE and I bonds, and for Series E, 40 years if issued through November 1965 or 30 years for anything issued after that. This is added purely as informational context alongside the redemption value, so you can see both "what it's worth" and "is it still earning" in the same result.

Where the computation runs

All of this arithmetic happens in your own browser, in JavaScript, against a data file downloaded once when you load the page. Your bond details — series, denomination, issue date, any notes you add — never leave your device or reach our servers; there's no account and no server-side database. See the About page and privacy policy for the full data-handling picture.

Limitations, stated plainly

• We cover Series EE, I, E, and Savings Notes — the paper bond types most people hold. HH/H bonds and older H bonds follow different rules and aren't included.
• Values are only as current as the Fiscal Service's twice-yearly publication; a rate change doesn't reach our tables (or the government's own calculator) until the next scheduled update.
• We reproduce Treasury's numbers faithfully, but if you ever spot a mismatch against the official calculator, tell us the bond's series, denomination, and issue date and we'll check it against the current tables.

→ Check your bond's value now (free)