CD Ladder Calculator

Disclaimer: This calculator is provided for educational and estimation purposes only and does not constitute formal financial advice.

What a CD ladder actually buys

A ladder does not raise your yield. That is the first thing to say plainly, because ladder guides routinely imply otherwise. On a normal upward-sloping rate sheet, splitting $25,000 across five CDs maturing in years one through five earns less than putting all $25,000 into the five-year CD — about $224 less over ten years at these default inputs.

What the ladder buys is cadence. One fifth of the balance comes due every twelve months, penalty-free, forever once the rotation is established. Breaking a real five-year CD early costs months of interest — the certificate of deposit calculator prices exactly that exit cost — whereas a matured rung simply arrives as cash. A ladder is the product you buy when part of a long-term balance might, plausibly, need to become spendable on short notice.

The second benefit is timing diversity. A single long CD commits the whole balance at whatever the rate sheet said on one particular day. A ladder spreads entry across five dates, so no single misread of the rate cycle applies to everything.

The math the calculator runs

Each rung $i$ of the ladder carries its own APY, stepping outward from the shortest quote:

where $s$ is the step per longer rung in percentage points — positive on an upward-sloping curve, negative on an inverted one. Input rates are APYs, not nominal quotes, because banks advertise deposits as APYs; growth applies the monthly-equivalent factor:

When a rung matures, its full proceeds roll into a new longest-term CD at the top-of-curve rate — the reinvestment rule that defines a sustained ladder. Two simplifying assumptions come with it: the rate curve is held static over the whole projection (future rollovers price at today’s longest quote), and matured funds never sit idle between terms. Blended performance reduces to:

For the defaults — five rungs at 4.00% to 4.60% APY projected ten years — that works out to 4.54%, against 4.60% for holding the entire balance in the five-year term the whole time.

The opening ladder, worked

With $25,000 split evenly, each rung’s first maturity looks like this:

First-cycle interest totals $3,508.71 across the five rungs. From month thirteen onward the calendar changes character: rung one re-enters as a fresh five-year CD, and every twelfth month another long-term rung matures and rolls. By year five the original stagger has rebuilt itself entirely out of top-of-curve paper — every active CD now pays 4.60% — while the maturity calendar keeps paying out annually.

The comparison column is the honest benchmark: the same $25,000 locked in the five-year CD from day one, rolled at 4.60% throughout. The ladder’s blended 4.54% converges toward it as the rotation matures but never reaches it inside a fixed horizon, because dollars that started short were earning less than 4.60% during their waiting years.

What the liquidity costs at different horizons

Read the gap against what it purchases. At year ten the ladder has given up $224.41 — about six basis points a year on this balance — and in exchange about $7,795 of face value matures penalty-free every twelve months, with no withdrawal decision attached. Set the same $7,795 loose early from one big long CD instead and the bank charges months of interest for the privilege, whether or not that much interest has accrued yet.

The gap also flattens as horizons extend: $125.36 over two years becomes $351.85 over twenty, while the money involved quintuples. Per dollar, per year, liquidity gets cheaper the longer the ladder runs.

One case reverses the verdict outright. On an inverted curve — short rates above long ones — set the step negative and the ladder finishes ahead: its early rungs earn the rich short-end rates, and nothing about rolling into the longer, lower end retroactively erases that head start. Extended inversions are historically rare, but they do happen, and a ladder is at its most defensible exactly then.

Liquidity is the actual product

It helps to re-price the ladder against its genuine alternative — not one long CD, but keeping the money somewhere that never charges for exits. The high-yield savings calculator runs that comparison directly. High-yield savings typically pays within half a point of the shortest rung and nothing like the longest, so the ladder’s edge over the liquid baseline compounds to real money at scale: versus a savings account tracking rung-one rates at 4.00% for the full horizon, the default ladder’s later years earn closer to 4.60% on every dollar in the book. That is the whole yield story of a ladder, told properly: it lets most of a balance live at long-end rates while behaving, twelve months at a time, like cash you planned for.

If the balance exists to fund several dated obligations — tuition years, insurance renewals, the next car — a sinking fund splits them explicitly by date instead of implicitly by rung length, and pairs naturally with a smaller ladder handling the unallocated remainder.

Practical notes banks won’t lead with

Taxes arrive before the money does. CD interest is taxable as ordinary income in the year credited, not at maturity. Years two through four of this ladder owe tax on interest still locked inside rungs that will not mature for one to three more years. In a taxable account at a meaningful bracket, that drag is a second, quieter yield gap on top of the $224 the model already prices.

Insurance limits multiply with rungs. FDIC coverage caps at $250,000 per depositor, per institution. A large ladder usually wants its rungs spread across several banks — partly for insurance arithmetic, partly because no single institution wins every term on the rate sheet. Five rungs at five banks means five 1099-INTs each January and five calendars to watch; brokered CDs consolidate the paperwork but add secondary-market mechanics worth reading about before buying.

Reinvestment risk is the model’s silent variable. Every rollover here repriced at today’s top quote held constant. If the actual world delivers lower long rates three years out, matured rungs will roll at those lower rates — the classic ladder compromise, accepted in exchange for always having something coming due.

When a ladder is the wrong tool

Laddering is overhead. It earns its keep only when some portion of the money might genuinely be needed early and nobody can say which portion, or when. If the date is known — a house completion, a tax bill — one correctly-sized CD beats a ladder on both yield and fuss. If timing is genuinely unknown, the fully liquid account is worth its smaller APY, full stop. And if the real answer is “this money has no job at all,” no deposit product is the right structure yet; decide the goal first, then pick the term.