CD vs. savings calculator

Put a certificate of deposit and a high-yield savings account on the same money and see which one actually wins — held to term, and if you have to break the CD early.

How the math works

Both sides use the same growth formula. A rate quoted as an APY already bakes in its compounding, so the balance after a stretch of months is the principal grown at that yield.

Run it once with the CD's APY and once with the savings APY over the CD's term, and the difference is the held-to-term gap. That part is what every bank's calculator shows.

The part they leave out is what happens if you cash the CD out early. Break a CD before maturity and the bank claws back a penalty — most commonly stated as a fixed number of months of interest. The penalty in dollars is:

So the honest comparison isn't CD-at-maturity versus savings. It's CD-minus-penalty versus savings, evaluated at the month you might actually need the cash. The calculator walks month by month and finds the first one where breaking the CD still beats having stayed liquid. If there isn't one, the CD only pays off if you hold every day to term.

Worked example

Take $10,000 and the plain benchmark case: a 12-month CD at the 1.79% FDIC national average against a high-yield savings account at 4.00%.

Held to term, the CD grows to $10,179. The savings account grows to $10,400. The savings account wins by $221 — and you never gave up access to the money for a single day. The penalty math doesn't even come into it, because the "safe, locked" CD lost to the liquid account outright.

That is the trap in comparing a CD to a bank's own savings product. The average CD only looks good next to a 0.41% brick-and-mortar savings rate. Against a real online account paying 4.00%, the average CD is behind before the lock is even priced in. A CD only earns its keep when its own rate clears a competitive savings rate by enough to pay for the loss of access — and then only if you truly hold to maturity.

When this calculator is wrong

The headline number assumes rates sit still. They don't, and that is the whole case for a CD in the first place.

A 1-year CD usually loses to a high-yield savings account once liquidity is priced in: the FDIC national average 12-month CD pays 1.79%, while the best online savings accounts pay 4.00–4.50%. A CD wins only when it is at a competitive online bank rather than a national chain, and when the saver was genuinely never going to touch the money. Most savers move their money sooner than they planned. The exception is a rate-cutting cycle: a CD locks today's rate for the full term, while a savings rate floats down with the Fed. If you expect cuts and your horizon is firm, a competitive CD can hold a rate the savings account won't keep. Here are the other ways the numbers above mislead:

• The penalty can be worse than "months of interest" suggests. On a short CD held only a few weeks, the penalty is often larger than the interest earned, so you get back less than you deposited. The calculator shows this, but read the fine print — some issuers set a flat minimum penalty.
• It assumes one CD, not a ladder. Splitting the deposit across CDs that mature in staggered steps keeps part of the money reachable each year. That changes the liquidity math the single-CD view here can't capture.
• It ignores taxes. CD and savings interest are both taxed as ordinary income the year they accrue, and a CD can hand you a taxable interest bill before you ever see the cash. The after-tax gap is smaller than the pre-tax gap for both.
• FDIC insurance caps at $250,000. Per depositor, per insured bank, per ownership category. Above that at a single bank, neither the CD nor the savings account is fully insured — a reason to spread very large balances, not to pick one product over the other.

What to do with the result

If the CD only wins held to term — no break-even month before maturity — treat that as a firm rule, not a suggestion. It means any early withdrawal turns the CD into the loser. Lock money in a CD only when you can name the date you'll need it and it's after the term ends. For anything you might touch, the savings account's flat, liquid rate is worth more than a slightly higher rate you can't safely reach.

If the CD wins and its break-even month is early in the term, the rate premium is wide enough that a mid-course exit still comes out ahead. That's the case where a CD is doing real work: locking a rate you'd lose to Fed cuts, with enough margin that being wrong about the horizon doesn't cost you. Below that, the practical move for most savers is to keep the cash in a high-yield account paying 4.00–4.50% and skip the lock.

Common questions

Is a CD or a high-yield savings account better right now?

Compare the two rates you can actually get. If a competitive CD's APY clears a competitive savings APY by a wide enough margin to cover the early-withdrawal penalty, and you won't need the money before the term ends, the CD wins. If the rates are close, or there's any chance you touch the money, the liquid savings account is usually the better call.

What is the early-withdrawal penalty on a CD?

It's a charge for cashing out before maturity, almost always stated as a set number of months of interest — often around three months on shorter CDs and six or more on longer ones. On a CD you've held only briefly, the penalty can exceed the interest you earned, so you get back less than you put in.

Does a CD beat savings if interest rates fall?

That's the strongest case for a CD. A CD locks its rate for the whole term; a savings rate floats down as the Fed cuts. If you expect rates to drop and your time horizon is firm, a competitive CD can hold a yield the savings account won't. In a rising-rate stretch the logic flips — the savings account climbs while the CD is stuck.

Should I use a CD ladder instead?

A ladder splits your deposit across CDs maturing at staggered dates, so a slice comes due each year and you're never fully locked. It's a reasonable middle ground when you want more yield than savings without giving up all access. This calculator models a single CD; a ladder needs its own accounting.

Are CDs safe?

A CD at an FDIC-insured bank is protected up to $250,000 per depositor, per bank, per ownership category — the same coverage a savings account gets. "Safe" refers to the deposit insurance, not the return. A CD that trails a savings account after the penalty is safe and still the worse choice.