CD Ladder Calculator
CD rung sizes, blended APY, and yearly interest.
What it does
A CD ladder turns one lockup into yearly liquidity. Split $10,000 across 1- to 5-year CDs and one $2,000 rung frees up every year while the rest keeps earning. New cash rolls into a fresh top rung, so the ladder climbs with rates.
The tool above sizes any ladder. Enter the total, rung count, and the low-high rate band, and it prints per-rung size, blended APY, and yearly interest. Defaults give $2,000 rungs at 4.50 % blended for $450 a year.
Banking guides back the pieces. FDIC shopping guidance explains terms from months to five-plus years with early redemption fees, and CFPB defines the CD bargain: keep money parked for a set time for a set rate. Equal weights make the blended rate a plain average.
Ladders beat single CDs on flexibility, not yield. A lone 5-year CD may pay a touch more, but breaking it early forfeits months of interest. The ladder keeps one rung near maturity always, so surprises cost nothing.
How to use
- Enter the ladder total.
- Enter the rung count.
- Enter the low and high rung APYs.
- Read per-rung size first.
- Read blended APY and yearly interest.
- Reinvest maturing rungs at top rates.
Formula
- total
- Ladder total in dollars, 100 and up.
- rungs
- Yearly rungs, 2 to 10.
- low/high
- Short and long end APYs in percent.
Equal rungs make the weighted mean a simple average. FDIC and CFPB confirm term, rate, and penalty concepts behind the math.
Worked example
Example: $10,000, 5 rungs
Defaults: $10,000 over 5 rungs at 4.5 %.
- Inputs: $10,000 total, 5 rungs, 4.5 % flat curve.
- Per rung: 10,000 / 5 = $2,000.
- Blended: (4.5 + 4.5) / 2 = 4.50 %.
- Yearly interest: 10,000 x 4.5 / 100 = $450.
- Tool shows $2,000.00 /rung, $450.00 /yr, 4.50% blended APY.
Reference table
| Total / Rungs | Blended | Interest/yr |
|---|---|---|
| $10,000 / 5 at 4.5 | 4.50 % | $450 |
| $15,000 / 3 at 4.0-5.0 | 4.50 % | $675 |
| $20,000 / 4 at 3.5-5.0 | 4.25 % | $850 |
Limits
- Rate math only. Penalties and taxes excluded.
- Flat band assumed between low and high.
- Callable and bump features ignored.
- Reinvestment rates unknown in advance.
Common mistakes
- Laddering without an emergency fund first.
- Chasing the top rate past the penalty terms.
- Uneven rungs that break the average.
- Forgetting taxes on the interest.
- Letting matured rungs sit at low renewal rates.
Try it yourself
Quick checks. Answers sit tucked under each question.
$15,000 over 3 rungs, 4.0 to 5.0 %?
Per rung 15,000 / 3 = $5,000. Blended (4.0+5.0)/2 = 4.50 %. Interest 15,000 x 4.5 % = $675.
$20,000 over 4 rungs, 3.5 to 5.0 %?
Per rung 20,000 / 4 = $5,000. Blended (3.5+5.0)/2 = 4.25 %. Interest 20,000 x 4.25 % = $850.
Questions
How much goes in each rung?
Total over rungs. $10,000 over 5 gives $2,000 per rung maturing yearly.
What is blended APY?
Mean of the low and high rung rates. A 4.0 to 5.0 ladder blends 4.50 %.
How much interest yearly?
Total times blended over 100. Here $10,000 x 4.5 % = $450 a year.
Why ladder instead of one CD?
Yearly access to one rung without breaking the rest. Five rungs means money frees up every year.
What if I need money early?
Early withdrawals cost a penalty, often months of interest. Laddering avoids breaking terms.
Do ladders follow rising rates?
Yes. Reinvest each matured rung at the new top rate to ride rising rates.