CD Calculator: Maturity Value, Interest & APY 2026

How CD interest works

A certificate of deposit is a promise: you hand the bank your money for a fixed term, and the bank pays you a fixed rate for the whole term. The maturity value is what you get back at the end: your deposit plus the interest it earned. The formula is FV = P × (1 + r/n)^(n × T/12), where P is the deposit, r is the nominal annual rate, n is the number of compounding periods a year, and T is the term in months. The interest is FV − P. The rate you enter is the NOMINAL annual rate — the rate the bank advertises — and the APY is what compounding actually pays: APY = (1 + r/n)^n − 1. With monthly compounding at 4.50%, the APY is 4.5940%, so a $10,000 deposit earns $459.40 in a year, not $450.00. CDs lock the money: early withdrawal usually costs interest, which this calculator states but does not model.

At the defaults — a $10,000 deposit, a 4.50% nominal rate, monthly compounding, a 12-month term — the growth factor is 1.04593983, the maturity value is $10,459.40, the interest is $459.40, and the APY is 4.5940%. Check the identity: $10,000.00 + $459.40 = $10,459.40. The same $10,000.00 in a 0.50% savings account (monthly compounding) reaches $10,050.11, so the CD pays $409.28 more. That $409.28 is the unrounded difference: the rounded parts ($10,459.40 − $10,050.11) differ by a cent, $409.29, because each figure was rounded separately. Totals are computed from unrounded values, so rounded parts may differ by a cent from their rounded sum.

The worked example, line by line

Setup: deposit $10,000, nominal rate 4.50%, monthly compounding (n = 12), term 12 months.

Line 1 — the rate per period. 4.50% / 12 = 0.00375 a month. Each month the balance grows by 0.375%.

Line 2 — the growth factor. (1 + 0.00375)^12 = 1.04593983. That is the number $1 grows to in a year at 4.50% compounded monthly.

Line 3 — the maturity value. $10,000 × 1.04593983 = $10,459.40.

Line 4 — the interest. $10,459.40 − $10,000.00 = $459.40. Check: $10,000.00 + $459.40 = $10,459.40.

Line 5 — the APY. (1 + 0.045/12)^12 − 1 = 4.5940%. The APY is higher than the 4.50% nominal rate because each month’s interest earns interest of its own.

Line 6 — the savings comparison. The same $10,000.00 at 0.50% compounded monthly reaches $10,050.11, so the CD pays $409.28 more (unrounded difference; the rounded parts differ by $409.29).

Reverse: to reach $11,000 in 12 months at monthly compounding, the rate would need to be 9.57% (exact 9.5690%); at 9.57% the maturity value is $11,000.11, eleven cents over. The deposit needed to reach $11,000 at 4.50% is $10,516.86 (exact $10,516.8574); at $10,516.86 the maturity value is $11,000.00. It takes 25.46 months, or 2.12 years, to reach $11,000 at 4.50%, and 13.04 months to reach $10,500. The rate needed to reach $10,500 in 12 months is 4.89% (exact 4.8889%); at 4.89% the maturity value is $10,500.11.

Every branch, checked

Deposit $25,000: the maturity value is $26,148.50 and the interest is $1,148.50. Two and a half times the deposit earns two and a half times the interest, because the rate is the same.

Rate 5.00%: the maturity value is $10,511.62 and the interest is $511.62. Half a point of rate adds $52.22 of interest over a year.

Rate 3.00%: the maturity value is $10,304.16 and the interest is $304.16. One and a half points less cost $155.24.

Term 24 months: the maturity value is $10,939.90 and the interest is $939.90. Two years earn a little more than twice the one-year interest, because the second year’s interest is calculated on the first year’s interest as well.

Term 6 months: the maturity value is $10,227.12 and the interest is $227.12. Half the term gives a little less than half the interest, because the interest compounds.

Term 36 months: the maturity value is $11,442.48 and the interest is $1,442.48. Three years at 4.50% turn $10,000 into $11,442.48.

Annual compounding: the maturity value is $10,450.00 and the interest is $450.00. With interest added once, the APY is exactly the nominal rate, 4.5000%.

Quarterly compounding: the maturity value is $10,457.65 and the interest is $457.65. Four additions a year earn $7.65 more than one.

Daily compounding: the maturity value is $10,460.25 and the interest is $460.25. Daily compounding pays the most — $0.85 more than monthly, $2.60 more than quarterly, $10.25 more than annual — but the differences are small at this rate and term.

Deposit $5,000: the maturity value is $5,229.70 and the interest is $229.70. Half the deposit earns exactly half the interest.

Reverse — the other way round: the rate for $11,000 in 12 months is 9.57% (exact 9.5690%); the deposit for $11,000 at 4.50% is $10,516.86 (exact $10,516.8574); the time to $11,000 is 25.46 months (2.12 years); the time to $10,500 is 13.04 months; the rate for $10,500 in 12 months is 4.89% (exact 4.8889%).

What the defaults assume

The model assumes the rate stays fixed for the whole term, the interest compounds at the chosen frequency, and no money is added or withdrawn. It assumes the rate is a nominal annual rate with no fees, no taxes, and no inflation: the $10,459.40 is the nominal maturity value, not what it will buy. It does not model the early-withdrawal penalty: CDs lock the money, and taking it out early usually costs interest. With the rate at 0%, the maturity value is $10,000.00 and the interest is $0.00. With a term of 0 months, the maturity value is $10,000.00, the deposit alone. With a deposit of $0, the maturity value is $0.00. With a deposit of $100,000, the maturity value is $104,593.98. Rounding convention: totals are computed from unrounded values, so rounded parts may differ by a cent from their rounded sum; the exact unrounded reverses (9.5690%, $10,516.8574, 4.8889%) are stated wherever the rounded figures appear.

Output · formula · meaning

Who uses this

• The saver with $10,000 and a 4.50% CD for 12 months: they learn the CD pays $459.40 and matures at $10,459.40 — so they know the APY is 4.5940%, not 4.50%, and they check the savings comparison ($409.28 more than a 0.50% savings account) before deciding the lock-up is worth it.
• The saver aiming for $11,000 in a year: they learn they need a 9.57% rate (exact 9.5690%) or a $10,516.86 deposit (exact $10,516.8574) — so they know the 4.50% CD falls short, and they check the time instead (25.46 months, or 2.12 years) before deciding whether to wait longer or deposit more.
• The saver choosing between monthly and daily compounding: they learn daily pays $10,460.25 against monthly’s $10,459.40 — so they know the difference is $0.85 over a year, and they check the annual figure ($10,450.00) before assuming the frequency matters more than the rate.
• The saver weighing a 3-year CD against a 1-year one: they learn 36 months reaches $11,442.48 — so they know three years earn $1,442.48, and they check the 6-month branch ($10,227.12) before locking the money up for three years.

Accuracy & limitations

The math is exact for the numbers you enter: the maturity value is P × (1 + r/n)^(n × T/12), the interest is FV − P, the APY is (1 + r/n)^n − 1, and the savings comparison is the same deposit at 0.50% compounded monthly. What the model cannot do is predict a real CD rate: check the rate, because CD rates change with the market, and the rate is fixed only once you buy the CD. It assumes the rate stays the same for the whole term, no money is added or withdrawn, and there are no fees, no taxes, and no inflation. It does not model the early-withdrawal penalty: CDs lock the money, and taking it out early usually costs interest. It leaves out the risk that you need the money before the term ends. For the same math with monthly contributions, see compound growth calculator; for a ladder of CDs maturing at different times, see CD ladder calculator.