CD Calculator
A fixed sum, a fixed rate, a fixed term — exactly what it grows to.
How this is calculated
value = principal × (1 + r ÷ 12)^(years × 12)
Worked example: $10,000 at 4.5% for 3 years → about $11,440 at maturity, roughly $1,440 of interest. A guaranteed return — just remember inflation nibbles at what it’s worth.
Certainty, in exchange for access
A certificate of deposit — a fixed or notice deposit in other markets — pays a known rate for a fixed term, with the capital guaranteed and, in most countries, protected up to a limit by a deposit insurance scheme. That combination makes it the correct home for money you will genuinely need on a known date: a house deposit next year, school fees next term, an emergency reserve you want to earn something.
It is the wrong home for long-horizon money. Over decades, a rate that reliably trails inflation guarantees a loss of purchasing power with the same certainty it guarantees the capital.
Compounding frequency and the two rates quoted
Providers quote a nominal rate and an effective annual rate, and the gap is compounding. At 6% nominal compounded monthly, the effective rate is 6.17%; compounded daily, marginally more. Compare products on the effective figure, and check whether interest is capitalised into the deposit or paid away — interest paid monthly into a current account does not compound at all, which makes a headline rate misleading for anyone reinvesting.
Early withdrawal, and the penalty that decides the term
Breaking a fixed deposit early typically costs several months of interest, and some products can return less than was deposited. The longer the term, the harsher the penalty tends to be. That penalty, rather than the rate difference, should drive the term choice: a slightly lower rate on a twelve-month deposit is cheaper than a five-year rate you have to break in year two.
Laddering
Splitting a sum across several deposits maturing at intervals — a ladder — gives regular access to a portion of the money without breaking anything, and averages your exposure to the rate cycle. It is the standard answer to "I want the best rate but I might need some of it", and it costs only the small amount of admin involved in running several deposits at once.
Frequently asked questions
CD, fixed deposit — same thing?
Yes — a certificate of deposit (US) and a fixed or term deposit (UK, SA, Australia) are the same idea: you lock money away for a set term at a set rate. This assumes monthly compounding; some pay simple interest at maturity, which is slightly less.
What if I withdraw early?
Most CDs charge an early-withdrawal penalty that can wipe out months of interest, so only commit money you won’t need. If you might, a shorter term or a laddered set of deposits keeps some within reach.