AER (Annual Equivalent Rate)
Plain-English definition of AER (Annual Equivalent Rate) — part of our saving glossary.
Definition
AER is the savings equivalent of APR — the rate of interest you earn on a savings account assuming interest is left in the account to compound. AER allows direct comparison between accounts with different compounding frequencies.
Worked example
Two accounts advertising "4% interest" can deliver different real returns: one paying simple annual interest, another paying 4% AER with monthly compounding. On £10,000 the difference is small in year one (roughly £7) but compounds into meaningfully different balances over a decade.
Why it matters
Savings are the foundation of everything else — you cannot invest, buy a home, or weather a redundancy without a cash buffer. Even modest sums build meaningful resilience if they are parked in the right wrapper and left alone.
Common mistake
Leaving large balances in a current account earning 0–1% is one of the most expensive "default decisions" in personal finance. Over a few years, the opportunity cost versus a simple easy-access account regularly runs into the hundreds of pounds per £10,000 held.
Calculators that use this concept
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See also
- ISA (Individual Savings Account) — An ISA is a UK tax-free savings or investment wrapper. You can contribute up to £20,000 per tax year across Ca…
- Emergency Fund — An emergency fund is cash set aside specifically for income interruption or unexpected major expenses — typica…
- Sinking Fund — A sinking fund is a dedicated savings pot for a predictable future expense — Christmas, a car replacement, ann…
- Premium Bonds — A UK government-backed savings product where returns come as tax-free prize wins rather than fixed interest. T…