Fixed Rate Bond Calculator
Calculate how much you will earn from a fixed-rate savings bond. Compare different terms and rates.
Reviewed by Richard Ross · Last updated April 2026
How Fixed Rate Bond Calculator works
AER vs gross rate
AER (Annual Equivalent Rate) standardises rates for comparison purposes, accounting for compounding. Gross rate is the interest rate before tax and compounding adjustment. For a bond paying interest monthly, the gross monthly rate is lower than the AER. Use AER to compare products.
Fixed rate bonds vs easy access
Fixed-rate bonds typically pay higher rates than easy-access accounts in exchange for locking up your money for the term. You cannot usually access funds during the term without a penalty. Weigh the rate premium against your need for liquidity.
FSCS protection
UK savings up to £85,000 per person, per authorised institution are protected by the Financial Services Compensation Scheme (FSCS). If you have over £85,000 to save, spread it across multiple providers.
Fixed rate bonds and the UK savings landscape
Fixed-rate bonds are offered by high-street banks, building societies, challenger banks (e.g. Atom, Aldermore, Tandem), and NS&I. In 2025, 1-year fixed bonds from competitive providers are paying 4.5–5.2% AER, meaningfully above most easy-access accounts. NS&I Guaranteed Growth Bonds and Guaranteed Income Bonds are government-backed with no FSCS cap — useful for deposits above £85,000. ISA versions (Fixed-term Cash ISAs) deliver the same rate entirely tax-free, making them the optimal structure for higher-rate taxpayers.
Laddering fixed-rate bonds
A popular UK strategy is bond laddering: splitting a lump sum across bonds with staggered maturity dates (e.g., 1-year, 2-year, 3-year). This avoids locking all savings at a single rate and ensures a portion matures each year, providing liquidity. If rates rise, maturing bonds can be reinvested at higher rates. If rates fall, longer-term bonds continue earning the higher locked rate. Laddering smooths interest rate risk across the portfolio.
Source: FCA — Savings accounts guide (fca.org.uk). NS&I — Guaranteed Growth Bonds (nsandi.com). FSCS — Deposit protection limit (fscs.org.uk). Bank of England — savings rate data (bankofengland.co.uk).
Frequently asked questions
What is a fixed-rate savings bond?
A fixed-rate bond is a savings account where you deposit a lump sum for a set period (typically 6 months to 5 years) at a guaranteed interest rate. You cannot usually access the money before maturity without a penalty.
Are fixed-rate bonds safe?
Yes, if held with a UK-authorised bank or building society. The FSCS protects deposits up to £85,000 per person per institution. Look for the FSCS logo or check the FCA register.
Should I lock money in a fixed rate bond or leave it in easy access?
If you will not need the money for the bond term, a fixed rate typically pays a higher rate. Easy access is better for emergency funds or money you might need. Compare the AERs when deciding.
What happens when a fixed rate bond matures?
At maturity, the bond pays out the deposit plus interest. Most providers automatically roll over into a new bond or move to an easy-access account if you don't instruct them. Set a reminder to compare rates and reinvest at the best available rate.
What is the maximum amount I can put in a fixed-rate bond?
There is no legal maximum, but FSCS protection caps at £85,000 per person per institution. For sums above this, use multiple providers or consider NS&I fixed bonds, which are backed by HM Treasury with no protection limit. NS&I Guaranteed Growth Bonds are available from £500 up to £1 million per person.
Can I put a fixed-rate bond inside an ISA?
Yes — fixed-term Cash ISAs work in the same way as fixed-rate bonds but shelter all interest from tax. They are particularly valuable for higher-rate taxpayers whose PSA of £500 is quickly exceeded. You can contribute up to £20,000 per year into ISAs, and the balance can be held in a fixed-term ISA at a competitive locked rate.
What happens to my money if the bank fails during a fixed-rate bond term?
Your money is protected by the Financial Services Compensation Scheme (FSCS) up to £85,000 per authorised institution. If the bank fails, FSCS compensates you within 7 days for the full covered amount including any accrued interest. Always check that the provider is FSCS-protected (regulated by the FCA or PRA) before depositing. Some banks operate under the same FSCS licence — for example, Halifax and Bank of Scotland share one £85,000 limit.
Are fixed-rate bonds better than premium bonds?
Fixed-rate bonds offer certainty — you know exactly what return you will get. Premium bonds offer tax-free prizes but the average prize rate (currently equivalent to around 4.4%) is not guaranteed and varies monthly. If you are a non-taxpayer or a basic-rate taxpayer within your Personal Savings Allowance (£1,000 for basic-rate), a competitive fixed-rate bond will often match or beat premium bonds. Higher-rate taxpayers with large savings balances tend to benefit more from premium bonds' tax-free status.
Can I add money to a fixed-rate bond after opening it?
Usually no. Most fixed-rate bonds require you to deposit the full amount at opening and do not accept top-up deposits during the term. This is one of their key differences from easy-access accounts. Some providers offer a brief funding window (typically 14-30 days) during which you can add funds, but once closed, the balance is fixed for the duration. If you want flexibility, a notice account or cash ISA may be more suitable.
How is interest from a fixed-rate bond taxed?
Interest from fixed-rate bonds is taxable income, added to your total income for the year. Basic-rate taxpayers have a Personal Savings Allowance of £1,000; higher-rate taxpayers £500; additional-rate taxpayers £0. Interest earned above your PSA is taxed at your marginal rate. For large balances, a Cash ISA may be more tax-efficient even if the advertised rate is slightly lower, because ISA interest is completely tax-free.
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