UK savings calculators
Thirteen calculators built for UK wrappers and rules — ISA, SIPP, LISA, GIA, pension drawdown, debt payoff — with AI explanations of what your numbers actually mean.
All savings calculators
From your first ISA contribution to drawing down your pension — every UK savings and investing decision in one place.
ISA vs SIPP vs GIA
Compare wrappers by your marginal tax rate
Compound interest
Long-term growth with regular contributions
Pension contribution
Tax-optimal amount with relief and salary sacrifice
Investment CAGR
True annualised return on your portfolio
Savings goal
Monthly amount needed to hit your target
Loan calculator
Monthly payments and total interest on UK loans
Emergency fund
Months of expenses you should keep in cash
Credit card payoff
Years and interest on minimum payments
LISA vs HTB vs S&S ISA
First-time buyer deposit wrapper compared
Debt avalanche vs snowball
Faster payoff strategy across multiple debts
FIRE number
Portfolio size to retire early using the 4% rule
Pension drawdown
How long your pot lasts at chosen withdrawal rate
Annuity vs drawdown
Guaranteed income against flexible withdrawal
About savings calculators on Calclens
Calclens builds UK savings and investing calculators that go one step further than the rest of the web — every result comes with a plain-English AI explanation, generated on demand. The calculation runs instantly in your browser. The AI layer is optional.
UK savings is a wrapper game. Where you put your money — an ISA, a SIPP, a Lifetime ISA, a General Investment Account — matters as much as the underlying investment. SIPPs get tax relief in, but pay tax out. ISAs are the opposite. LISAs add a 25% government bonus but lock you in until 60 or a first home below £450k. Drawdown later in life gets tangled with the Money Purchase Annual Allowance and sequence of returns risk. Generic global calculators ignore all of this. Ours don’t.
What makes these savings calculators different
- Wrapper-aware maths — ISA, SIPP, LISA, GIA and pension drawdown all work differently and the calculators reflect that
- Marginal rate applied — pension and SIPP relief depends on whether you’re a basic, higher or additional rate taxpayer
- Real retirement modelling — the pension drawdown calculator factors in sequence of returns and tax-efficient withdrawal order, not just a flat 4% rule
- Debt strategy too — before saving, sometimes paying off a 22% APR credit card wins; the credit card and debt strategy calculators show when
- AI explanation layer — powered by Claude (Anthropic), explained on the how AI works page
- Free forever — no sign-up, no accounts, no display ads, no affiliate links to fund managers or platforms
- Built in public — sources from HMRC, MoneyHelper and FCA, documented on our methodology page
Which savings calculator should I use?
I have spare cash. Where should it go?
Start with the ISA vs SIPP vs GIA calculator — the right wrapper depends on your marginal tax rate, your timeframe and whether you need access before 55-57. If you also have expensive debt, run the credit card payoff calculator first — clearing a 22% APR card almost always beats investing.
How much should I keep in an emergency fund?
The emergency fund calculator works out the right size for your situation — usually 3 to 6 months of essential expenses, but more if you have dependants, a mortgage, or unstable income. It suggests where to hold it — an instant-access savings account with FSCS protection, not investments.
I’m a first-time buyer. LISA, Help to Buy or S&S ISA?
The LISA vs Help to Buy vs S&S ISA calculator compares all three for a deposit. LISA gives a 25% government bonus but caps the property at £450k. Help to Buy ISA is closed to new accounts but existing ones still work. A Stocks & Shares ISA has more upside over five-plus years but more downside risk.
How much do I need to retire early?
The FIRE number calculator works out your target portfolio using the 4% rule, adjusted for UK reality — ISA access from any age, SIPP locked until 55-57, State Pension kicking in at 67-68. The number you need depends heavily on where your money sits.
I’m near retirement. Annuity or drawdown?
The annuity vs drawdown calculator compares a guaranteed lifetime income against flexible drawdown from the same pot. Annuities trade upside for certainty — useful if you’re worried about longevity or sequence risk. The drawdown calculator projects how long your pot lasts at chosen withdrawal rates.
I have multiple debts. Which to clear first?
The avalanche vs snowball calculator compares both methods. Avalanche pays highest APR first — mathematically optimal, saves the most interest. Snowball pays smallest balance first — gives faster wins, helps motivation. The calculator shows the cost difference so you can choose with eyes open.
Are these figures financial advice?
No. The calculators give you working numbers based on current UK rules. The AI explanation provides context, not regulated advice. For a binding decision — structuring your portfolio, picking a SIPP provider, taking pension benefits — speak to an FCA-authorised independent financial adviser.