Guide collection
Tools
Free calculators and interactive tools from Rational GB.
Salary Sacrifice Pension Calculator UK: Take-Home Pay and NI Saving
A UK salary sacrifice pension calculator that shows how much goes into your pension, how far your take-home pay actually falls, and the employee and employer National Insurance saving that a normal contribution never gives you.
Read guidePension Drawdown Calculator UK: How Long Will My Pot Last?
A UK pension drawdown calculator that shows how many years your pot lasts, and the age it runs dry, once you draw an income from it, let it grow after charges and increase what you take each year with inflation.
Read guideLifetime ISA Calculator UK: Bonus, Growth and Exit Charge
See your Lifetime ISA pot at any age: contributions, the 25% government bonus and growth, plus what the 25% withdrawal charge leaves if you cash out early.
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No. 04
Investment Platform Fee Calculator UK: Percentage vs Flat Fee
Free UK investment platform fee calculator: enter your pot size and we work out the yearly cost on Trading 212, InvestEngine, Vanguard, AJ Bell, HL and interactive investor, ranked cheapest first.
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No. 05
Investment Growth Calculator UK: Project Your ISA or SIPP Pot
A UK investment growth calculator that projects your ISA or SIPP pot from a starting sum and monthly contributions, with fees and inflation deducted so you see the real, spendable value.
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No. 06
Pension Tax Relief Calculator UK: Basic, Higher and Additional Rate
A UK pension tax relief calculator that shows the real cost of a SIPP or pension contribution after 20% relief at source plus any higher or additional rate relief you claim back through Self Assessment.
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No. 07
How Long to Reach Your Investment Target: ISA and SIPP Time Calculator
Work out how long to reach 100k or any investment target, from your starting pot, monthly contribution and expected return, with the monthly amount that would get you there faster.
Read guideDividend Tax Calculator UK 2025/26: What You Owe on Your Dividends
A UK dividend tax calculator for 2025/26 that uses your other income to stack your dividends into the right bands, applies the 500 pound dividend allowance, and shows the tax due at 8.75, 33.75 and 39.35 percent.
Read guideCapital Gains Tax Calculator UK 2025/26: What You Owe on Shares and Funds
A UK Capital Gains Tax calculator for 2025/26 that deducts the 3,000 pound annual exempt amount, uses your other income to fill the basic rate band, and splits your gain across the 18 and 24 percent CGT rates for shares and funds.
Read guideHow Much Do I Need to Retire? UK Retirement Number Calculator
Free UK calculator: enter the yearly income you want in retirement and get the pot you need, using a safe withdrawal rate and, optionally, the State Pension.
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