Tools and calculators
Useful numbers, without pretending they are certain.
These tools are built for beginner planning: compounding, mortgage overpayments, Coast FIRE, ISA allowance checks and the other questions that come up once investing starts to feel real.
Each calculator is educational only. The point is to understand the moving parts, not to get a personalised recommendation.
Live now
Calculators you can use today
Each live calculator is designed to make the main moving parts easier to see before you make your own decisions.
Compound Interest Calculator
Estimate how a starting pot, monthly contributions and possible returns could compound over time.
Investment Growth Calculator
Project a portfolio using a starting balance, regular investing, top-ups and annual fee assumptions.
Investment Fee Calculator
Estimate how fund charges and platform fees could reduce a portfolio over time.
Pound-Cost Averaging Calculator
Compare investing a full amount straight away with splitting the same amount into monthly investments.
Mortgage Overpayment Calculator
Estimate how regular or lump sum mortgage overpayments could reduce interest and shorten the term.
Mortgage Overpayment Vs Investing Calculator
Compare mortgage overpayment certainty with an investment return estimate without turning it into advice.
Coast FIRE Calculator
Estimate whether your current invested pot could grow into a future retirement target by itself.
FIRE Number Calculator
Estimate the portfolio size linked to a chosen annual spending level and withdrawal-rate assumption.
Financial Flexibility Calculator
Estimate how many months of essential spending are covered by cash and accessible investments.
ISA Allowance Calculator
Work out how much ISA allowance may be left and what monthly contributions would use it by tax-year end.
Savings Goal Calculator
Estimate the monthly saving needed to reach a target, or how far your current plan may get you.
Emergency Fund Calculator
Estimate an emergency fund target from essential monthly spending and a chosen number of months.
Coming soon
More calculators on the way
I am adding more tools around the questions beginners tend to ask once they start thinking about investing, saving, mortgages and financial flexibility.