We design calculators from a simple principle: start with the rand amount, show the estimated outcome, and reveal technical assumptions only when needed.
Every result explains its assumptions
Electricity and appliance estimates use energy in kilowatt-hours. Petrol estimates use a price per litre and litres per 100 kilometres. Savings projections use a monthly contribution and illustrative compound interest. Home-loan principal is calculated using the present value of monthly instalments.
Why the numbers are examples
Utility prices vary by supplier, user category, region and time. Savings returns and mortgage interest rates depend on financial products and risk. We use explicitly labelled example rates so the tool can work immediately, but we do not imply they are live market prices.
What we do not model
Many calculators simplify taxes, standing charges, usage patterns, installation costs, equipment losses, lender assessments and variable prices. Page-level notes explain the most important exclusions. Actual costs may be materially different.
Privacy-first calculations
Inputs and arithmetic take place in the browser; this build does not have a calculator data backend.
Reviewed: 12 October 2026.
Calculation spot-checks
We test the arithmetic behind everyday results with simple check cases, including zero-growth savings, negative remaining budgets, electricity unit conversion and the reverse-loan formula. New assumptions are not presented as official rates unless a dated supplier source can be verified and credited.
How this site makes money
These calculators are free and currently contain no advertising scripts. In the future, clearly identified advertisements or optional paid features may support the site. Commercial arrangements should not change the calculation formula or turn a hypothetical result into a product recommendation.
Corrections and updates
Calculator models are simplifications. Material bugs should be corrected and dates updated when substantive content or assumptions change. Always compare the estimate with current bills, contracts and official tariffs before acting.