Category
Tools
Companion guides to every calculator on the site - how each works, what numbers actually matter, and how to read the output.
The site has free calculators for the maths that actually shapes a financial plan: compound interest, FI number, safe withdrawal rate, drawdown survival, debt snowball vs avalanche, mortgage overpayment, take-home pay, stamp duty. Each one has a written guide that explains what the tool does, what the inputs really mean, and how to interpret a result that doesn't look how you expected.
These articles are useful in two situations. First, when a calculator gives you a number that feels wrong and you want to understand the assumptions behind it. Second, when you want a worked example before opening the tool yourself.
Start with the compound interest guide for the foundational maths, the drawdown calculator if you're modelling retirement, or debt payoff if you're choosing between snowball and avalanche.
5 articles
HMRC Tax Calculator UK 2026/27: Which One You Need
HMRC has seven different tax calculators. None model salary sacrifice. A £110k earner running the official tool misses £6,000+ in legal savings.
Average Net Worth by Age UK 2026: Where You Actually Stand
The 'average' UK net worth at 55 is roughly double the median. The top 10% pull the mean up. Here is where half the country actually stands, age group by age group.
Income Tax Calculator UK 2026/27: What the Tools Skip
Earn between £100k and £125,140? Your effective income tax rate is 60%. A £105k earner pays more on each extra pound than someone on £200k. Here is the maths.
Financial Literacy Quiz: Test Your Money Knowledge
You probably overrate your money knowledge. Most UK adults do. Three basic questions on inflation, interest and risk decide if your confidence is real or just noise.
Mortgage Overpayment Calculator: Save Thousands in Interest
An extra £200 a month against your mortgage. Most people refuse to do the sum because the answer makes the case for ordering takeaways feel obscene.