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Money guides

Short, plain-English explainers for the decisions behind the calculators.

How Much House Can You Really Afford?

A plain-English guide to working out a home price you can comfortably afford — the 28/36 rule, down payments, and the costs people forget.

Mortgage Amortization, Explained

Why your early mortgage payments are almost all interest, how the balance falls over time, and what extra payments actually do.

Debt Snowball vs. Avalanche: Which Wins?

The two most popular debt-payoff strategies compared — which saves the most money, which keeps you motivated, and how to choose.

The 4% Rule, Explained

What the 4% rule is, where it came from, its limits, and how to use it to size the nest egg you need for retirement or financial independence.

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Money questions, clearly answered. Free calculators that show their work — no sign-up, nothing stored.

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PlainSums' calculators are for general education and planning only. They produce estimates based on the figures you enter and do not account for every fee, tax or change in rate. They are not financial advice — for decisions about your money, speak to a qualified, regulated professional.

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