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Calculators that show their working
CalcTypes is an independent collection of free calculators and plain-English guides. Every tool shows the formula it uses, the assumptions behind it and, where it matters, a step-by-step working, so you can check a result instead of trusting a black box.
Our most-used tools answer everyday questions: how many calories a growing child needs (Child TDEE Calculator), whether a child’s BMI is healthy for their age (CDC Child & Teen BMI Calculator), how much sugar is on a label (Sugar Grams to Teaspoons), what a loan or tax bill costs in India (EMI, Income Tax), how an estate is shared under Islamic law (Islamic Inheritance) and how to solve optimisation problems step by step (Transportation Problem, Linear Programming).
Health and nutrition tools follow published references such as the CDC growth charts, the 2023 National Academies energy equations and WHO and AHA sugar guidance; tax tools follow the Income-tax Act and the current Finance Act. Formulas are tested against known worked examples before publication, and specialist reviewers check selected tools. If a result looks wrong, tell us — fixes are recorded under our corrections policy.
Results are estimates for learning and planning, not medical, legal, tax or financial advice. See how we build and check calculators.