# sitea.biz

> 15 independent guides to online calculators, plus five browser-based calculators and a directory of independent mini projects, in twelve languages. Every calculation runs on the visitor's device; nothing is uploaded.

Contact: contactmail.bsam@gmail.com
Languages: en (https://sitea.biz/), de (https://sitea.biz/de), es (https://sitea.biz/es), fr (https://sitea.biz/fr), hi (https://sitea.biz/hi), id (https://sitea.biz/id), it (https://sitea.biz/it), nl (https://sitea.biz/nl), pl (https://sitea.biz/pl), pt (https://sitea.biz/pt), sv (https://sitea.biz/sv), tr (https://sitea.biz/tr)

## Guides (https://sitea.biz/guides)

- [Unit Prices: Compare Supermarket Costs with Online Calculators](https://sitea.biz/guides/unit-price-comparison-guide): Learn how to compare supermarket unit prices, spot misleading shelf labels, and decide when a bigger pack, multibuy or concentrate saves you money. — Everyday money, Reviewed 2026-08-09.
- [Splitting the Bill with Online Calculators: Equal or by Item](https://sitea.biz/guides/splitting-the-bill-fairly): Learn when to split a restaurant bill equally, when to pay only for what you ordered, and how to handle shared wine and service charges fairly. — Everyday money, Reviewed 2026-08-09.
- [Tipping Around the World: A Practical Guide with Online Calculators](https://sitea.biz/guides/tipping-guide-by-country): Learn when, where and how much to tip in restaurants worldwide, and use free online calculators to split a bill and check a service charge before you pay. — Everyday money, Reviewed 2026-08-09.
- [Macros Explained: Protein, Carbs, Fat and Online Calculators](https://sitea.biz/guides/macros-and-protein-guide): A plain guide to turning macro percentages into grams, why protein matters most, and what online calculators can and cannot tell you. — Health calculators, Reviewed 2026-08-08.
- [Daily Calorie Needs: What Online Calculators Get Wrong (and Right)](https://sitea.biz/guides/daily-calorie-needs): Learn how daily calorie calculators estimate your needs, why the number drifts over time, and when to see a dietitian rather than trust a formula. — Health calculators, Reviewed 2026-08-08.
- [What BMI Can and Cannot Tell You: Online Calculators Explained](https://sitea.biz/guides/bmi-explained): BMI is the world’s most-used weight number, but it is not a diagnosis. Learn the formula, the band limits, who it misclassifies, and a more useful second check. — Health calculators, Reviewed 2026-08-08.
- [Adding and Removing VAT: A Plain Guide for Online Calculators](https://sitea.biz/guides/how-to-add-and-remove-vat): Learn how to add and remove VAT correctly: why you divide by 1 + rate, the four-unit mistake, and the margin-versus-markup trap on the same invoice. — Percentages and tax, Reviewed 2026-08-07.
- [Sale Maths: Online Calculators for Stacked Discounts and Real Savings](https://sitea.biz/guides/discount-and-sale-maths): Learn how retailers phrase discounts so you can check the real saving instantly with online calculators and unit-price comparisons. — Percentages and tax, Reviewed 2026-08-07.
- [Percentage Calculations Explained: Online Calculators and Four Sums](https://sitea.biz/guides/percentage-calculations-explained): Learn the four percentage calculations everyone confuses, with worked examples and formulas so you pick the right base every time. — Percentages and tax, Reviewed 2026-08-07.
- [Plan a Savings Goal That Actually Arrives with Online Calculators](https://sitea.biz/guides/savings-goal-planning): Use online calculators to turn a vague goal into a date: months-to-goal formulas, annual-cost traps and interest over different horizons. — Budgeting and saving, Reviewed 2026-08-06.
- [How Big Should Your Emergency Fund Be? Use Online Calculators to Check](https://sitea.biz/guides/emergency-fund-guide): Find your real essential monthly spending with online calculators, set a months-of-expenses target, and learn where to keep your emergency fund. — Budgeting and saving, Reviewed 2026-08-06.
- [50/30/20 Budget Rule: What Online Calculators Can and Cannot Show](https://sitea.biz/guides/50-30-20-budget-rule): The 50/30/20 rule splits after-tax income into needs, wants and savings, but percentages can mislead when rent or debt is high. This is an honest guide. — Budgeting and saving, Reviewed 2026-08-06.
- [APR vs Interest Rate: Compare with Online Calculators](https://sitea.biz/guides/apr-vs-interest-rate): We explain what APR and interest rate really mean, why identical rates can cost different amounts, and when APR itself misleads. — Loans and credit, Reviewed 2026-08-05.
- [Using Online Mortgage Calculators Without Fooling Yourself](https://sitea.biz/guides/mortgage-calculator-guide): Learn what online mortgage calculators leave out, how the standard repayment formula actually works, and how to compare the true cost of any home loan. — Loans and credit, Reviewed 2026-08-05.
- [How Loan Interest Works: A Practical Guide Using Online Calculators](https://sitea.biz/guides/how-loan-interest-works): Learn how loan interest, amortisation and term length affect total cost. Use browser-based online calculators to test numbers before seeing a lender. — Loans and credit, Reviewed 2026-08-05.

## Topics (https://sitea.biz/topics)

- [Loans and credit](https://sitea.biz/topics/loans-and-credit): How interest actually accumulates, why the same rate produces very different totals, what APR includes that a rate does not, and what an extra payment really saves you. Written for the person about to sign, not the person selling. — 3 guides.
- [Budgeting and saving](https://sitea.biz/topics/budgeting-and-saving): Budgets that survive a real month: what the 50/30/20 rule is good for and where it fails, how big an emergency fund needs to be, and how to work out honestly when a savings goal will actually be reached. — 3 guides.
- [Percentages and tax](https://sitea.biz/topics/percentages-and-tax): Percentage increases, discounts, VAT in and VAT out — the arithmetic everybody thinks they know until a 20 per cent rise followed by a 20 per cent fall does not return them to where they started. — 3 guides.
- [Health calculators](https://sitea.biz/topics/health-calculators): BMI, basal metabolic rate and daily calories: what each number is derived from, how much it can be trusted, and where a population-level formula stops describing an individual person. — 3 guides.
- [Everyday money](https://sitea.biz/topics/everyday-money): Splitting a bill fairly, tipping in a country you have never been to, unit prices in a supermarket, and the small calculations that quietly cost people money every week. — 3 guides.

## Projects in this directory (https://sitea.biz/)

- [Loan & Mortgage Calculator](/tools/loan-calculator): Monthly repayment, total interest and a year-by-year schedule — including what an extra payment saves.
- [Percentage & Discount Calculator](/tools/percentage-calculator): Percentage of, increase and decrease, sale prices, and VAT added or stripped out.
- [Budget & Savings Planner](/tools/budget-planner): Income against expenses, your real savings rate, and how many months until a goal is reached.
- [BMI & Daily Calorie Calculator](/tools/bmi-calorie-calculator): BMI with the healthy weight range for your height, plus daily calories from the Mifflin-St Jeor formula.
- [Tip & Bill Split Calculator](/tools/tip-split-calculator): Split a bill between any number of people, add a tip, and round up without arguing about the change.
- [Mortgage Guides](/topics/loans-and-credit): Fixed against variable, what APR includes, and the questions to ask before you sign.
- [Saving & Investing Basics](/topics/budgeting-and-saving): Emergency funds, compound growth and the difference between saving and investing.
- [VAT & Tax Maths](/topics/percentages-and-tax): Adding and removing VAT, margin against markup, and invoice arithmetic that survives an audit.
- [Fitness Numbers](/topics/health-calculators): Calories, macros and body measurements — what the formulas assume about you.
- [Everyday Money](/topics/everyday-money): Unit prices, tipping customs, bill splitting and the small maths that adds up.

## Free online calculators (https://sitea.biz/tools)

- [Loan & Mortgage Calculator](https://sitea.biz/tools/loan-calculator): Enter the amount, the term and the interest rate to see the monthly repayment, the total interest and a year-by-year schedule of what you still owe — plus what an extra monthly payment would save.
- [Percentage & Discount Calculator](https://sitea.biz/tools/percentage-calculator): Six calculations in one place: a percentage of a number, the change between two numbers, what share one number is of another, a sale price, VAT added, and VAT stripped back out of a gross figure.
- [Budget & Savings Planner](https://sitea.biz/tools/budget-planner): Put your monthly income against what actually leaves the account, see your real savings rate, compare it with the 50/30/20 rule, and find out how many months a savings goal will genuinely take.
- [BMI & Daily Calorie Calculator](https://sitea.biz/tools/bmi-calorie-calculator): Work out your BMI and the healthy weight range for your height, plus your basal metabolic rate, your daily calorie need at your activity level and a target for losing, holding or gaining weight.
- [Tip & Bill Split Calculator](https://sitea.biz/tools/tip-split-calculator): Split a restaurant bill between any number of people, add a tip at whatever rate you like, and round up cleanly so nobody has to hunt for small change.

## Frequently asked questions

### Are these online calculators free?
Yes, and free in the sense people usually mean: no account, no email address, no trial that expires and no result held back for a paid tier. Every calculator on this site opens and works immediately. There is no advertising on the pages either, and — unusually for a site with a loan calculator on it — no "compare offers" button, because we do not pass anyone to lenders. This is a directory, not a lead generator, and the calculators are cheap to run because the work happens in your browser rather than on our servers.

### Do you see the numbers I enter?
No. All five calculators are JavaScript that runs on your device — the salary you type into the budget planner, the debt in the loan calculator and the weight in the BMI tool are never transmitted to us, never stored and never logged. You can verify this by opening your browser's network tab and watching that nothing is sent while you calculate. It is why the calculators need JavaScript on: a server-side version would have to receive your financial and health data first, which is exactly what we are avoiding.

### Which formulas do the calculators use?
Named ones, and each tool says which. Loan repayments use the standard annuity formula, run month by month so the schedule shows real interest rather than an average. Percentages and VAT use ordinary arithmetic, but applied to the correct base — removing VAT divides rather than subtracting. Calories use the Mifflin-St Jeor equation, today's usual choice for non-clinical estimates. BMI is weight divided by height squared. If a calculator will not tell you what it used, you cannot check its answer, and that is a reason to distrust it rather than a detail.

### Can I rely on these numbers for a real decision?
Use them to understand the shape of a decision, not to make it alone. The loan calculator will show you honestly what an extra 100 a month does to a 25-year mortgage, which is genuinely useful before a meeting — but your lender's figure will differ because an APR folds in fees we cannot know about. The calorie estimate carries about a 10 per cent margin between individuals. The BMI number is a screening ratio and not a diagnosis. Everything here is information; the decision, and the document that governs it, are yours.

### How do I get my own calculator listed?
Use the "list your project" form. Tell us what it calculates in a sentence, who it is for, and which subdomain you would like. We look at four things: it must be usable without an account, it should show its working rather than emitting a single unexplained number, it must not hand the user to a lender or advertiser at the moment they get their result, and it must work on a phone. Listing is free, there is no exclusivity, and we translate your card into all twelve languages. We reply either way, including when the answer is no.

### Which languages is this available in?
Twelve: English, German, Spanish, French, Hindi, Indonesian, Italian, Dutch, Polish, Portuguese, Swedish and Turkish. That covers the whole site, not just the front page — every calculator label, every option in every dropdown, every result sentence and every guide. Currency and number formatting follow the language you choose, so a thousands separator looks the way you expect it to. The language switcher keeps you on the page you were reading, and your choice is remembered in your browser without a cookie banner, because it never leaves your device.