Calculators and Unit Conversion

A calculator can do the arithmetic correctly and still answer the wrong question if the units or assumptions are wrong. Before you type a number, write down what it represents.

Check the units first

For temperature, 20 °C and 20 °F are very different starting points. For prices, check whether you want price per item, per kilogram, or per litre. For percentages, ask “percent of what?” before calculating.

Treat estimates as estimates

Loan payments depend on rate, term, and the repayment model. Take-home pay depends on local rules and personal circumstances. Use the result to compare possibilities, then check important decisions against the actual agreement or official source.

Related tools

• Number Base Converter — Convert integers between binary, octal, decimal and hex.
• Benchmark Builder — Compare a set of measured values and their ratios.
• Currency Formatter — Format a number as a currency amount with thousand separators and a symbol, in Indonesian or English style.
• Discount Calculator — Work out a final price, a discount percent, or the original price from a discount and a final price.
• Fuel Economy Converter — Convert fuel economy between km/L, L/100 km and US or UK MPG.
• Interest Calculator — Calculate deposit or loan interest after tax, with flat, effective, annuity, compound, tiered, step-up and floating methods.
• Loan Calculator — Work out a fixed-rate loan payment, its amortisation schedule and the interest saved by paying extra.
• Math Evaluator — Evaluate a mathematical expression, with variables and functions.
• Roman Numerals — Convert between Roman numerals and decimal numbers.
• Take-Home Pay Calculator — Estimate Indonesian net salary from gross pay, with PPh 21 and the employee share of BPJS broken out.
• Temperature Converter — Convert between Celsius, Fahrenheit and Kelvin.
• Unit Price Comparator — Compare products by unit price so different pack sizes can be ranked on the same scale.