Everyday Conversions Calculators

Convert everyday s instantly and accurately. Enter your value and unit — see the exact conversion with formula and common equivalents. Free.

Convert knots to mph km/h and m/s. Full formula with variable legend, worked example and step-by-step chemistry solution.

Convert Mach numbers to mph and km/h. Fast and accurate result with formula, step-by-step method and unit overview. Free tool.

Convert between A4 Letter Legal and other paper sizes. Fast and accurate result with formula, step-by-step method and unit overview. Free tool.

Convert pixels to centimetres for any screen resolution. Enter pixels and DPI — get cm, mm, and inches equivalent dimensions. Free.

Convert between Roman numerals and numbers. Fast and accurate result with formula, step-by-step method and unit overview. Free tool.

Estimate download time for any file size and internet speed. Enter file size and speed — see time in seconds, minutes, and hours. Free.

How long a battery lasts at given current draw. Enter your values — see the result with formula, examples, and step-by-step working. Free.

Calculate PayPal, Stripe, and Square transaction fees to find your net payout. Instant result with breakdown, formula and payment schedule. Free financial calculator.

Feels-like temperature from air temperature and wind speed. Enter your figures — see the result with formula and year-by-year breakdown. Free.

Apparent temperature from heat and relative humidity. Formula, worked example and unit conversions included. Instant thermodynamics solver.

Convert troy ounces to grams, kilograms, and avoirdupois ounces. Enter troy oz — get precise weight equivalents for precious metals. Free.

Convert any number to words instantly. Enter your value — get the written form in standard English for up to 15-digit numbers. Free.

Convert color names to hex codes and RGB values. Fast and accurate conversion with formula, worked examples and unit equivalents. Free online tool.

Convert frequency to wavelength for any medium and wave type. Fast and accurate conversion with formula, worked examples and unit equivalents. Free online tool.

Convert cholesterol levels between mg/dL and mmol/L. Fast and accurate conversion with formula, worked examples and unit equivalents. Free online tool.

Convert eye prescription between different notation systems and formats. Fast and accurate conversion with formula, worked examples and unit equivalents. Free online tool.

Convert decibels to power and amplitude ratios. Fast and accurate conversion with formula, worked examples and unit equivalents. Free online tool.

Convert Brix sugar content to specific gravity for brewing. Fast and accurate conversion with formula, worked examples and unit equivalents. Free online tool.

Convert oil density to API gravity and vice versa. Fast and accurate conversion with formula, worked examples and unit equivalents. Free online tool.

Convert Scoville heat units to pepper rating comparisons. Fast and accurate conversion with formula, worked examples and unit equivalents. Free online tool.

Convert between Mohs, Brinell, Rockwell, and Vickers hardness scales. Fast and accurate conversion with formula, worked examples and unit equivalents. Free online tool.