Everyday & Conversion Calculators
Quick answers for daily life at home, at the shops and on the road. Convert units, split a bill, price a DIY project or generate a strong password.
11 free calculators · no sign-up · results stay in your browser
- Tip Calculator Popular Tip amount, total and each person's share, with round-up and pre-tax options.
- Discount Calculator Sale price, amount saved, stacked discounts, sales tax and reverse discounts with steps.
- Unit Converter Popular Length, weight, volume, area, temperature, speed, time, data, pressure, energy and fuel economy.
- Temperature Converter Popular Fahrenheit, Celsius, Kelvin and Rankine with formulas and body, oven and weather charts.
- Square Footage Calculator Area in sq ft, m² and sq yd for rooms, L-shapes and whole houses, with flooring cost.
- Concrete Calculator Cubic yards, m³ and bag counts for slabs, footings, walls, post holes and steps.
- Fuel Cost Calculator Trip fuel cost from distance, mpg, km/L or L/100 km and price, split between passengers.
- Electricity Cost Calculator Cost to run any appliance per hour, day, month and year from watts, hours and your rate.
- Password Generator Random 8–128 character passwords made in your browser, with entropy and strength.
- Roman Numeral Converter Numbers to Roman numerals and back, with strict validation and a step-by-step breakdown.
- Dog Age Calculator Dog years to human years by size, with the 2020 DNA-based formula and life stage.
About these calculators
Small calculations come up all day. Split a restaurant bill with the tip calculator, check a sale price with the discount calculator, or convert recipe and travel measurements with the unit converter and the Fahrenheit to Celsius converter.
Planning a home project? The square footage and concrete calculators estimate materials, and the electricity cost and fuel cost calculators show what an appliance or a road trip really costs. Generate a strong random password locally in your browser with the password generator.
A few conversions come up again and again: 1 inch is exactly 2.54 cm, 1 kilogram is about 2.2046 pounds, 1 US gallon is 3.785 litres, and to turn Fahrenheit into Celsius you subtract 32 and multiply by 5/9 (so 98.6 °F is 37 °C). The unit converter uses the exact legal definitions published by NIST for every unit, so results match what you'd get from an engineering reference.
For money on the go, a 15–20% tip is the U.S. norm at sit-down restaurants, while in India and the UK a service charge is often already on the bill, so check before you add more. When comparing sale prices, remember that two discounts stack by multiplying: 20% off and then a further 10% off is 28% off in total, not 30%. Both calculators show the working so you can check the shop's arithmetic.
Home-project tools give material estimates with a waste allowance built in. Concrete is usually ordered with 5–10% extra, and flooring with 10% extra for cuts. Running-cost calculators turn an appliance's wattage and your electricity rate into a monthly cost, or a car's fuel economy and the pump price into a trip cost. You can switch currency for any of them.