Free online tools
Use CalculatorToolBase for fast, free calculators and converters that show formulas, examples, assumptions, and limitations.
Tool categories
Tools are grouped by everyday task so people and search agents can find the right calculator without guessing a formula name.
Math
Percentages, percentage change, and quick everyday math.
3 calculatorsShopping
Tips, bill splitting, discounts, and simple purchase checks.
4 calculatorsUnits and Cooking
Common units, kitchen measures, and ingredient conversions.
3 calculatorsTime and Date
Durations, date gaps, ages, and schedule math.
5 calculatorsHome Projects
Room area, paint, tile, flooring, and wallpaper estimates.
4 calculatorsEnergy and Travel
Electricity cost, appliance running cost, fuel cost, and travel time.
Common tools
Start with broad calculators that answer frequent math, unit, date, shopping, home project, and travel questions.
Percentage calculator
Calculate percentage of a value, part-of-whole percentage, reverse percentages, add/subtract percentages, and percentage change with guided modes.
Unit converter
Convert common length, area, weight, temperature, volume, speed, pressure, storage, energy, power, time, data rate, fuel economy, and angle units.
Date difference calculator
Calculate days, weeks, months, inclusive date counts, and weekday counts between two dates.
Discount calculator
Calculate sale price after stacked discounts, coupon amount, tax, and shipping.
Paint calculator
Estimate paint from room dimensions, openings, coats, coverage, waste, and container size.
Fuel cost calculator
Estimate fuel needed, fuel cost, round trip cost, shared cost, tolls, and parking.
Scope and safety
CalculatorToolBase focuses on low-stakes arithmetic and planning estimates. It does not provide medical, legal, tax, investment, loan, mortgage, insurance, engineering, or other professional advice.