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Calculators

Browse free tools in the calculators category. Everything runs locally in your browser — no account required.

PDF & documents

Developer tools

Percentage calculatorFind a percent of a number, percent change, and share of total.

Age calculatorExact age in years, months, and days.

BMI calculatorBody mass index with a WHO category.

Date calculatorAdd or subtract days, weeks, months; note business-day limits.

Days between datesCount calendar days, weeks, or months between two dates.

Discount calculatorStacked discounts, sale price, and amount saved.

Tip calculatorTip by region, split the bill evenly or by share.

VAT calculatorAdd or remove EU VAT, net/gross, and deductible input VAT.

Calorie calculatorTDEE from Mifflin-St Jeor with deficit, surplus, and macro splits.

Salary calculatorGross to net with progressive tax brackets — generic international model.

Loan calculatorEqual vs decreasing payments, APR, and total interest cost.

Mortgage calculatorMonthly payment, LTV, affordability, and side-by-side offer comparison.

Compound interest calculatorCompound vs simple growth, contributions, and Rule of 72.

Simple interest calculatorCompute interest: I = P × r × t without compounding.

Time calculatorAdd and subtract hours, minutes, and seconds.

Working hours calculatorCalculate hours worked from start, end, and break times.

Fuel cost calculatorTrip cost from distance, l/100km or MPG, and fuel price.

Pace calculatorMin/km vs min/mi, finish times, and training zone paces.

Paint calculatorRuns locally in your browser.

Tile calculatorRuns locally in your browser.

Flooring calculatorRuns locally in your browser.

Concrete calculatorRuns locally in your browser.

Fence calculatorRuns locally in your browser.

Electricity cost calculatorRuns locally in your browser.

Power consumption calculatorRuns locally in your browser.

Ohm's law calculatorRuns locally in your browser.

Battery runtime calculatorRuns locally in your browser.

Tire size calculatorRuns locally in your browser.

Recipe scalerRuns locally in your browser.

Business days calculatorRuns locally in your browser.

Hours calculatorRuns locally in your browser.

Fraction calculatorRuns locally in your browser.

Ratio calculatorRuns locally in your browser.

Profit margin calculatorRuns locally in your browser.

Break-even calculatorRuns locally in your browser.

Percentage change calculatorFind percent increase or decrease between two values.

BMR calculatorCompare Harris-Benedict and Mifflin-St Jeor; see BMR vs TDEE.

Ideal weight calculatorDevine, Robinson & Miller IBW formulas compared with BMI context.

Grade calculatorWeighted averages, GPA, and final grade estimates.

ROI calculatorReturn on investment %, annualized ROI, ROI vs ROAS.

Rule of three calculatorSolve direct and inverse proportions — if A is to B, then C is to ?

Sleep calculatorWake times aligned to 90-minute sleep cycles and ~15 min fall-asleep time.

Due date calculatorNaegele's rule, trimester dates, and key pregnancy milestones.

This page lists calculators tools available on tool-nest.site. Most tools do not upload your files — calculations and conversions happen on your device.

Each tool has its own page with instructions, examples and FAQ. Return to the full catalog to browse all categories.