Percentage Calculator
Calculate percent of a number, part as percent of whole, percentage change, percentage-point difference, increase/decrease and whole-from-part.
Open calculatorQuick math checks
Use these for quick everyday math when you want the formula shown and common input mistakes flagged.
Decimal to Percent Calculator
Convert a decimal to a percentage.
Open calculatorFraction Calculator
Add two fractions and return a decimal result.
Open calculatorAverage Calculator
Calculate average from sum and count.
Open calculatorStandard Deviation Calculator
Calculate sample or population standard deviation with mean, variance, range, quartiles, median and IQR.
Open calculatorLoans and mortgage planning
These calculators help compare monthly payment, total interest, amortization and payoff scenarios before you make a lending decision.
Loan Calculator
Estimate amortized loan payments, total interest and total cost with a payment schedule.
Open calculatorMortgage Calculator
Estimate mortgage payments with optional taxes, insurance and clear country/region caveats.
Open calculatorAmortization Calculator
Estimate first-month interest and principal split for an amortized loan.
Open calculatorMortgage Payoff Calculator
Estimate months needed to pay off a mortgage with extra monthly payments.
Open calculatorRefinance Calculator
Estimate monthly savings from refinancing a loan.
Open calculatorPMI Calculator
Calculate pmi from user-entered values with a visible formula, assumptions, limitations and source notes. Use dated source values for any market, distribution, regional or price-sensitive input.
Open calculatorHealth and nutrition estimates
These tools are best used as cautious estimates. They keep screening limits, assumptions and medical caveats visible.
BMI Calculator
Estimate body mass index with metric and imperial units, category interpretation and clear limitations.
Open calculatorCalorie Calculator
Estimate daily calorie needs using researched BMR/TDEE methods and activity assumptions.
Open calculatorBMR Calculator
Estimate basal metabolic rate using Mifflin-St Jeor with sex coded as 1 male or 0 female.
Open calculatorTDEE Calculator
Estimate total daily energy expenditure from BMR and activity multiplier.
Open calculatorIdeal Weight Calculator
Estimate ideal body weight using the Devine formula.
Open calculatorProtein Calculator
Calculate daily protein grams from body weight and grams per kilogram.
Open calculatorInvestment growth and value
Use these to test assumptions about compounding, return, inflation and time value without treating projections as guarantees.
Compound Interest Calculator
Project future value from starting amount, contributions, rate, time and compounding frequency.
Open calculatorInvestment Calculator
Project future investment value from starting amount, contributions, rate and time.
Open calculatorROI Calculator
Calculate return on investment percentage from return value and investment cost.
Open calculatorFuture Value Calculator
Calculate future value of a present amount.
Open calculatorPresent Value Calculator
Discount a future value back to today.
Open calculatorRetirement Calculator
Estimate retirement savings trajectory with return, inflation and withdrawal assumptions clearly shown.
Open calculatorDate, time and conversion utilities
These calculators answer common scheduling and conversion questions while making unit, calendar and data-source assumptions clear.
Date Calculator
Add or subtract dates and calculate differences in calendar days with clear date handling.
Open calculatorAge Calculator
Calculate age in years, months and days plus next birthday details.
Open calculatorTime Duration Calculator
Calculate differences between times and add or subtract hours, minutes and seconds.
Open calculatorUnit Converter
Convert common units across length, mass, temperature, volume, area, speed and more.
Open calculatorCurrency Converter
Convert currencies with latest reference rates, historical-date rates, inverse rates, fee/spread estimates and manual fallback mode.
Open calculatorConversion Calculator
Convert a value using a user-entered conversion factor.
Open calculatorBusiness and SaaS metrics
Use these for repeatable definitions of CAC, LTV, MRR, ARR, ROAS, runway and break-even analysis.
Customer Acquisition Cost Calculator
Estimate customer acquisition cost from user-entered values with a visible formula, assumptions, limitations and source notes.
Open calculatorCustomer Lifetime Value Calculator
Calculate customer lifetime value from user-entered values with a visible formula, assumptions, limitations and source notes.
Open calculatorLTV:CAC Ratio Calculator
Calculate ltv:cac ratio from user-entered values with a visible formula, assumptions, limitations and source notes.
Open calculatorMRR Calculator
Calculate mrr from user-entered values with a visible formula, assumptions, limitations and source notes.
Open calculatorARR Calculator
Calculate arr from user-entered values with a visible formula, assumptions, limitations and source notes.
Open calculatorRunway Calculator
Estimate runway from user-entered values with a visible formula, assumptions, limitations and source notes.
Open calculatorBreak-Even Calculator
Estimate break-even units from fixed cost, unit price and variable cost.
Open calculatorConstruction and materials
These tools help turn measurements into material estimates while keeping waste, rounding and field measurement limits visible.
Square Footage Calculator
Calculate area in square feet from length and width in feet.
Open calculatorConcrete Volume Calculator
Estimate concrete volume from length, width and depth.
Open calculatorPaint Cost Calculator
Estimate paint cost from user-entered values with a visible formula, assumptions, limitations and source notes.
Open calculatorFlooring Cost Calculator
Estimate flooring cost from user-entered values with a visible formula, assumptions, limitations and source notes.
Open calculatorTile Calculator
Estimate tile count from area, tile area and waste percent.
Open calculatorRoofing Calculator
Estimate roof surface area from footprint area and pitch factor.
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