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Mortgage, BMI, percentage, tip, paycheck, square footage — plus expert finance, health, and business tools. Every calculator ships with formulas, examples, and the math behind the number.
Tools for every business decision
From single-founder pricing math to mid-market unit economics.
Mortgage, loan, interest, savings
BMI, BMR, TDEE, macros, body fat
Percentage, fraction, GPA, age
Length, weight, temperature, volume
Square footage, concrete, paint, tile
Gas mileage, lease, affordability
Tip, sales tax, discount, pace
ROI, LTV, payback period
CAC, ROAS, conversion rate
Fully-loaded employee cost
Runway, pricing, break-even
Most-used calculators
Where founders and operators start.
Calculate the real return on any software purchase — payback, net benefit, and ROI %.
Find the exact unit and revenue volume where your business covers its costs.
What a hire actually costs — salary, taxes, benefits, equipment, and workspace.
Calculate blended CAC, payback period, and the rough LTV : CAC ratio.
Calculate LTV, expected customer lifetime, and the LTV : CAC ratio investors care about.
Estimate your monthly mortgage payment including taxes, insurance, and HOA.
Calculate your monthly car payment, total interest, and full loan cost.
Estimate your monthly payment on a personal or installment loan.
See how your investment grows with monthly contributions and compounding.
Calculate simple interest on a loan or deposit.
Plan how much your savings will grow with regular deposits.
Project your 401(k) balance at retirement including employer match.
See how long it takes to pay off your credit card — and how much interest you'll pay.
See if refinancing your mortgage is worth the closing costs.
Convert an annual salary to an hourly wage based on hours worked per week.
Project an annual salary from an hourly wage.
Estimate take-home pay after federal tax, Social Security, and Medicare.
Calculate your Body Mass Index from height and weight.
Estimate Basal Metabolic Rate — the calories your body burns at rest.
Calculate Total Daily Energy Expenditure — your real daily calorie burn.
Plan a sustainable calorie deficit for fat loss.
Get your daily protein, fat, and carb targets in grams.
Estimate body fat percentage using the US Navy method.
Calculate your ideal weight range using the Devine formula.
Estimate how much water you should drink each day.
Find a percent of a number, or what percent one number is of another.
Calculate the percent increase or decrease between two numbers.
Convert any fraction to a decimal — or back.
Calculate your grade point average from letter grades and credit hours.
Calculate your exact age in years, months, and days.
Find the number of days, weeks, or months between two dates.
Simplify and scale ratios.
Compute mean, variance, and standard deviation from a list of numbers.
Find the mean, median, and sum of a list of numbers.
Convert between meters, feet, miles, inches, kilometers, and more.
Convert pounds, kilograms, ounces, grams, and stone.
Convert Celsius, Fahrenheit, and Kelvin.
Convert liters, gallons, cups, milliliters, and more.
Convert square feet, square meters, acres, and hectares.
Convert mph, km/h, m/s, and knots.
Calculate square footage of a room, lot, or wall.
Estimate how many cubic yards of concrete you need.
Estimate how many gallons of paint you need.
How many tiles you need for a floor or backsplash.
How many cubic yards of mulch your garden bed needs.
Estimate tons or cubic yards of gravel for a driveway or pad.
How many sheets of drywall you need.
Estimate roofing squares for a pitched roof.
Calculate your car's MPG and cost per mile.
Estimate the gas cost of a trip or daily commute.
What price car can you afford based on your monthly budget?
Estimate a monthly lease payment from MSRP, residual, and money factor.
Calculate tips and split the bill between friends.
Calculate sales tax and total price.
Find the sale price after a percent or dollar discount.
Add up hours worked across multiple days.
Calculate pace, time, or distance for any run.
Calculate the age difference between two people.
Measure return on marketing spend across any channel.
Calculate gross margin and markup percentage.
Calculate net profit margin from revenue, costs, and expenses.
Calculate conversion rate from visitors and conversions.
Calculate monthly customer or revenue churn rate.
How many months until a customer pays back their acquisition cost.
Calculators that answer the whole question.
Most tools give you a number and a banner ad. We give you the answer, the math, and what to do next.
Once you know the number, here's what to buy
Opinionated picks per category — not a paid directory.
Deep guides on the math behind real decisions
A practical pricing framework for agencies, consultants, and service businesses.
An opinionated stack — payroll, CRM, accounting, marketing, PM — built on what we'd actually pay for.
Software vendors quote inflated ROI numbers. Here's how to model the real return on a tool before you sign — and after.
The salary on the offer letter is rarely more than 70% of what an employee costs you. Here's the breakdown — and a free calculator.
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