All calculators.

Estimate monthly payments, total interest, and full amortization for a home loan.

Monthly payment, interest, and payoff schedule for any fixed-term loan.

Full month-by-month breakdown of principal vs interest for any fixed-term loan.

Solve for monthly payment, term, or loan amount given the other two.

Monthly payment on a car loan including sales tax, trade-in, and down payment.

True Annual Percentage Rate on a loan, including upfront fees.

Compare your current mortgage to a refinance and find the break-even point.

Months to pay off a debt at a chosen monthly payment.

Project a 401(k) balance including your contribution, employer match, and expected return.

Project growth of savings with regular contributions and compounding.

Interest without compounding — useful for short-term loans and bonds.

Compute annualized return (CAGR) and total gain for an investment.

What a future sum is worth in today's dollars at a chosen discount rate.

What a present sum will be worth in the future at a chosen growth rate.

Return on investment as a percentage and annualized rate.

Project your retirement nest egg and monthly income in retirement.

Split a bill, add a tip, and get each person's share.

Compute sales tax on a purchase or reverse-calculate pre-tax price.

Estimate US federal income tax for 2024 brackets (single or married filing jointly).

Convert between hourly, weekly, monthly, and annual pay.

Convert between major currencies using indicative reference rates.

See how purchasing power changes over time at a given inflation rate.

Project a tax-free Roth IRA balance from your annual contribution and expected return.

Estimate a Traditional IRA balance and pre-tax vs after-tax value at retirement.

Required Minimum Distribution from a Traditional IRA or 401(k) using the IRS Uniform Lifetime Table.

Estimate an annual defined-benefit pension from years of service, final salary, and accrual rate.

Future value of an annuity: fixed periodic contributions growing at a chosen rate.

Lifetime annuity payout calculator: the fixed monthly payment a lump sum will produce over a chosen number of years.

Price a fixed-coupon bond from yield-to-maturity, face value, coupon rate, and years to maturity.

Certificate of Deposit maturity value with any compounding frequency.

See how expense ratios erode long-term returns compared with a low-fee alternative.

Internal rate of return for a series of cash flows (initial outflow then yearly inflows).

Years needed to recover an initial investment from equal annual cash flows.

Months to pay off a credit-card balance at a fixed monthly payment, and total interest paid.

Monthly payment needed to pay off a card balance in your chosen number of months.

Compare paying multiple debts separately vs consolidating them into one lower-rate loan.

Loan repayment with optional extra monthly payment — see how much interest and time you save.

Monthly student-loan payment and total cost over the standard 10-year (or custom) repayment plan.

Total cost of a college education adjusted for tuition inflation, and what to save monthly to cover it.

Split take-home income into Needs, Wants, and Savings using the popular 50/30/20 rule.

How much rent you can afford based on the 30% of gross income rule.

Compare the total cost of renting vs buying over a chosen holding period.

Estimate the maximum home price you can afford using front-end and back-end DTI ratios.

Grow a principal with periodic compounding and optional monthly contributions.

Solve for the implied annual interest rate on a loan from the payment amount.

VA-backed mortgage with funding fee financed into the loan.

FHA mortgage with upfront and annual mortgage insurance premiums.

Solve for down payment amount, percentage, or affordable home price.

Cash flow, cap rate, and cash-on-cash return for a rental investment.

Auto lease monthly payment from cap cost, residual, money factor, and tax.

Straight-line, double declining balance, and sum-of-years digits depreciation schedules.

Compare a manufacturer rebate against a promotional low-APR financing offer.

Break down agent commissions and estimate seller net proceeds.

See how extra monthly payments shrink your payoff time and interest.

Estimate your net paycheck after federal, state, FICA, and 401(k) deductions.

Compare filing as two singles versus married filing jointly to see the marriage bonus or penalty.

Estimate US federal estate tax against the 2025 lifetime exemption.

Estimate US Social Security monthly benefit at ages 62, 67 (FRA), and 70.

Find the monthly contribution required to reach a savings target by a given date.

Compute margin, markup, cost, or price — solve any one from the others.

Compute sales commission, with optional tiered rate above a threshold.

Discount future cash flows to a net present value and estimate the internal rate of return.

Solve any time-value-of-money variable: future value, present value, payment, or number of periods.

Add or remove value-added tax at any rate. Works for UK, EU, GCC, and more.

Apply two sequential discounts and an optional tax to find the true final price.

Find the unit and revenue volume at which fixed and variable costs are covered.

Body Mass Index for adults, with WHO category interpretation.

Basal Metabolic Rate via Mifflin-St Jeor — calories your body burns at rest.

Total Daily Energy Expenditure — daily calories needed to maintain, lose, or gain weight.

US Navy method — body fat percentage from tape measurements.

Ideal body weight ranges via Devine, Robinson, and Miller formulas.

Daily protein, carb, and fat targets from a calorie goal.

Daily protein target from body weight and activity level.

Daily carbohydrate target from calorie intake and diet style.

Estimate lean body mass (fat-free mass) using Boer, James, and Hume formulas.

Calories burned in an activity using MET values and body weight.

Convert between pace, speed, distance, and time for running or cycling.

Estimate your 1-rep max from a submaximal set using Epley, Brzycki, and Lombardi formulas.

Estimate due date from last menstrual period (Naegele's rule).

Estimate fertile window from cycle start date.

Daily water target based on body weight and activity.

Target heart rate zones for training (Karvonen method).

IOM-recommended weight gain during pregnancy based on pre-pregnancy BMI.

Estimate conception date from due date or last menstrual period.

Predict next periods, ovulation, and fertile window.

Estimate blood alcohol concentration using the Widmark formula.

Calculate body surface area using Du Bois, Mosteller, or Haycock formulas.

Weight range for a healthy BMI (18.5–24.9) at a given height.

Daily calorie target to reach a weight goal within a timeframe.

Waist-to-hip ratio and associated health risk category.

Financial cost of smoking including 10-year opportunity cost at 7% return.

Track daily caffeine intake vs the 400 mg FDA guideline.

Convert step count to calories burned and distance walked.

Detailed training zones using percent-of-max or Karvonen (heart-rate reserve).

What is X% of Y, X is what % of Y, and percentage change — all in one place.

Percentage increase or decrease between two numbers.

Add, subtract, multiply, or divide two fractions and simplify the result.

Simplify a ratio or solve A:B = C:? for a missing term.

Solve A/B = C/D for the missing value.

Evaluate a math expression with +, −, ×, ÷, ^, sqrt, sin, cos, tan, log, ln, and π.

Solve ax² + bx + c = 0 for real or complex roots.

Slope, y-intercept, distance, angle, and equation of a line through two points.

Euclidean distance between two points in 2D or 3D space.

Area of common shapes: rectangle, triangle, circle, trapezoid, parallelogram, ellipse.

Mean, variance, and standard deviation (sample or population) of a dataset.

Central tendency measures for any list of numbers.

Z-score of a value in a normal distribution, plus its cumulative probability.

Union, intersection, and complement of two events (assumes independence for A ∩ B).

Compute nPr (arrangements) and nCr (selections) for two integers n and r.

Greatest common divisor and least common multiple of two integers.

Given three sides, compute area (Heron's), perimeter, all interior angles, height, and classify the triangle.

Solve a right triangle given any two of: leg a, leg b, hypotenuse c, or an acute angle.

Solve for the hypotenuse or a missing leg using c² = a² + b².

Enter any one of radius, diameter, circumference, or area — get all four.

Volume of common 3D shapes: cube, box, sphere, cylinder, cone, square pyramid, and capsule.

Total surface area of common 3D shapes: cube, box, sphere, cylinder, and cone.

Raise a base to any exponent — negative, fractional, or large — with scientific notation for extremes.

Compute log_b(x) for any positive base — 10, e (natural), 2, or a custom base.

Compute the nth root of any number — square root, cube root, or any real n.

Round a number to a decimal place or to the nearest ten, hundred, thousand — with floor and ceiling too.

Convert a decimal to scientific notation (m × 10ⁿ) and e-notation, or parse a scientific string back.

Exact arithmetic on very large integers using BigInt — beyond regular double-precision limits.

Compare an observed value to a true value and get percent error plus absolute error.

Mean, sum, count, min, max, and geometric mean for any list of numbers.

Add, subtract, multiply, transpose, or find the determinant of 2×2 or 3×3 matrices.

Convert between decimal and binary or perform binary arithmetic (add, subtract, multiply).

Convert freely between hexadecimal, decimal, and binary.

Compute a confidence interval for a sample mean using the z-distribution.

Find the sample size needed for a survey given confidence, margin of error, and expected proportion.

Convert a z-score to a p-value for one- or two-tailed tests with significance verdict.

Factor any integer up to 10¹² into its prime components with exponents.

List every positive divisor of an integer plus divisor count, sum, and perfect-number check.

Solve for remaining quantity, half-life, or elapsed time in exponential decay.

Find the GCF and LCM of any list of integers, plus a simplified ratio for the first two.

Divide integers to get quotient, remainder, mixed-number form, and decimal expansion.

Generate a strong deterministic password with configurable length, character sets, and entropy readout.

Exact age in years, months, and days between two dates.

Days, weeks, months, and years between two dates.

Find the date N days, weeks, months, or years from any date.

Duration between two times of day, in hours and minutes.

Days remaining until a target date.

Convert a time between two UTC offsets and see whether the date shifts.

Weekday, ISO week number, day of the year, and days remaining for any date.

Business days (Mon–Fri) between two dates, plus weekends and total weeks.

Volume of concrete needed for a slab, plus 10% waste allowance.

Liters of paint required, allowing for coats and coverage.

How many tiles you need for an area, with waste allowance.

Convert roof pitch (rise/run) to angle in degrees and slope percent.

Compute board feet of lumber for pricing and take-offs.

Riser count, tread run, stringer length, and stair angle from total rise.

Volume, tonnage, and bag count for a gravel area — with a 10% waste allowance.

Volume and 50 L bag count for mulching a garden bed at a chosen depth.

Sand tonnage and 25 kg bag count for a fill area at your chosen depth.

Area in ft², m², and acres for common shapes — plus a cost estimate.

Cost of fuel for a trip based on distance, efficiency, and price.

Convert between miles-per-gallon and liters-per-100km.

How long a trip will take at a steady speed.

Overall diameter, sidewall height, circumference and revolutions per mile from a metric tire spec (e.g. 225/45R17).

Gear ratio from driven and drive tooth counts, output RPM, and torque multiplication.

Total engine displacement from bore, stroke, and cylinder count in cc, liters, and cubic inches.

Vehicle speed at a given engine RPM using transmission and final-drive ratios plus tire diameter.

Solve for density, mass, or volume from the other two using ρ = m / V.

Newton's second law solver — find force, mass, or acceleration from the other two.

Solve for average speed, distance, or time using the classic v = d / t relationship.

Change in velocity over time — plus distance covered and g-force equivalent.

Solve for voltage, current, or resistance from the other two — plus the resulting power draw.

Wire voltage drop from resistivity, length, current, and AWG cross-section — with a % check against 120 V and 230 V.

Decode a 4-band resistor from band 1, band 2, multiplier, and tolerance colors.

Horsepower from torque + RPM, kW conversion, or estimated from vehicle weight and quarter-mile time.

Perceived temperature from air temperature and wind speed using the North American formula.

Perceived temperature from heat and humidity using the Rothfusz regression.

Dew point temperature from air temperature and relative humidity (Magnus formula).

Translational kinetic energy from mass and velocity, with common unit equivalents.

Sale price after a percentage or fixed discount.

Grade point average from letter grades and credit hours (US 4.0 scale).

What score do I need on the final to hit a target grade?

Compute worked hours between start and end times, minus a break — with decimal total.

Add or subtract hours, minutes, and seconds — or find the difference between two times.

Best bedtime or wake time based on 90-minute sleep cycles.

Estimate password entropy and time to crack under a plausible attack.

Cryptographically-random integer in a range.

Deterministic dice roller for any common die — reproducible, with totals and range.

Convert between US Men, US Women, EU, and UK shoe sizes using foot length.

Convert ring inner diameter or circumference to US, UK, and EU sizes.

Cost to run an appliance — kWh used plus monthly and yearly projections.