All calculators
Every tool on Chalk Calculator, grouped by what it is for. 77 calculators, all free, all running entirely in your browser.
Money
About this categoryWork out what a loan really costs, how savings compound, and what a long-term plan could be worth. Every projection shows the assumptions behind it.
- Amortization ScheduleEvery payment on a loan, month by month, with dates and the interest crossover.
- Loan PaymentMonthly payment, total interest and a full amortization schedule.
- Debt SnowballPay off several debts in order, and see what snowball costs against avalanche.
- Credit Card PayoffHow long a card takes to clear, and what paying only the minimum really costs.
- Personal LoanPayment and true cost of a personal loan, including origination fees.
- Savings GoalWhat to put away each month to hit a target, or how long it will take.
- Break-EvenHow many units cover your fixed costs, and what happens if you sell fewer.
- Compound InterestGrowth of a balance with regular contributions and any compounding frequency.
- Investment GrowthProject a portfolio with contributions, fees and inflation applied.
- 401(k)What contributing really costs your paycheck, and whether you are leaving employer match behind.
- RetirementSavings at retirement, what it supports in income, and any shortfall.
- Roth IRARoth growth, contribution limit and whether your income phases you out.
- InflationWhat an amount is worth in another year, using official CPI data.
- Markup & MarginThe two numbers people confuse, and what the confusion costs per sale.
- ROIReturn on investment as a total percentage and an annualized rate.
- Income TaxYour 2026 federal income tax, bracket by bracket, with the new tips, overtime and senior deductions.
- Capital Gains TaxFederal tax on selling stocks, funds or other investments in 2026 — at 0%, 15% or 20% — with losses netted.
- Interest RateThe interest rate a loan is charging, worked out from the amount, the monthly payment and the term.
- Debt-to-IncomeWork out your front-end and back-end debt-to-income ratios and see how they compare with FHA and conventional mortgage limits.
- Wedding BudgetSplit a wedding budget across venue, catering, photography and nine more categories, in the proportions real couples spent in 2025.
- Cost of a ChildUSDA’s estimate of what it costs to raise a child to 18, by income and family size and category by category, in today’s dollars.
Work & Pay
About this categoryTurn hours into pay and pay into take-home. Tax figures come from the published IRS tables for the year you select, and the assumptions are listed on every page.
- Time CardAdd up clock-in and clock-out times, subtract breaks, and get weekly hours and gross pay.
- PaycheckEstimate take-home pay after federal tax, Social Security, Medicare and deductions.
- SalaryConvert pay between hourly, weekly, biweekly, monthly and annual.
- Hours BetweenHow long between two times, including overnight — in hours and minutes and in decimal.
- OvertimeWork out overtime pay at time-and-a-half, double time, or a daily overtime rule.
- CommissionFlat or tiered commission, with tiers treated the way they actually work.
- Annual IncomeTotal up income from several sources into one yearly figure.
- Self-Employment TaxSocial Security and Medicare on freelance or business profit, with any W-2 wages taken into account.
From what you can afford to how much gravel fills the driveway. Material estimates state their density and waste assumptions so you can adjust them for your job.
- Home AffordabilitySee both the maximum price a lender may allow and the price that stays comfortable.
- Refinance Break-EvenWhen refinancing pays for itself — and whether it actually costs you more.
- Mortgage PayoffSee how much time and interest extra payments take off your mortgage.
- Mortgage PaymentMonthly principal, interest, taxes, insurance, HOA and PMI in one figure.
- RoofingRoof area, squares and shingle bundles from footprint and pitch.
- MulchBags or cubic yards of mulch for a bed, with the depth guidance that decides the order.
- GravelCubic yards and tons of gravel for a driveway, path or pad.
- Square FootageArea of rectangles, circles, triangles and multi-room layouts.
- PaintGallons of paint for walls and ceilings, minus doors and windows.
- TileTiles for a floor or wall, counting the grout joint and the waste your layout actually needs.
- DrywallSheets for a room, plus the joint compound, tape and screws people forget to buy.
- FlooringBoxes of flooring needed, including waste for cuts and pattern.
- ConcreteCubic yards of concrete for slabs, footings, columns and tubes.
- Rent vs BuyCompare renting with buying over the years you would stay, with every cost and assumption shown and a break-even year.
What a car costs to buy, finance and run — including the comfortable-payment view, not just the maximum a lender would approve.
- Car AffordabilityThe car price that fits your budget, not just the loan you could get approved for.
- Fuel CostWhat a trip costs in gas, split between passengers if you are sharing.
- Car PaymentMonthly auto loan payment including trade-in, sales tax and fees.
- Lease vs BuyCompare the total cost of leasing against financing over the same period.
- EV ChargingCost per charge, per mile and per year, with charging losses included.
School
About this categoryWork out the grade you need, your GPA on your own school’s scale, and fractions with every step shown. Where schools differ, the calculator asks rather than assumes.
- FractionsAdd, subtract, multiply and divide fractions and mixed numbers, with every step shown.
- GPAYour term and cumulative GPA, weighted or unweighted, on the grade scale your school uses.
- Final GradeThe score you need on the final to reach the grade you want.
- Standard DeviationSample or population standard deviation, variance and mean of a list of numbers, with every step shown.
- TriangleSolve any triangle from three sides and angles: the missing sides, angles, area and perimeter.
- AreaThe area of a square, rectangle, triangle, trapezoid, parallelogram, circle or ellipse, with the formula worked through.
- VolumeVolume and surface area of a cube, box, cylinder, cone, sphere or pyramid, with the capacity in gallons or liters.
- SlopeThe slope of the line through two points as an exact fraction, with its equation, angle, grade and midpoint.
- ProportionSolve a/b = c/d for the missing value with cross-multiplication shown, or check whether two ratios are equal.
- Pythagorean TheoremThe missing side of a right triangle from the other two, with the exact square root, the angles and every step.
- Mean, Median, ModeFind the mean, median, mode and range of a list of numbers, with the values sorted and every step shown.
- LCM & GCFFind the least common multiple and greatest common factor of two or more numbers, with each prime factorization shown.
- Long DivisionDivide step by step, the way it is done on paper, with the remainder, the decimal, and where the decimal starts repeating.
- Quadratic FormulaSolve ax² + bx + c = 0 with the discriminant and every substitution shown, and exact roots in simplest radical form.
- Scientific NotationConvert to and from scientific and E notation, or add, subtract, multiply and divide, with significant figures kept.
Everyday
About this categorySmall calculations you need in the moment, built to open fast and answer immediately on a phone.
- DiscountSale price after one discount or several — which do not add up the way people expect.
- TipTip, total and an even split per person — with rounding options.
- Sales TaxAdd sales tax to a price, or work backwards from a total to find the tax.
- Date DifferenceDays between two dates, in days, weeks, months and working days.
- AgeExact age in years, months and days, plus the countdown to the next birthday.
- PercentageEvery common percentage question in one place, including change and reverse.
- BMIBody mass index in either unit system, with what it can and cannot tell you.
- PacePace, time or distance for running, walking and cycling, with split times.
- Electricity CostWhat an appliance costs to run, including the standby draw people forget.
- Download TimeHow long a file takes at a given speed, with bits and bytes handled correctly.
- TimeAdd and subtract hours, minutes and seconds, and see what time it will be after.
- CaloriesEstimate how many calories you need a day from your age, height, weight and activity, with your BMR and an optional macro split.
- Dog AgeConvert your dog’s age to human years three ways side by side: the AVMA guideline, the UC San Diego DNA formula and the 7× rule.
- Due DateEstimate your due date from the first day of your last period, with weeks pregnant and the dates of early, full and late term.