156 free tools · no signup
GPA, age, statistics, money, health and game calculators — built for students, parents, investors and makers. Everything runs in your browser — no account, no download.
Ready to use
These tools are ready to use — click and get your result instantly. Every page works perfectly on mobile and keeps working offline once the page has loaded.
Convert a percentage to the 4.0 GPA scale and a letter grade — with a conversion table.
Open calculator → Mean, Median, Mode CalculatorAverage, median, mode and range in one click, with full step-by-step working.
Open calculator → Coefficient of Variation CalculatorFind relative variability from the mean, standard deviation and CV%.
Open calculator → Decimal to Inches CalculatorConvert a decimal like 0.4375 to the nearest 1/16, 1/32 or 1/64 fraction.
Open calculator → Compound Interest with WithdrawalsFinal balance, interest and a year-by-year chart, with monthly withdrawals included.
Open calculator →All 8 families
Each family has its own hub page listing all its calculators with volume, formula and examples. Pick your category below.
GPA from percentage, high school and middle school GPA, weighted GPA, grade calculator with weights, AP score tools.
Explore education calculators →
Paycheck and income tax by state, child support calculator, VA disability rating, loans and compound interest.
Explore finance calculators →
Army body fat, calories burned walking, treadmill and pace calculators, 1RM bench press, military PT tests.
Explore health & fitness calculators →
17 toolsAge calculator for child and baby, IVF due date, conception calculator, pregnancy and baby growth tools.
Explore family & life calculators →
23 toolsMean median mode, standard deviation, coefficient of variation, t critical value, triangles, decimal to inches.
Explore math & stats calculators →
12 toolsElden Ring build and level calculators, Palworld breeding, CS2 trade up, D&D 5e point buy, fantasy points.
Explore games calculators →
21 toolsBoard and batten, metal roof and gutter cost, blown-in insulation, concrete, 0-60 time, tire size.
Explore home & auto calculators →
13 toolsSun moon rising sign, Vedic birth chart, snow day predictor, dog due date, tip and discount tools.
Explore more calculators →
Statistics & math
Mean, median, mode, standard deviation, coefficient of variation, mean absolute deviation, t and f critical values — every tool shows step-by-step working, not just the final answer.
On the math side: right triangle and special right triangle solvers, a net ionic equation balancer, the combined gas law, percentage change and a decimal to inches converter for woodworking.
Money & benefits
Child support is not based on one generic formula — every state has its own guidelines. That is why Florida, California, Indiana, Pennsylvania, Arkansas, Ohio, Virginia and Nevada each have their own page.
You will also find paycheck and income tax by state, sales tax and reverse sales tax, car sales tax, tag title tax, VA combined rating and VA back pay, loan payments, APR/APY and savings bonds.
Why CalcKit
No popups, no login walls, no slow loads. Just open a tool and get to work.
Every calculation runs in your browser. No server round-trip, no waiting spinner.
Your numbers are never uploaded. Close the page and the data is gone — no tracking.
No account, no email, no trial. The site is supported by ads, and the tools are always free.
iPhone, Android, tablet or desktop — the layout stays clean on every screen.
4.0 GPA scale, sample standard deviation, state child support guidelines, official military tables.
Not just the answer — steps, formulas and conversion tables too, so you can verify every result.
Everything in one place
Eight families, 156 calculators live today — pick one and jump straight into the tool itself. Every link below opens a working calculator, not a category page.
The GPA calculator converts your percentage into a 4.0 scale GPA and a letter grade in one step. Use the high school GPA calculator for a weighted 4.0 scale with honors and AP classes, or the middle school GPA calculator when your school does not use credits. A grade calculator with weights works out the score you need on the final exam to hit your target grade.
The child age calculator and baby age calculator give exact years, months, weeks and days from a date of birth, plus the next birthday countdown. For expecting parents there is an IVF due date calculator based on transfer date, a conception calculator, and a tool that answers when did I get pregnant from your last period or due date.
The one rep max calculator estimates your max lift from a lighter set, the army body fat calculator follows the current Army standard, and the Air Force PT calculator scores push-ups, sit-ups and the 1.5 mile run against the published standard.
The board and batten calculator works out board count, spacing and material cost per wall, and the 0-60 calculator turns a timed run into a 0 to 60 mph time. More home improvement and auto tools are being built next.
The Palworld breeding calculator shows parent pairs and inheritance chances, the D&D 5e point buy calculator spends your 27 points and shows modifiers, the Elden Ring build calculator plans stats and runes, and the CS2 trade up calculator works out expected profit from a trade-up contract.
Work out federal income tax for a single filer, then add the state layer with the California income tax calculator or the NYC income tax calculator. Parents can estimate Florida child support or California child support, veterans can estimate VA back pay, and buyers can estimate closing costs before they sign.
The mean, median, mode calculator works out all three averages from one list of numbers, the standard deviation calculator shows every step of the calculation, the right triangle calculator solves for missing sides and angles, and the decimal to inches calculator converts decimals to fractions like 7/16″.
The Sun, Moon & Rising sign calculator finds your big three from your birth date, time and place — and if your birthplace is not in the list, you can add your own. More everyday calculators, like date, tip and discount tools, are on the way.
How it works
Every calculator follows the same flow — that is why 156 tools are easy to use on one site.
Use the search bar, a category card or a footer link — three ways to reach the tool you need.
Fields are clearly labelled (percentage, dates, weights, state). No hidden settings.
Along with the final answer you also get the formula and a table, so you can verify it yourself.
FAQ
The questions we get asked most often.
Yes. Every calculator on CalcKit is free and there is no paywall, trial or download. The site is supported by advertising, so you can run as many GPA, age, statistics or finance calculations as you like.
No account, no email and no sign-up. All calculations run in your browser, so your numbers never leave your device unless you choose to share a result.
The GPA calculator converts any percentage into the standard 4.0 GPA scale and a matching letter grade, then shows the conversion table so you can check each step. It is useful for students applying from percentage-based systems such as Pakistan, India, Bangladesh, Nigeria and the UK.
Yes. The education section covers a GPA calculator from percentage, a high school GPA calculator, a middle school GPA calculator with and without credits, a weighted GPA calculator, GPA with AP classes, and a grade calculator with weights for final and semester grades.
Yes. State-specific pages cover child support for Florida, California, Indiana, Pennsylvania, Arkansas, Ohio, Virginia and Nevada, paycheck and income tax for California, New York, Michigan, Washington and New Jersey, plus sales tax and car sales tax by state.
Yes. Every page is mobile-first and the calculators themselves have no external dependencies, so the tools work on iPhone, Android, tablet and desktop, even offline once the page has loaded.
Every tool uses the standard published formula for that calculation — the 4.0 GPA scale, the sample standard deviation formula, state child support guidelines and official military body fat tables. Results are estimates for guidance; for legal, medical or tax decisions always confirm with a professional.
Tell us which tool you need — we build the most-searched calculators first, and your request goes into the queue.
CalcKit