Does It Add Up?
Free calculators for money, health, and everyday math — with the honest context behind the number.
98 calculators— run— visitorsfree, no sign-up
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Money
- Bill SplitterSplit any bill fairly — with or without tip.
- Budget Leak FinderSee which categories are bleeding past your targets using the 50/30/20 rule.
- Budget SanityIs your budget realistic? The 50/30/20 rule check.
- College Degree ROIDoes your degree pay for itself? Find out.
- Compound InterestWatch your money grow with compound interest.
- Debt PayoffSee exactly when you'll be free — and how much extra payments save in interest.
- Electricity CostWhat does leaving devices on really cost you?
- Freelance RateWhat should you charge per hour as a freelancer?
- Gas CostRoad trip or commute — how much will gas cost?
- If You'd InvestedWhat if you'd invested that money instead?
- Inflation CalculatorHow much is $1,000 from 1990 worth today?
- Is This Worth It?Enter a price. See it in hours worked, coffees, and future investment value.
- Loan CalculatorMonthly payment and total cost for any loan.
- Markup / MarginCalculate price markup and profit margin.
- Mortgage CalculatorMonthly payment, total interest, and the real cost of a home loan.
- Net WorthAssets minus liabilities — your financial snapshot.
- Opportunity CostSkip one coffee a day and see what it adds up to in 20 years — visualize the cost of small habits.
- Percentage CalculatorX% of Y, what % is X of Y, percent change — all three modes.
- Retirement SavingsAre you on track to retire? How much do you need?
- Salary CalculatorConvert hourly ↔ annual ↔ monthly salary instantly.
- Savings GoalHow long to save for something? How much per month?
- Subscription TrackerTrack every subscription. See yearly damage, unused waste, and what you'd gain by cutting.
- Tax BracketFind your federal tax bracket and effective tax rate.
- Tip CalculatorSplit the bill and calculate the tip.
- Unit PriceCompare the true cost per unit when shopping.
- Work Hours CostHow many hours of work does that purchase cost you?
Life & Health
- Age CalculatorExact age, days until birthday, days lived.
- Bed SizesStandard mattress dimensions for US, UK, and EU — plus a room fit calculator.
- BMI CalculatorBody Mass Index — with context beyond the number.
- Body Fat %Estimate body fat percentage with the Navy method.
- Coffee CostWhat your daily habit really costs — and what it could become.
- Date DifferenceDays, weeks, months between two dates.
- Life in WeeksA visual of your entire life — one box per week.
- Running PacePace, speed, and finish time for your run.
- Sleep CalculatorBest times to wake up based on sleep cycles.
- Solar SavingsDoes solar make financial sense for your home?
- TDEE / CaloriesYour Total Daily Energy Expenditure — how many calories you burn.
- Time Saved CalculatorSave minutes a day — see how many work weeks that adds up to over a year.
Home & Construction
- Concrete Bags CalculatorHow many bags of concrete for your slab, footing, or post holes?
- Concrete CalculatorSlab, footing, or post holes → cubic yards and bag count.
- Construction Measurement CalculatorAdd, subtract, or multiply feet-inches-fractions the way trades work.
- Drywall Sheets CalculatorHow many sheets of drywall for a room?
- Flooring Boxes CalculatorHow many boxes of flooring to buy for your room?
- Flooring CalculatorRoom area + waste factor → boxes of flooring or square yards of carpet.
- Mulch Bags CalculatorHow many bags of mulch to cover your beds?
- Paint CalculatorRoom dimensions → gallons needed, with surface type and coats.
- Paint Cans CalculatorHow many gallons or cans of paint do you need?
- Roofing CalculatorRoof footprint + pitch → actual area, squares, and shingle bundles.
Math
- Aspect RatioGiven width or height, find the other dimension for 16:9, 4:3, golden, A-paper and more.
- Basic CalculatorThe classic — clean and fast. Add, subtract, multiply, divide and percentages.
- Fibonacci SpiralStep through the sequence and watch the golden spiral emerge — one square at a time.
- Golden RatioGiven a, b, or c — solve a + b = c where b/a = φ (1.618…).
- Golden RectangleEnter rectangle dimensions — find the golden cut that splits it into a square and a smaller golden rectangle.
- Graphing CalculatorPlot equations and visualize functions.
- Metallic RatiosGolden, silver, bronze and all metallic means — solve a + b = c where b/a = Mₙ.
- Musical IntervalFrequency ratios for any musical interval — equal temperament vs just intonation, in cents.
- Normal DistributionThe bell curve — adjust mean and standard deviation, see the 68-95-99.7 rule live.
- Number Base ConverterConvert between binary, octal, decimal, and hex. Type in any field — all others update live.
- Proportion SolverSolve a/b = c/d for any missing value using cross-multiplication.
- Pythagorean TheoremDrag the legs — watch the squares animate and a² + b² = c² update live.
- Quadratic FormulaSolve ax² + bx + c = 0. Shows discriminant, step-by-step working, and real or complex roots.
- Scientific CalculatorTrig, logs, exponents — the full toolkit.
- Sieve of EratosthenesWatch the ancient algorithm find every prime up to 120 by crossing out multiples.
- Sine Wave ExplorerAdjust amplitude, frequency, and phase — watch the wave reshape in real time.
- Unit CircleInteractive unit circle with all trig values.
Scores
- Does It Add Up? Life ScoreScore your money, health, and time — all in one number.
- Financial Health ScoreScore your financial foundation across five dimensions.
- Is This a Good Deal?Score a sale from 1–10 before you buy it.
- Job Offer ComparisonCompare two offers on total value, not just salary.
- Should I Refinance?Clear yes/no/wait recommendation with break-even math shown.
Sizing
- Bra Size CalculatorBand + bust measurement → bra size in US, UK, and EU with the math explained.
- Clothing Size ConverterConvert US, UK, and EU clothing sizes for men's and women's apparel.
- Kids' Shoe Size ConverterFind children's shoe sizes by age, foot length, or known size — US, UK, EU.
- Ring Size CalculatorFinger measurement → ring size in US, UK, and EU. Works from circumference, diameter, or known size.
- Shoe Size ConverterEnter any shoe size — get US Men's, US Women's, UK, EU, and CM equivalents.
Maker
- ISO Paper SizesA0–A10, B-series, and C-series envelope dimensions in mm, cm, and inches.
- Recipe ScalerScale any recipe up or down to any serving size.
- Resistor Color CodeDecode 4-band or 5-band resistor color codes, or find the bands for any resistance value.
- Square FootageCalculate the square footage of any room or space.
- Tile CalculatorHow many tiles do you need? Including waste factor.
Utilities
- Cloud Hosting Cost CalculatorCompare what your server setup costs per month on Hetzner, Vultr, Linode, DigitalOcean and AWS Lightsail.
- Countdown TimerCount down to any date or event.
- Fraction CalculatorAdd, subtract, multiply, divide fractions.
- GPA CalculatorCalculate your GPA from grades and credit hours.
- Ohm's LawVoltage, current, resistance, power — solve for any one.
- Password StrengthHow strong is your password? And how long to crack?
- QR CodeGenerate a QR code for any URL or text.
- Random PickerPick randomly from a list — names, options, decisions.
- StatisticsMean, median, mode, standard deviation for a data set.
- StopwatchSimple stopwatch with lap times.
- Text DiffCompare two blocks of text and highlight differences.
- Unit ConverterLength, weight, temperature, volume — convert anything.
Games & Fun
- Add to 10Math speed game — how fast can you add to 10?
- Crossword HelperStuck on a clue? Find words that fit the pattern.
- Dice RollerRoll any combination of dice — d4 to d100.
- Lottery OddsExactly how unlikely is winning the lottery?
- Mad LibsFill in the blanks, then generate a hilariously unpredictable story.
- Magic 8-BallAsk a question. Receive wisdom — one of 20 classic answers, picked at random.