Split a restaurant bill
Share one meal bill equally, including an additional service charge. Use the settlement tool instead when people ate different amounts or paid in advance.
Start here for whatever you need to calculate.
Search using an everyday question or a formula name. You do not need to know the category first.
Find it by what it does, even without knowing its name.
- To see where your money goes, search for monthly balance or openMonthly budget。
- To scale a recipe from four to six servings, search for recipe or openScale recipe quantities。
- To group whole numbers or find a shared cycle, openGreatest common divisor and least common multiple; for fraction arithmetic, useFractions and decimal conversion。
- To count selections from a group, openCombinations and permutations to distinguish selections from ordered arrangements.
- To see how spread out a set of numbers is, openStandard deviation and variance and compare sample and population results together.
- To calculate savings at 80% of the original price, search for discount or openDiscounted price。
Check the units and assumptions before entering your own data. Save separate plans to compare different conditions. Export a backup before changing devices.
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Monthly budget
See how much of your monthly income remains after living costs. Compare that remainder with the amount you want to save.
Coupons and cashback
Separate what you pay now from rewards you may receive later. Choose one discount or two successive discounts with a cashback cap.
Subscription cost
Compare monthly, quarterly and annual subscriptions on the same monthly basis. You can also divide an average cost among several people.
Working days and business dates
Count working days between dates or find a date after adding working days. Choose a manual Monday-to-Friday calendar or the covered Taiwan government calendar.
Volume and scientific units
Convert volume, pressure, energy or speed within the same physical quantity. Select the quantity first, then choose both units again.
Percentage change
Find how much a positive starting value increased or decreased. Use the same measurement unit for both entries.
Appliance electricity cost
Estimate one appliance's energy cost using your own power and tariff assumptions. Enter average operating power rather than assuming rated maximum power is used continuously.
Savings target projection
Compare a future savings target with your starting money and monthly contributions. See both nominal money and purchasing power under your assumptions.
Savings goals
Plan monthly saving for one goal or several household goals. Allocate each existing amount to just one goal.
Investment profit and loss
Calculate a completed or hypothetical trade's net gain after entered costs. Enter the actual number of shares or asset units.
Compound annual growth rate
Express a change in investment value as an equivalent compounded annual rate. Use this for a holding without intermediate deposits or withdrawals.
Loan payment and early repayment
Estimate a fixed-rate loan's equal monthly payment. The optional prepayment mode shows how extra principal can shorten the loan term.
Goal completion
Compare how much you have completed with a total target. The two amounts must measure the same thing.
Discounted price
Find a sale price from a price multiplier, or work backwards from an actual item payment. The multiplier follows the Taiwan out-of-ten discount notation.
Compare unit prices
Compare package offers using the same weight, volume or item unit. Enter the complete promotional set rather than the price of just one package.
Group expense settlement
Settle shared expenses when people paid different amounts or have different shares. Choose either each person's total paid or an itemized expense list.
Calendar days and date offsets
Find the calendar-day gap between two dates and a separate date obtained by adding or subtracting days. Weekends remain part of the calendar count.
Age on a date
Find completed age on any selected date. You do not have to use today as the reference date.
Time between local dates
Subtract two local date-times within the same time zone. Include the date when a journey crosses midnight.
Working time
Calculate time worked after subtracting unpaid or excluded breaks. Enter full dates and times for overnight shifts.
Length conversion
Convert a measured length between metric and customary units. Keep the same physical dimension when comparing a space with furniture.
Area and Taiwan ping
Convert area between square metres, square feet and Taiwan ping. This is an area conversion rather than a judgement about property records.
Weight conversion
Convert metric and customary weight units, including Taiwan jin and liang. Choose units explicitly to avoid regional naming differences.
Temperature conversion
Convert a temperature between Celsius, Fahrenheit and kelvin. Select the original scale before entering the reading.
Tax-inclusive and pre-tax price
Convert a quoted price between tax-inclusive and pre-tax amounts. Select whether the entered amount already includes the tax.
Adult BMI
Calculate adult body mass index from height and weight. Enter centimetres and kilograms rather than metres or pounds.
Running pace and finish time
Estimate duration from pace or calculate average pace from duration. Choose the direction first so only the relevant time input is used.
Scale recipe quantities
Scale an ingredient list by servings or by the amount of one ingredient available. Select a reference ingredient from your list when working backwards.
Floor and wall area
Estimate rectangular floor area and the surrounding wall area. Measure all lengths in metres.
Appliance energy use
Estimate electricity consumed by one appliance over a period. Use realistic average power when the appliance cycles on and off.
Trip fuel cost
Estimate fuel needed and fuel cost for a route. Enter the complete trip distance, including the return journey if relevant.
Fractions and decimal conversion
Add, subtract, multiply or divide two fractions, or convert finite decimals and mixed numbers. Choose a mode before entering its values.
Gross margin and markup
Distinguish gross margin from markup when comparing a selling price with product cost. Both percentages use the same profit but different denominators.
Moving-in cash budget
Estimate how much cash you need before moving into a rented home. Include both refundable cash tied up and expenses you expect to spend.
Travel budget and saving plan
Combine a trip budget and the monthly amount still to save. Optional foreign-currency mode adds a separately entered foreign expense.
Car running-cost budget
Combine recurring vehicle costs into monthly and annual budgets. Choose petrol or electric operation while keeping the other fixed costs.
Effective hourly earnings
Compare take-home earnings with all the time and money needed to do the job. Include commuting and additional work-related time.
Freelance project quote
Build a quote from the time and direct costs a project requires. Set aside hours for revisions and administration rather than hiding them.
Monthly pet budget
Plan regular pet expenses and a separate emergency reserve. Convert annual charges into monthly provisions.
Prime factorization calculator
Break one positive whole number into prime factors, see repeated factors as powers, and follow every exact division step.
Steps and walking distance
Convert step counts and walking distance, or measure your own average step length. Each foot landing counts as one step, rather than a two-step stride.
Recipe ingredient cost
Allocate the cost of ingredients actually used in a recipe. Enter each package price, total package quantity and the quantity used.
Screen pixel density and size
Estimate a rectangular screen's pixel density and visible width and height. Use the physical visible diagonal and the product's native resolution.
Inventory reorder point
Find an inventory threshold for reviewing replenishment of one product. Keep stock on hand, incoming orders and backorders separate.
EV charging time and cost
Estimate energy, charging time and electricity cost between two battery levels. Use average input power and efficiency on the same billed or metered side.
Ex-dividend reference price
Estimate a theoretical reference price after cash dividends and free bonus shares. Enter the number of shares held rather than stock lots.
Rent or buy cost comparison
Compare nominal renting cost with buying and selling a home over the same period. State your own resale assumption rather than treating it as a prediction.
Retirement withdrawals and asset duration
Estimate how long assets can cover spending after a fixed income. Compare beginning-of-month and end-of-month withdrawal timing.
Compare debt repayment order
Compare repaying smaller balances first with repaying higher-interest debts first. Enter each debt on a separate line, using amounts in one currency.
Premature infant corrected age
Calculate an educational corrected-age reference for a child born early. Enter completed pregnancy weeks and the extra days separately.
Cake tin and recipe scaling
Scale an ingredient amount by the relative filled volume of two straight-sided tins. Measure the intended batter fill height, not just the tin's outer height.
Mix beverage concentrations by mass
Find how much of two beverage mixtures to combine for a target mass concentration. All concentrations must describe the same dissolved substance.
Tiles and whole boxes
Estimate tile pieces and whole boxes for a measured area. Choose a waste allowance for your own layout.
Wallpaper rolls and pattern repeat
Estimate strips and rolls for walls of the same height. Include trimming and an optional straight-match vertical repeat.
Simple investment payback
Find when cumulative undiscounted cash inflows first recover an initial investment. Enter each period's net cash flow in order, including negative flows.
Taiwan overtime pay estimate
Estimate additional overtime pay under Taiwan's general monthly-paid Labor Standards Act framework. This scope assumes normal work of eight hours daily and 40 hours weekly.
Taiwan annual leave entitlement
Estimate statutory annual leave under Taiwan's Labor Standards Act anniversary system. Use continuous service and the leave used within the current entitlement period.
Tyre dimensions and speed change
Compare the geometric outside diameters of two tyre sizes. Estimate the speed change from the new-to-old diameter ratio.
Parcel dimensional and billed weight
Compare a parcel's actual and dimensional weights before billing-weight rounding. Use the packed outer dimensions and confirmed carrier rules.
Adult resting energy estimate
Estimate resting energy expenditure using the Mifflin-St Jeor equation. Select the coefficient group used by the original research rather than interpreting it as a health judgement.
Waist-to-hip and waist-to-height ratios
Calculate two ratios from body measurements in the same unit. Measure carefully rather than treating a ratio as a diagnosis.
Estimated exercise heart-rate range
Estimate a heart-rate interval from age and measured resting heart rate. Intensity here is a percentage of heart-rate reserve, not maximum heart rate.
Two linear equations
Solve equations arranged as a*x + b*y = c and d*x + e*y = f. Enter the six numbers, including minus signs, rather than pasting whole equations.
Arithmetic and geometric sequences
Find a final term and sum for an arithmetic or geometric sequence. Choose whether you repeatedly add a difference or multiply by a ratio.
Return on dated cash flows
Estimate an annualized return when investment and recovery dates are irregular. Enter money invested as negative and money received as positive.
Due date and pregnancy weeks
Estimate a due date and pregnancy weeks from a known reference. Choose the first day of the last menstrual period or a clinician-confirmed due date.
Baker percentages and dough weight
Build a dough formula from total weight and baker percentages. Flour is the 100% reference, rather than the entire dough.
Paint litres and whole cans
Estimate paint volume and whole cans for one product. Calculate primer and topcoat separately when their coverage differs.
Break-even unit sales
Estimate how many units of one product must sell to cover fixed costs. Use the same accounting period for all fixed costs.
Flight duration across time zones
Find elapsed time using each endpoint's local clock and selected city time zone. Change the arrival date when a flight crosses a calendar day.
Activity energy estimate
Estimate activity energy using a MET value matched to the activity source. MET describes an activity's metabolic intensity, not its speed.
Weighted average, GPA and target score
Average values using their weights, or calculate stock purchase cost, a school-defined GPA or a remaining exam target. Choose the mode before preparing each line.
Combinations and permutations
Count selections when order does or does not matter. Objects must be distinct and cannot be selected more than once.
Standard deviation and variance
Describe how spread out a list of numbers is around its mean. Both sample and population statistics are shown.
Greatest common divisor and least common multiple
Find the largest integer dividing both numbers and the smallest positive multiple shared by them. These answer different grouping and cycle questions.
Child-raising budget
Plan future child-raising costs by age stage, with an optional separate estimate of income lost during leave. Replace every example with your household's assumptions.
University living-cost budget
Separate tuition, accommodation and other living costs across university years. Housing months may differ from the months spent on campus.
Future lifetime living costs
Estimate future living spending from your current age to a chosen birthday. Compare different living-cost and retirement assumptions.
Pythagorean theorem
Find a missing side in a right triangle. Choose whether the missing side is the longest hypotenuse or one of the two perpendicular legs.
Trigonometric functions
Calculate sine, cosine and tangent or recover a principal angle from a function value. Check degrees versus radians before calculating.
Quadratic equation
Solve a quadratic arranged as a*x^2 + b*x + c = 0. Move all terms to the left before entering the coefficients.
Powers and roots
Raise a number to a power or find its nth root. Select the operation before entering the exponent or root degree.
Logarithm
Find the exponent needed to raise a base to a positive number. This is different from dividing the number by the base.
Common shape areas
Calculate triangle, rectangle or circle area from the dimensions for that shape. Keep all lengths in the same unit.
Common solid volumes
Calculate the volume of a rectangular box, cylinder or sphere. Enter the dimensions shown for the chosen solid.