Date Duration Calculator
Calculate the exact time difference between two dates, in years, months, days, weeks, hours, minutes, and seconds.
Use CalculatorAge Calculator
Calculate your age in years, months, and days based on your birth date.
Use CalculatorDog Age Calculator
Convert your dog's age to human years, and calculate their age in dog years.
Use CalculatorTime Duration Calculator
Calculate the duration between two specific times, including hours, minutes, and seconds.
Use CalculatorTime to Decimal Calculator
Convert days, hours, minutes, and seconds into a single decimal value for easy calculations.
Use CalculatorWork Hours Calculator
Calculate total work hours, including breaks and overtime, for your timesheet.
Use Calculator3-Digits Stopwatch
A precise stopwatch with millisecond accuracy, perfect for timing events in games, sports, and daily tasks.
Use CalculatorHijri Date to Gregorian Converter
Convert dates from the Islamic Hijri calendar to the Gregorian calendar.
Use CalculatorHijri Date Converter
Convert dates from Gregorian to Hijri and vice versa, supporting various Islamic calendar standards.
Use CalculatorDays Between Two Dates Calculator
Calculate the number of days between two specified dates quickly and accurately.
Use CalculatorDate Add Subtract Calculator
Add or subtract days, months, or years from a given date to find a future or past date.
Use CalculatorDate Calculator
Perform various calculations involving dates, such as adding or subtracting days, and finding the day of the week.
Use CalculatorReading Time Calculator
Estimate how long a book or article takes from word count or pages, your reading speed (WPM), and optional daily minutes to see days to finish.
Use CalculatorSleep Cycle Calculator
Rough wake-time targets from bedtime, or bed-time ideas from your alarm, using adjustable cycle length (often 90 minutes). Not medical advice.
Use CalculatorDuration Sum Calculator
Add many clip lengths in one go (MM:SS, H:MM:SS, or seconds per line). Great for podcasts, edits, and playlists.
Use CalculatorVertical Safe Zone Calculator
Turn top/bottom/side margin percentages into pixel insets for 9:16 vertical video (Shorts, Reels, etc.). Planning helper—not official platform specs.
Use CalculatorCat Age Calculator
Rough cat years ↔ human years using a common simplified chart. Decimal ages supported—not veterinary advice.
Use CalculatorRule of 72 Calculator
Estimate doubling time from a growth rate, or implied rate to double in N years. Educational mental math only.
Use CalculatorISO Week Number Calculator
Get ISO week number and ISO year for any calendar date (ISO 8601, week starts Monday).
Use CalculatorBusiness Days Calculator
Count Monday–Friday days between two dates (weekends only; no public holidays).
Use CalculatorNarration Time Calculator
Words plus words-per-minute to estimate voice-over or audiobook duration.
Use CalculatorKnitting Gauge Calculator
Convert stitches and rows per 10 cm ↔ per inch for pattern scaling.
Use CalculatorCrochet Hook Size Calculator
Match hook diameter in mm to common US letter / number labels (approximate chart).
Use CalculatorDPI Print Width Calculator
Pixels and DPI to print width in inches; handy for photo prints.
Use CalculatorAspect Ratio Calculator
Given width and ratio W:H, compute height (or scale both sides by a factor).
Use CalculatorVideo File Size Calculator
Bitrate and duration to estimated file size (Mbps, minutes).
Use CalculatorBandwidth Download Time Calculator
File size and download speed to approximate transfer time.
Use CalculatorWorld Clock (Two Time Zones)
Show current date and time in two IANA time zones side by side.
Use CalculatorMulti-Timezone Meeting Overlap
2–5 IANA zones, one calendar day, shared local office hours—see which UTC hour starts put everyone in-window (optional Mon–Fri).
Use CalculatorSemester Week Calculator
Week number since a semester start date (weeks aligned to Mondays).
Use CalculatorFinal Exam Grade Calculator
Weighted grades: what you need on the final to reach a target course grade.
Use CalculatorSimple GPA Calculator
Enter grade points and credits per line; computes weighted GPA on a 4.0-style scale.
Use CalculatorHourly to Annual Salary Calculator
Hourly rate × hours per week × 52 (simple, no tax).
Use CalculatorFreelance Hourly Rate Calculator
Target annual income, billable weeks/hours, and buffer % to a suggested hourly rate.
Use CalculatorCoffee Brew Ratio Calculator
Coffee grounds (g) and ratio 1:N to total brew water in ml.
Use CalculatorBaker's Percentage Calculator
Flour weight and ingredient % of flour to ingredient grams.
Use CalculatorDaily Water Intake Estimate
Body weight (kg) × 0.033 L rough estimate—not medical advice.
Use CalculatorRunning Pace Calculator
Minutes and seconds per km to km/h and approximate mile pace.
Use CalculatorRace Pace Split Calculator
Race distance and goal time → average pace per km and per-5 km cumulative splits.
Use CalculatorPaint Coverage Calculator
Wall area, coverage per gallon, and coats → gallons needed (rounded up).
Use CalculatorConcrete Slab Volume Calculator
Length × width (ft) × depth (inches) to cubic yards for a rectangular slab.
Use CalculatorTile Quantity Calculator
Room floor area, square tile size, and waste % → approximate tile count.
Use CalculatorLawn Fertilizer Bags Calculator
Lawn area and coverage per bag → number of bags (rounded up).
Use CalculatorYouTube Chapter Timestamps
Paste segment durations per line; get cumulative chapter markers for descriptions.
Use CalculatorTip Calculator
Bill amount, tip percent, and party size—tip, total with tip, and per person.
Use CalculatorBMI Calculator
Body mass index from weight (kg) and height (cm)—adult screening categories only.
Use CalculatorTrip Fuel Cost Calculator
Miles, MPG, and price per gallon—gallons used and trip fuel cost (US units).
Use CalculatorMortgage Payment Calculator
Loan amount, annual rate, and years—estimated monthly principal & interest (excludes tax/insurance).
Use CalculatorCompound Interest Calculator
Principal, annual rate, years, and compounding periods per year—future value.
Use CalculatorPercentage Change Calculator
Old value vs new value—absolute change and relative percent change.
Use CalculatorMarkup & Margin Calculator
Cost plus markup % on cost—selling price and margin % of selling price.
Use CalculatorSquare Footage Calculator
Rectangle in feet—length × width to square feet (and approximate square meters).
Use CalculatorSimple Interest Calculator
Principal, annual rate %, and years—interest and total repayment.
Use CalculatorBreak-Even Calculator
Fixed costs, variable cost per unit, and price—units needed to break even.
Use CalculatorRent Affordability Calculator
Monthly income and max rent % of income—rule-of-thumb rent cap.
Use CalculatorDecimal Odds to Implied Probability
Enter decimal odds (e.g. 2.50)—naïve implied win % (no vig removed).
Use CalculatorCredit Card Payoff Estimator
Balance, APR, and fixed monthly payment—months to payoff and total interest (simplified).
Use CalculatorCAGR Calculator
Starting value, ending value, and years—compound annual growth rate %.
Use CalculatorRetirement Savings Calculator
Monthly contribution, nominal annual return %, and years—future value and total contributed.
Use CalculatorInflation Calculator
Present value, annual inflation %, and years—future nominal value and multiplier.
Use CalculatorCar Loan Calculator
Principal, APR %, and term in months—monthly payment and total interest (amortizing).
Use CalculatorMax Loan from Payment
Affordable monthly payment, APR %, and years—estimate maximum loan principal.
Use CalculatorRandom Number Generator
Integer range, how many numbers, optional unique draws (≤ range size).
Use CalculatorFuel Efficiency Converter
US MPG ↔ liters per 100 km using a fixed conversion constant.
Use CalculatorUnit Price Calculator
Total price and quantity—cost per unit; optional second product comparison.
Use CalculatorProfit Margin Calculator
Revenue and cost—gross profit dollars and profit margin % on revenue.
Use CalculatorRoman Numeral Calculator
Convert Arabic numbers to Roman numerals and parse common Roman strings back.
Use CalculatorAge Difference Calculator
Years, months, and days between two birth dates (calendar-based).
Use CalculatorOvertime Pay Calculator
Base hourly rate plus regular and overtime hours—overtime paid at 1.5× for a rough gross total.
Use CalculatorSavings Goal (Months)
Target balance, monthly deposit, and nominal annual rate—months to reach goal (simplified).
Use CalculatorPayback Period Calculator
Upfront cost and constant yearly benefit—simple payback time in years.
Use CalculatorWind Chill Calculator
Air temperature and wind speed—approximate wind-chill index (educational).
Use CalculatorKilometers Miles Converter
Kilometers ↔ statute miles using the standard conversion constant.
Use CalculatorSplit Bill Calculator
Total bill, headcount, and optional tip percent—per person share.
Use CalculatorReverse Percentage Calculator
If a value grew by P% to reach V, find the original base before the increase.
Use CalculatorWeighted Average Calculator
Two value–weight pairs—weighted mean (e.g. grades and credits).
Use CalculatorHourly to Monthly Pay
Hourly rate × hours per week × (52÷12)—rough gross monthly (before tax).
Use CalculatorStacked Discounts
Two successive percent-off steps—final price and equivalent single discount.
Use CalculatorInterest-Only Loan Payment
Principal and APR—monthly interest-only payment (no amortization).
Use CalculatorOvertime 1.5× and 2× Pay
Regular, time-and-a-half, and double-time hours in one gross estimate.
Use CalculatorCombinations n choose r
Binomial coefficient C(n,r) with a stable multiplicative formula.
Use CalculatorGolden Ratio Layout
Given long or short side, find the other for φ ≈ 1.618 proportions.
Use CalculatorHalf-Life Remaining
Idealized (1/2)^(t / t½) fraction remaining for teaching sketches.
Use CalculatorBMR Calculator
Mifflin–St Jeor resting metabolic rate from weight, height, age, and sex.
Use CalculatorCorrected Calcium
Albumin-adjusted serum calcium (mg/dL or mmol/L)—multilingual medical-style tool.
Use CalculatorDreisatzrechner
Rule of three: direct, inverse, and percent proportions — multilingual (German default, English and more).
Use Calculator