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Calc.

Free calculator widgets for your website

Any calculator on this site can run on your own page. Copy the embed code, paste it into your website, blog or course page, and your readers get the full calculator without leaving your site.

  • Free, with no sign-up and no ads inside the widget.
  • Works on phones and desktops; the widget fills the width of your column.
  • The numbers your readers enter stay in their browser and are not sent to us.
  • Each calculator is reviewed against published sources (see how we check our calculators).

The code is an <iframe> plus a short credit link under it. Please keep the link so your readers can find the full version with the formula, worked examples and sources.

Our most-used calculators

Every other calculator has the same “Embed this calculator” button under its result. Browse all calculators to find one for your topic.

  • Historical Travel Time Calculator

    Estimate how long a journey took in a historical era by selecting the transportation method (on foot, horseback, wagon, canal boat, stagecoach, Pony Express relay, river steamboat, early automobile or railroad), the terrain, the weather and the hours travelled each day. Useful for historians, writers, genealogists and game designers recreating pre-modern travel.

  • Historical Currency Value Calculator

    Convert a historical sum of money into its modern U.S. dollar equivalent using the official Consumer Price Index, with pounds and gold converted at their fixed historical dollar rates. Useful for researchers, writers and anyone comparing old prices with today's.

  • Rainfall Intensity Calculator

    Compute rainfall intensity by dividing total rainfall by the duration in hours. Returns inches per hour, a standard metric for designing drainage and assessing flood risk.

  • Vehicle Wear & Tear Calculator

    Estimates the wear-and-tear cost your vehicle incurs on a road trip, factoring in mileage, vehicle age, type, and road conditions. Ideal for budgeting trips or comparing route costs before you leave.

  • mg to mL Calculator (with Concentration)

    Convert a mg dose to mL (or mL back to mg) using a solution concentration. Preset picks for common pediatric and adult liquid medication concentrations.

  • A1C Calculator

    Convert HbA1c to estimated average blood glucose (eAG) or the other way, using the ADAG standard formula. Interpretation bands cover normal, prediabetes, and diabetes thresholds.

  • Wavelength to Frequency Calculator

    Convert the wavelength of light or radio waves to frequency with f = c ÷ λ. Enter the wavelength in m, cm, mm, µm or nm and read the frequency in Hz, kHz, MHz, GHz or THz.

  • Culvert Sizing Calculator

    Calculate the required culvert diameter to safely pass design stormwater flows under roads, driveways, or embankments. Helps engineers and contractors avoid undersized culverts that cause flooding or washouts.

  • Daily Fluid Requirements Calculator

    Estimates a patient's daily fluid needs using the Holliday-Segar method, a tiered weight-based formula. Used by clinicians and nurses to calculate maintenance IV fluids or oral fluid targets for pediatric and adult patients.

  • Fantasy Waiver Priority Calculator

    Estimate the ideal FAAB bid for a waiver wire pickup based on your remaining budget, the player's value tier, weeks left, and how badly you need the position. Best used each waiver period to avoid overbidding or underbidding.

  • Fabric Gathering Ratio Calculator

    Calculate the pre-gathered fabric length needed to achieve the right fullness for ruffles, skirt hems, and sleeves. Accounts for gathering ratio, fabric drape, and hem allowances.

  • Fantasy Waiver Wire Priority Calculator

    Determine the right amount of FAAB budget or waiver priority to spend on a free-agent pickup by comparing projected versus current player points, remaining weeks, and positional need. Use it every waiver period to avoid overpaying or underspending on critical roster upgrades.

  • Solar Time vs Clock Time Calculator

    Convert standard clock time to true solar time for any location and date. Useful for astronomers, sundial builders, and anyone tracking solar noon or sunrise/sunset times precisely.

  • Solar Radiation Calculator

    Estimate top-of-atmosphere solar irradiance at solar noon for a given latitude, day of year, and solar declination. Returns watts per square metre on a horizontal surface, before atmospheric attenuation.

  • Flight Fuel Cost Calculator by Aircraft Class or Burn Rate

    Estimate a trip's fuel cost from distance in nautical miles, the aircraft class (or your own fuel burn in gal/hr and airspeed), headwind and fuel price, with an altitude adjustment and an optional percentage fuel reserve. Useful for pilots and charter operators planning trip budgets and comparing route economics.

  • Elastic Length Calculator

    Compute the cut length of elastic for a waistband, cuff, or casing so it grips comfortably without cutting in or sliding. Useful for any garment with an elastic-pull-on closure: PJ pants, leggings, gathered skirts, sleeve cuffs.

  • Historical Wage Comparison Calculator

    See what a historical salary would be worth in today's terms by adjusting for wage growth and cost-of-living changes. Useful for comparing pay across generations or evaluating historical living standards.

  • Chess Rating Progress Tracker

    Estimate how many months it will take to reach your target chess rating given your recent progress, study hours, and weekly game volume. Perfect for setting realistic improvement milestones.

  • Historical Era Converter

    Convert any CE/AD year into the Islamic (AH), Hebrew, Buddhist, or Chinese calendar equivalent in seconds. Ideal for historians, students, and researchers working with multi-cultural chronologies.

  • Historical Salary Equivalent Calculator

    Convert a historical salary into its modern equivalent by applying an inflation multiplier, with an optional flat allowance for a costlier location. Great for comparing wages across eras.

  • Military Time Converter

    Convert between 12-hour AM/PM civilian time and 24-hour military time. Returns the time in the opposite format.

  • Pediatric Fluid Requirements Calculator

    Calculates a child's daily fluid requirement in milliliters using the Holliday-Segar method, adjusted for activity level and clinical conditions like fever or dehydration. Ideal for parents, nurses, and pediatric caregivers.

  • Sun Angle Calculator

    Estimate the sun's maximum elevation angle above the horizon for a given latitude and day of year. Useful for solar panel placement, shading analysis, and understanding seasonal daylight variation.

  • Historical Inflation Calculator

    Find out what a past dollar amount is worth today — or what today's money was worth decades ago. Compare prices, wages or savings across any two years using an average annual inflation rate, with a CPI table for U.S. dollars since 1913.

  • Dynasty Duration Calculator

    Calculate how many years a dynasty, reign, or ruling period lasted. Enter start and end years to instantly find the duration — useful for history students and researchers.

  • Yoga Studio Space Calculator

    Calculate how many yoga mats fit safely in a studio room given mat dimensions and required clearance between practitioners. Essential for studio owners planning class sizes.

  • Fabric Gathering Calculator

    Compute the flat cut length of fabric needed to gather down to a target finished length, using a chosen gather ratio. Useful for ruffles, gathered skirts, curtain headers, and shirring projects.

  • XP Per Hour Calculator

    Calculate experience points (XP) gained per hour by dividing the XP change over a measured time interval by the elapsed hours. Use it to optimize grinding routes, compare farm spots, or estimate time-to-next-level when planning long progression sessions.

  • Swimming Time Conversion Calculator

    Convert a swimmer's time between short course yards (SCY), short course meters (SCM), and long course meters (LCM). Essential for comparing times across different pool formats or predicting performance at a new meet.

  • Toilet Flush Volume Calculator

    Computes the volume of water used per flush by measuring the internal dimensions of the toilet tank. Ideal for identifying water-wasting fixtures, calculating household water consumption, or qualifying for rebate programs.