Free online calculators

Estimate the gas cost of any trip from distance, fuel economy, and the price per gallon.

Figure out what it costs to top off your tank from its current level.

Compute real miles per gallon from your odometer and gallons pumped.

Calculate average speed from distance and time — supports hours and minutes.

Estimate driving time including planned rest stops.

Add up gas, insurance, and parking for the full year of commuting.

Total a road trip budget: gas, hotels, and food, in one shot.

See what charging your electric vehicle actually costs per month at home rates.

Estimate weekly and yearly home charging cost for your Tesla model.

Estimate your car's current value after years and mileage.

See how much carpooling cuts your annual commute cost.

Calculate your bra size from band and bust measurements.

Find your ideal weighted blanket weight using the 10% rule.

Find the right tablecloth size for any table and desired drop length.

Compute fabric size and waist radius for a full circle skirt.

Compute the monthly cost of running any appliance from wattage and use.

Estimate how many gallons of paint your room needs.

Compute square footage and material needed including waste factor.

Count tiles needed for any room with waste built in.

Estimate monthly payments including principal, interest, taxes, and insurance.

Estimate annual savings and payback period for a residential solar install.

Find the BTU rating you need to properly cool a room.

Compute the tip and per-person split for any bill.

Find the sale price and savings for any percent off.

Convert an annual salary into an hourly rate.

Convert an hourly wage to monthly and annual income.

Compute return on investment and annualized return.

Compute gross profit and margin from revenue and cost.

Work out the hourly rate you need to charge to hit your income goal.

Plan focus blocks and breaks using the 25/5 pomodoro technique.

Compute weekly pay with overtime at 1.5x past 40 hours.

Calculate what a meeting truly costs in payroll dollars.

Calculate exact age in years, months, and days from any date of birth.

How many days, hours, and minutes are left until Christmas Day?

Find optimal wake-up or bedtime based on 90-minute sleep cycles.

Estimate your due date and current pregnancy week from your last period.

Count working days (Mon–Fri) between any two dates.

Flip a virtual coin — heads or tails, fair random.

Roll any combination of D4, D6, D8, D10, D12, D20, or D100.

Generate random numbers in any range, with or without duplicates.

Let randomness decide. A fair coin flip with words.

Look up your Western astrological sign from your date of birth.

Just-for-fun compatibility score from two names.

Compute the yearly cost of your showers in water and energy.

How much sunscreen you actually need per day at the beach.

Estimate how long a book or article will take to read.

See how much time you save listening at higher playback speeds.

Body Mass Index from height and weight, with the standard category breakdown.

Estimate daily calorie needs via Mifflin-St Jeor BMR and activity multiplier.

Estimate your daily water target adjusted for activity and climate.

Convert step counts to miles using your stride length or height estimate.

Solve any percentage question: X% of Y, X is what % of Y, percent change.

Compute area for rectangles, circles, and triangles in square feet.

Convert any number 1–3999 to a Roman numeral and back.

Convert between binary and decimal in either direction.

Add, subtract, multiply, or divide two fractions with auto-simplification.

Quick approximate currency conversion using static reference rates.

Translate any text into Pig Latin instantly.

Flip your text upside down with Unicode tricks.

Count words, characters, and reading time for any text.

Compute horsepower from engine torque and RPM using the standard SAE formula.

Decode a tire size into overall diameter, sidewall height, and circumference.

Engine static compression ratio from bore, stroke, deck, gasket, and chamber volumes.

Compute engine RPM at a given speed from tire size, gear, and final drive.

Estimate 0-60 mph time from horsepower, weight, and drivetrain.

Estimate WHP at the wheels after drivetrain losses.

Estimate compressor airflow target for a turbo build.

Estimate boosted HP from a naturally-aspirated baseline and boost pressure.

Compute brake-specific fuel consumption from fuel flow and brake horsepower.

Compute wheel offset in mm from width and backspacing.

Estimate the right driven-gear tooth count for accurate speedometer reading.

Estimate top boat speed from HP and weight using Crouch's planing formula.

Convert between nautical miles, statute miles, and kilometers.

Resolve runway wind into headwind and crosswind components.

Estimate cosmic-ray radiation dose for a flight.

Total your truck's loaded weight and see which GVWR class it falls into.

Estimate fuel flow demand and per-injector load for a given HP target.

Compute traffic density (vehicles per mile) from flow rate and speed.

Find the minimum winch capacity for your vehicle and terrain.

Compare pay-as-you-go parking against a monthly pass.

Compare DIY vs shop oil changes over a year of driving.

Rough estimate of annual auto insurance premiums by age, vehicle, and coverage.

Compute road-bike speed from cadence, gearing, and wheel size.

Compare driving cost against a train ticket, including the value of your time.

Estimate CO₂ emissions for any trip by mode and distance.

Compare monthly rideshare spend against the full cost of car ownership.

Estimate the cash value of your airline miles by program and redemption.

Total annual driving miles from commuting, leisure, and road trips.

Convert engine hours (on a marine or industrial engine) to equivalent automotive miles.

Solve any of distance, speed, or time given the other two.

Add up weekly, monthly, and annual toll spend — and the E-ZPass discount.

Estimate flight time from distance, cruise speed, and layover length.

Should you buy event tickets now or wait? A simple heuristic by time-to-event and category.

Convert between US Men, US Women, UK, EU, and CM shoe sizes.

Convert between US, UK, EU, and inner diameter / circumference ring sizes.

Find your US, UK, and EU dress size from bust, waist, and hip measurements.

Get your W × L jeans size from waist and inseam measurements.

Find your hat size in numeric, fitted, and S/M/L formats from head circumference.

Find the belt size to order from your pants waist or measured waist.

Find your jacket size and length from chest, height, and weight.

Find your glove size from hand circumference at the knuckles.

Convert shoe size to sock size (S/M/L/XL).

Get your t-shirt size from chest and waist measurements.

Get your W × L pants size and a hip-to-waist ratio flag.

Convert women's top sizes across US, UK, EU, AU, IT, FR, and JP.

Convert US shoe sizes to UK in either men's or women's sizing.

Convert UK shoe sizes to US in either men's or women's sizing.

Convert between men's and women's US shoe sizes (1.5-size offset).

Convert measured foot length to US toddler/youth shoe size.

How many skeins you need for a project, with a 10% safety buffer.

Convert knitting needle sizes between US, metric (mm), and old UK numbering.

Compute strips and yardage for quilt binding.

Cut size and square count for half-square triangles.

Compute panel width and required fabric for window curtains.

Find elastic length for waistbands, cuffs, and necklines.

Estimate thread consumed by a seam from length and stitch type.

Find the right shoelace length for your shoe and lacing style.

Estimate how many socks you've lost to the laundry over the years.

Get top and bottom bikini sizes from bra size and hip measurement.

Calculate rolls of wallpaper needed for a room, with waste and pattern repeat.

Check if your target rent fits the 30% rule and standard DTI limits.

Get a price range for kitchen, bath, basement, and other renovations.

Estimate the cost of a local, long-distance, or interstate move.

Compute lawn area in square feet and acres, plus seed and mowing estimates.

Estimate fence cost by perimeter, material, height, and gate count.

Pick the right storage unit size for your home and items.

Find the right tree height and width for your room.

Estimate how many hours a candle will burn from size, wick count, and wax type.

Find recommended R-value and additional insulation needed by climate zone.

Find the right roll-off dumpster size for your project.

See $-per-Mbps and whether your plan suits your usage.

Estimate monthly water usage and cost from household activity.

Calculate your weighted GPA across up to 6 courses, with letter grades and credit hours.

Compute your weighted course grade across up to 5 assignments.

Compute percentage and letter grade from correct answers.

Daily, weekly, and monthly hours from start time, end time, and breaks.

Subtotal, discount, tax, and total for up to 5 line items.

Units and revenue needed to cover fixed and variable costs.

Characters, words, Twitter remaining, and SMS segments for any text.

Score a password's strength locally based on length, variety, and patterns.

Convert between px, pt, em, rem, vw, and percent at a chosen base.

Approximate scaled SAT scores from raw section scores.

Spell out any number up to a trillion in English.

Reverse a string character-by-character or word order.

Spell any word using the NATO phonetic alphabet.

Plan study hours per subject given an exam date and difficulty.

Convert a time between major world time zones.

Find your retirement date and time remaining based on age and country.

Count down to your next birthday from today's date.

Count working days between two dates, excluding US federal holidays.

Find the best bedtimes to wake refreshed at a target time.

Find the best wake times after a chosen bedtime.

Count down the days, hours, and minutes to any future date.

Count years, months, days, weeks, and hours since a past date.

Convert international age to traditional Korean age.

Find the moon phase, illumination, and next full moon for any date.

Find all palindrome dates in a given year.

Check whether a year is a leap year, plus the next and last leap year.

Difference between two times in hours, minutes, and seconds.

Convert HH:MM to a decimal hour value and back.

Plan your audiobook reading pace and yearly book goals.

Total runtime of a series across seasons, episodes, and lengths.

Find your binge finish date based on daily watch time.

Hang point height, tree spacing, and strap length for a comfy hammock.

How many balloons does it take to lift a given weight?

Find the right tent capacity for your campers, gear, and style.

Compute Life Path and Name numbers from your DOB and full name.

Generate lottery-style numbers seeded by your name and today's date.

Convert between real minutes and Minecraft in-game days.

Convert Robux to dollars (and back) at both direct buy and DevEx rates.

Rough heads-up and multi-way win probability by hole-card category.

Compute your new Elo after a single game vs an opponent.

Daily protein target by body weight, activity level, and goal.

Daily calories, protein, fat, and carb targets from your body and goal.

Estimate body fat percentage with the US Navy method.

Compare your weight to Devine, Robinson, Miller, Hamwi, and healthy-BMI ranges.

Find pace, time, or distance from any two of the three.

Calories burned for any activity using MET values.

Estimate diapers needed and cost by baby's age and brand.

Total estimated cost of delivery plus the first five years.

Estimate expected expiration date by item type.

Estimate hours to charge a battery from current to target level.

Total linear inches and airline carry-on / checked classification.

How much amp power your headphones need to hit a target SPL.

Compute gallons of water in a well from diameter and depth.

Find the right gallon-rated bag size for your trash can.

Compute mat, frame, and overall sizes for any artwork.

Compute volume in cubic feet, yards, meters, and liters.

Convert between hexadecimal and decimal, with binary preview.

Evaluate math expressions with sin/cos/tan, log, sqrt, pi, e, and more.

Convert a letter grade or percentage into GPA points.

Track progress on a yearly reading goal and project your finish date.

Estimate hours to read a book at your pace.

Measure your actual reading speed in pages per hour and words per minute.

Typical word counts and page estimates by genre.

Are you on pace for your Goodreads reading challenge?

Convert KOLL Kindle pages to print pages and words.

Find out whether baths or showers are cheaper for you over a year.

Months to grow your hair to a target length.

Annual cost of your beauty routine.

Tubes per year and annual toothpaste cost.

WHO-recommended hand-washing time and song references.

Roll up the per-day and per-year cost of your skincare routine.

How many weeks a perfume bottle will last at your usage.

Annual hair color cost by method and frequency.

Annual cost of your makeup kit.

How long a bar of soap lasts and the monthly cost.

Masks needed per month and annual cost by type.

Where your income ranks against US (and rough global) distributions.

Compute net worth from assets minus liabilities; compare to age peers.

Rough IQ estimate from a raw test score — strictly informal.

Score a player line in standard, PPR, or half-PPR scoring.

Estimate reach and revenue lost if your account is banned.

What you could do instead of scrolling TikTok for X minutes a day.

Yearly hours sunk into social media — and what they could become.

Convert between pixels and physical inches at any PPI.

Combine pounds and ounces into total weight in oz, grams, kg, and decimal lbs.

Convert, add, or subtract feet-and-inches values.

Convert feet+inches height to inches, cm, and meters with a percentile note.

Compute area in acres from any shape's dimensions.

Land area in acres, hectares, bigha, katha, gaj, cent, and marla.

Convert lot size in square feet (or L×W) to acres and other units.

Convert acres or other area units to square feet and find the side of a square lot.

Solve scaled, real, or ratio given the other two.

How long a file will take to download at a given connection speed.

Compute horsepower from torque and RPM (or torque from HP and RPM).

Compute amperage from wattage at a chosen voltage.

Compute wattage from amperage at a chosen voltage.

Convert between energy (kWh) and average power (kW) over a time period.

Logarithmic conversion between dBm and watts.

Compute RMS and peak power from RMS voltage and impedance.

Convert energy and charge (or capacitance) into voltage.

Pressure converted across all weather units with a forecast hint.

Parts-per-million across PPM, PPB, ppt, percent, and mg/L.

Convert between Rockwell C, Rockwell B, Brinell, Vickers, and Shore D.

Simplify, scale, percentage-ize, or split a ratio.

One-stop imperial→metric conversion across length, weight, volume, temperature, speed.

Convert metric to imperial across length, weight, volume, temperature, and speed.

Educational unit-conversion chain across length, weight, volume, speed, temperature.