Free Online Calculators
Fast, accurate calculators for every need. No signup required — just run the numbers.
⭐ Popular Calculators
🔄 Conversions
Acres to Hectares Converter
Convert acres to hectares for land surveys, farms, and real estate listings. Includes area …
Amps to Watts Converter
Convert amps to watts using voltage. Calculate power consumption from current and voltage for any …
Bar to PSI Converter
Convert bar to PSI and PSI to bar instantly. Essential for tire pressure, hydraulics, and gas …
Binary to Decimal Converter
Convert binary numbers to decimal and decimal to binary instantly. Supports up to 64-bit numbers. …
BTU to Watts Converter
Convert BTU/hr to watts and watts to BTU/hr. Used for air conditioning, heating, and appliance …
Celsius to Fahrenheit Converter
Convert Celsius to Fahrenheit, Kelvin, and Rankine in one step. Ideal for weather, science, and …
CM to Inches Converter
Convert centimeters to inches with decimal and fractional output. Essential for height, fabric, and …
Decimal to Fraction Converter
Convert any decimal number to a simplified fraction instantly. Shows step-by-step conversion using …
Dress Size Converter
Convert women's dress sizes between US, UK, EU, FR/ES, IT, and AU/NZ instantly. Try this free online …
Fahrenheit to Celsius Converter
Turn Fahrenheit readings into Celsius and Kelvin in seconds. Great for weather, cooking, and lab …
Feet to Meters Converter — Free ft to m Tool | RunCalc
Convert feet to meters instantly. Includes feet & inches to cm. Free, fast, no signup. Try it now!
Gallons to Liters Converter
Convert US gallons to liters and liters to gallons instantly. Accurate volume conversion with a …
40 Conversions calculators📅 Date & Time
Add Days to Date Calculator
Add or subtract any number of days to a date. Find the resulting date and day of the week instantly. …
Age Calculator
Calculate your exact age in years, months, days, hours, and minutes. Find out how many days you've …
Age Difference Calculator
Calculate the exact age difference between two people in years, months, and days. This free online …
Birthday Day Calculator
Find out what day of the week you were born on and what day your next birthday falls on. Use this …
Business Days Calculator
Count the number of business days (weekdays) between two dates, excluding weekends. Try this free …
Date Difference Calculator — Exact Days, Weeks & Months Between Dates
Calculate the exact number of days, weeks, months, and years between any two dates. Handles leap …
Days Between Dates Calculator
Calculate the exact number of days between two dates. Find business days, weekdays, weekends, and …
Days Until Calculator
Calculate how many days until a specific date. Countdown to birthdays, holidays, events, and …
Time Add Subtract Calculator
Add or subtract any combination of hours, minutes, and seconds from a start time. Perfect for …
Time Duration Calculator
Find the exact duration between two times in hours, minutes, and seconds. Great for work logs and …
Time Zone Converter
Convert time between time zones. See what time it is anywhere in the world right now. Try this free …
Weeks Calculator
Calculate the number of weeks between two dates or find a date a certain number of weeks from now. …
🏠 Everyday
Aspect Ratio Calculator
Calculate the aspect ratio of any width and height. Resize while maintaining proportions. Supports …
Bra Size Calculator
Find your correct bra size by entering your band and bust measurements. Get your size in US, UK, and …
Cat Age Calculator
Convert your cats age to human years. Cats age faster in their first two years. Use this free online …
Data Transfer Speed Calculator
Calculate how long it will take to transfer a file based on file size and network speed. Use this …
Dog Age Calculator
Convert your dogs age to human years using the latest scientific research. Try this free online tool …
Electricity Cost Calculator – How Much Does It Cost to Run an Appliance?
Calculate electricity cost for any appliance in seconds. Enter watts + hours used → get daily, …
Fuel Cost Calculator
Calculate trip fuel cost based on distance, fuel efficiency, and current gas price. Use this free …
Gas Mileage Calculator
Calculate your fuel efficiency in MPG or L/100km and estimate fuel costs. Try this free online tool …
Grade Calculator
Calculate your weighted average grade from multiple assignments and their weights. This free tool …
Hours Calculator
Calculate total hours worked between start and end times, with break deduction. Use this free online …
Love Calculator
Fun love compatibility calculator! Enter two names and see your love match percentage. Just for …
Moving Cost Calculator
Estimate your moving costs based on distance, home size, and number of movers needed. Use this free …
18 Everyday calculators💰 Finance
401k Calculator
Estimate your 401(k) retirement savings growth. See how contributions, employer match, and compound …
Amortization Calculator
Calculate your loan amortization schedule, monthly payment, total interest paid, and principal …
Auto Loan Calculator
Calculate monthly car payments, total interest, and total cost of an auto loan. Try this free online …
Bond Yield Calculator
Calculate bond yield to maturity (YTM), current yield, and annual interest income for any bond. This …
Break-Even Calculator
Calculate your break-even point in units and revenue. Find out how many units you need to sell to …
Budget Calculator
Calculate your monthly budget balance. Enter your income and total expenses to see your remaining …
Business Loan Calculator
Calculate monthly business loan payments, total interest, and cost of capital for any commercial …
CAGR Calculator
Calculate Compound Annual Growth Rate (CAGR) between any two values. Find the annualized return of …
Car Lease Calculator
Calculate your monthly car lease payment. Enter vehicle price, residual value, money factor, and …
CD Calculator (Certificate of Deposit)
Calculate the maturity value and interest earned on a Certificate of Deposit (CD). Supports simple …
Compound Interest Calculator
Free compound interest calculator using A = P(1+r/n)^(nt). Enter principal, annual rate, compounding …
Cost Per Unit Calculator
Calculate the cost per unit of any product or service. Compare prices to find the best value. This …
49 Finance calculators💪 Fitness & Health
Adjusted Body Weight Calculator
Calculate Adjusted Body Weight (AdjBW) for obese patients. Used in clinical settings for accurate …
Alcohol Unit Calculator
Calculate alcohol units in your drinks based on volume and ABV. Track weekly intake against health …
Baby Weight Percentile Calculator
Find your baby's weight percentile based on age and gender using WHO growth standards. Track healthy …
Blood Alcohol Calculator - Bac
Estimate Blood Alcohol Concentration (BAC) with the Widmark formula. See DUI legal limits by US …
Blood Alcohol Calculator - Blood Alcohol
Calculate your Blood Alcohol Content (BAC) based on drinks consumed, body weight, and time. Know …
Blood Pressure Calculator
Check your blood pressure reading and understand what your systolic and diastolic numbers mean. Find …
BMI Calculator
Free BMI calculator. Check if your weight is underweight, normal, overweight, or obese per WHO …
BMR Calculator
Free BMR calculator using Mifflin-St Jeor and Harris-Benedict equations. Find your Basal Metabolic …
Body Fat Percentage Calculator
Estimate your body fat percentage using the U.S. Navy method. Enter your measurements to get an …
Body Surface Area Calculator
Calculate your Body Surface Area (BSA) using the Mosteller, DuBois, or Haycock formula. Used for …
Calorie Deficit Calculator
Calculate the daily calorie deficit needed to reach your goal weight in your target timeframe. Based …
Child BMI Calculator – CDC Growth Chart Percentile
Calculate BMI for children and teens aged 2–19 with CDC growth chart percentile. Get age- and …
50 Fitness & Health calculators🔢 Math
Absolute Value Calculator
Calculate the absolute value of any number or expression. |x| returns the non-negative magnitude. …
Area Calculator
Calculate the area of common shapes: rectangle, circle, triangle, and trapezoid. This free online …
Average Calculator
Calculate the mean, median, mode, and range of any list of numbers instantly. Enter comma-separated …
Binary Calculator
Perform binary addition, subtraction, multiplication, and division. Convert between binary and …
Circle Calculator
Calculate the area, circumference, and diameter of a circle from the radius. Instant results with …
Cone Volume Calculator
Calculate a cone's volume, slant height, and surface area by entering radius and height. Instant …
Cross Product Calculator
Calculate the cross product of two 3D vectors with step-by-step solution. Use this free online math …
Cylinder Volume Calculator
Calculate the volume and surface area of a cylinder. Enter radius and height to get instant results. …
Distance Calculator
Find the straight-line distance between two points on a grid. Enter x and y coordinates for instant …
Distance Formula Calculator
Apply the distance formula √((x₂-x₁)²+(y₂-y₁)²) to find the length between any two points. …
Exponent Calculator
Calculate powers and exponents. Find the result of any base raised to any power. This free online …
Factorial Calculator
Calculate the factorial of any non-negative integer. n! = n × (n-1) × … × 2 × 1. This free online …
55 Math calculators🏃 Running
10K Training Pace Calculator
Calculate your ideal training paces for a 10K goal time. Get easy, tempo, interval, and long-run …
5K Training Pace Calculator
Get personalized training paces for your 5K goal time. Calculate easy, tempo, interval, and long-run …
Age Graded Running Calculator – WMA Age-Grading Performance Score
Calculate your age-graded running performance score. Compare your time to world-class athletes of …
Boston Marathon Qualifying Time Calculator – BQ Time by Age & Gender
Find your Boston Marathon qualifying time based on age and gender. See the official BAA qualifying …
Easy Run Pace Calculator
Calculate your recovery and easy run pace from a recent race result. Ensure you're training at the …
Elevation Gain Adjustment Calculator – Hill Running Pace Adjuster
Adjust your running pace for elevation gain and hills. Uses Minetti's energy cost equations to …
Half Marathon Pace Calculator – 13.1 Mile Split Planner
Plan your 13.1 mile race with a target finish time. Get per-mile and per-km paces plus every mile …
Heart Rate Drift Calculator
Estimate cardiac drift during long runs. Calculate how much your heart rate rises at the same pace …
Heat Running Pace Adjustment Calculator – Temperature & Humidity Effect
Adjust your expected running pace for heat and humidity. Calculate how much slower to run in hot …
Lactate Threshold Pace Calculator
Calculate your lactate threshold pace from recent race times. Find the exact pace for tempo runs to …
Marathon Pace Calculator – 26.2 Mile Split Planner
Set a 26.2 mile goal time and instantly see your required pace per mile and per km, with key …
Marathon Wall Calculator
Predict when you'll hit the wall in a marathon based on your glycogen stores, pace, and body weight. …
34 Running calculatorsFree Online Calculators for Every Need
Welcome to RunCalc — your go-to resource for free, accurate online calculators covering math, finance, health, fitness, running, and much more. No signup required. No ads cluttering your results. Just fast, reliable tools that work instantly in your browser.
What You’ll Find on RunCalc
RunCalc hosts 256+ calculators organized across dozens of categories, from everyday arithmetic to specialized financial planning tools. Whether you’re training for a marathon, budgeting your savings, or doing quick unit conversions, we have a calculator for that.
Top Categories:
- 🏃 Running & Fitness — Pace Calculator, VO2 Max Calculator, Calorie Calculator, Heart Rate Calculator
- 💰 Finance — Compound Interest Calculator, Loan Calculator, Emergency Fund Calculator, Debt Payoff Calculator
- 📐 Math — Percentage Calculator, Fraction Calculator, Square Root Calculator
- 🏥 Health — BMI Calculator, BMR Calculator, Ideal Weight Calculator
- 🔢 Unit Conversions — Miles to KM, KG to LBS, Celsius to Fahrenheit
Why Use RunCalc?
Free, always. Every calculator on this site is 100% free — no premium tiers, no paywalls, no account required. Just open the page and start calculating.
Fast and accurate. Our calculators run entirely in your browser. Results appear instantly as you type, with no server round-trips slowing you down. Formulas are verified against authoritative sources.
Available in 33 languages. RunCalc is fully localized for a global audience. Switch to your preferred language using the language selector at the top of any page.
Mobile-friendly. Every tool is designed to work beautifully on phones, tablets, and desktops alike.
Start Calculating
Browse by category, search for a specific calculator, or jump straight to one of our most popular tools above. If you can’t find what you’re looking for, check our full list of calculators — new tools are added regularly.