Free Online Calculators: Dates, Percentages & Costs
Compare everyday quantities with explicit inputs. Work out percentages, date differences or the cost of recurring meetings, and change one input at a time to see how the result responds.
Recipe Scaler
Scale recipe ingredient quantities up or down for any number of servings instantly in your browser
Standard Deviation Calculator
Calculate standard deviation, variance, mean, median, mode, quartiles, and more — with step-by-step breakdown
Speed Distance Time Calculator
Calculate speed, distance, or time — enter any two values to solve for the third
Flooring Calculator
Calculate how much flooring you need for any room, including waste factor and cost estimate
Heat Index Calculator
Calculate the apparent "feels like" temperature from air temperature and relative humidity using the NWS Rothfusz equation. Shows heat danger levels.
Free Fall Calculator
Calculate free fall time, distance, and velocity for any planet gravity
APR to APY Calculator
Convert between Annual Percentage Rate and Annual Percentage Yield with compounding frequency support
NPV Calculator
Calculate net present value (NPV) and IRR from cash flows and a discount rate
Rule of 72 Calculator
Estimate how long it takes to double an investment using the Rule of 72
Frequency to Wavelength Calculator
Convert frequency to wavelength and back — supports Hz to THz and nm to km with EM spectrum region
Sunrise & Sunset Calculator
Calculate sunrise, sunset, golden hour, and twilight times for any location and date
Sales Tax Calculator
Calculate sales tax amount and total price — or remove tax from a total to find the pre-tax price. Includes common US state and international tax rate presets.
Slope Calculator
Calculate slope, distance, midpoint and line equation between two coordinate points
Tap Tempo BPM Calculator
Tap to find the BPM of any song or rhythm — see tempo name and note durations
Moon Phase Calculator
Calculate the moon phase for any date — see illumination %, lunar cycle progress, and upcoming new and full moon dates
Heart Rate Calculator
Calculate your maximum heart rate and 5 training zones by age — with Karvonen method support
Ohm's Law Calculator
Calculate voltage, current, resistance, and power using Ohm's Law. Enter any two values to solve the circuit.
Video Bitrate Calculator
Calculate the optimal video bitrate for streaming and encoding
Dew Point Calculator
Calculate dew point, heat index, and humidity comfort level from temperature and relative humidity. Instant, free, no signup.
Wind Chill Calculator
Calculate wind chill temperature and frostbite risk using the NOAA formula
Pixel Density Calculator (PPI)
Calculate pixels per inch (PPI) for any screen resolution and size
One Rep Max Calculator
Calculate your one rep max (1RM) using 5 proven formulas — then get a full training table with weights for every intensity level
Golden Ratio Calculator
Calculate golden ratio segments, golden rectangles, and check how close any two values are to phi (1.618).
Ohm's Law Calculator
Calculate voltage, current, resistance, and power using Ohm's Law. Instant V=IR solver for electronics and electrical engineering.
Resistor Color Code Calculator
Decode 4-band and 5-band resistor color codes to find resistance value and tolerance — free online tool
Prime Factorization Calculator
Find prime factors of any number. Shows prime factorization, exponential notation, and all divisors instantly.
BPM Calculator
Find the BPM of any song by tapping to the beat
Simple Interest Calculator
Calculate simple interest (I = P×r×t), total amount, and monthly schedule — free browser tool
FIRE Calculator
Calculate your Financial Independence Retire Early number and years to freedom
Triangle Calculator
Solve any triangle — enter any 3 known values to calculate all sides, angles, area, and properties
Net Worth Calculator
Calculate your net worth by adding up all assets and subtracting total liabilities
Combination & Permutation Calculator — nCr and nPr
Calculate combinations nCr and permutations nPr instantly with step-by-step factorial breakdown. Free online calculator.
Break-Even Calculator
Calculate break-even point in units and revenue for any business
Haversine Calculator
Calculate the great-circle distance between two latitude/longitude points. Instant results in km and miles with bearing and midpoint. No signup.
Percentage Calculator
Calculate percentages, percentage change, tips, and more
Age Calculator
Calculate your exact age in years, months, days, and more
BMI Calculator
Calculate your Body Mass Index and check your weight category
50/30/20 Budget Calculator
Calculate your budget using the 50/30/20 rule for financial planning
Tip Calculator
Calculate tips and split bills between friends
Pomodoro Timer
Stay focused with the Pomodoro technique timer
Aspect Ratio Calculator
Calculate and convert aspect ratios for images and video
Loan Calculator
Calculate monthly payments and total interest
Annuity Calculator
Calculate present value and future value of annuity payments with amortization schedule
Compound Interest Calculator
Calculate compound interest growth over time
CAGR Calculator
Calculate compound annual growth rate from start and end values
Profit Margin Calculator
Calculate profit and profit margin from cost and selling price.
ROI Calculator
Calculate return on investment
Debt-to-Income Ratio Calculator
Calculate your debt-to-income (DTI) ratio to see if you qualify for a mortgage or loan
Markup Calculator
Calculate markup on cost from cost and selling price.
Online Stopwatch
Simple stopwatch with lap times
Retirement Calculator
Calculate how much you need to retire and project your savings growth
Calorie Calculator
Calculate your daily calorie needs (BMR & TDEE) based on age, height, weight, and activity level.
Sleep Cycle Calculator
Calculate ideal bedtime and wake-up times based on 90-minute sleep cycles
Water Intake Calculator
Calculate how much water you should drink per day based on weight, activity level, climate, pregnancy, and breastfeeding
Brazil FGTS Calculator
FGTS deposits with TR + 3% a year, balance over time and the 40% fine
Brazil Net Salary Calculator 2026
Net CLT salary with 2026 INSS, income tax and the R$ 5,000 exemption
Brazil Termination Pay Calculator (Rescisão) 2026
CLT severance: notice, 13th, vacation, FGTS 40% fine and 2026 taxes
13th Salary Calculator (Brazil)
Brazilian 13th salary with both installments, INSS and income tax for 2026
Brazil Vacation Pay Calculator (Férias) 2026
CLT vacation pay with the 1/3 bonus, sold days, INSS and 2026 income tax
Brazil Overtime Calculator (Horas Extras)
CLT overtime at 50% and 100%, night premium with the short night hour, and DSR
Network Subnet Calculator
Network Subnet Calculator - Free online tool
Bandwidth Calculator
Bandwidth Calculator - Free online tool
Uptime Calculator
Calculate allowed downtime for any uptime SLA percentage — 99.9%, 99.99%, 99.999% and more
Split Bill Calculator
Split Bill Calculator - Free online tool
Grade Calculator
Grade Calculator - Free online tool
Scientific Calculator
Scientific Calculator - Free online tool
Statistics Calculator
Calculate mean, median, mode, standard deviation, and more
Probability Calculator
Calculate probability of events, compound probability, combinations, and permutations
Binary Calculator
Free binary calculator — add, subtract, multiply, divide and apply bitwise operations (AND, OR, XOR, NOT) on binary numbers. Results shown in binary, decimal, hex, and octal.
Hex Calculator
Hexadecimal arithmetic and bitwise operations with base conversion
Fraction Calculator
Fraction Calculator - Free online tool
Truth Table Generator
Truth Table Generator - Free online tool
Fibonacci Calculator
Fibonacci Calculator - Free online tool
Gcd Lcm Calculator
Gcd Lcm Calculator - Free online tool
Quadratic Formula Calculator
Solve quadratic equations ax²+bx+c=0 with step-by-step solution, discriminant, and roots
Area Calculator
Calculate the area of circles, rectangles, triangles, trapezoids, ellipses, and more
Body Fat Calculator
Calculate your body fat percentage using the US Navy method
Macro Calculator
Calculate your daily protein, fat, and carbohydrate targets in grams from any calorie goal
Ovulation Calculator
Find your ovulation day, fertile window and next period over three cycles
Due Date Calculator
Find your due date from your last period, conception or IVF transfer
Typing Speed Test
Test your typing speed and accuracy online for free
A/B Test Calculator
Calculate statistical significance for your A/B tests instantly
Days Until Calculator
Live countdown in days, hours and minutes to any date, with business days
Work Days Calculator
Work Days Calculator - Free online tool
Mortgage Amortization Calculator
Generate a complete mortgage amortization schedule with monthly and yearly payment breakdown
Spending Projection
Track your spending and income with a visual dashboard to project your financial future
Life in Weeks
See your whole life as a grid of weeks — one square per week, filled up to today
Meeting Cost Calculator
Price any meeting by the people in the room — per meeting, per year, and in hours burned
Caffeine Half-Life Calculator
Plot how much caffeine is still in your system at bedtime, drink by drink
CPS Test
Click speed test: how many clicks per second can you do in 1 to 60 seconds?
Hours Calculator
Add up work hours on a time card, with breaks, night shifts, overtime and pay
Reaction Time Test
Test your reflexes: click when the box changes colour, 5 tries, average in ms
Choose by the task you need to finish
- Use the meeting cost calculator to compare a one-off meeting with a weekly schedule.
- Choose a percentage or discount calculator to check a price change.
- Use date differences or a life-in-weeks calendar to explore time spans; review the assumptions shown by each calculator.