Category
Everyday
Practical calculators for daily life: percentages, tips, discounts, loan payments, BMI, fuel economy and unit prices at the supermarket. Each one shows how the answer is derived, so you can sanity-check the result instead of trusting a black box. Nothing to install, nothing to sign up for — open a page and get the number.
Percentage Calculator
Work out percentages, what-percent, and percent change in one place.
Everyday
Tip Calculator
Calculate the tip and split the total bill between people.
Everyday
BMI Calculator
Calculate Body Mass Index from height and weight, with a healthy range.
Everyday
Age Calculator
Calculate exact age in years, months, days — and find your next birthday.
Everyday
Compound Interest Calculator
Project how a starting balance grows with regular contributions, your interest rate, and your compounding frequency.
Everyday
Loan / Mortgage Calculator
Calculate the monthly payment, total interest, and full amortization schedule for any fixed-rate loan.
Everyday
Online Notepad
Distraction-free scratch pad that autosaves to your browser — no account, no upload, no ads.
Everyday
Tally Counter
A click counter that survives a refresh — multi-counter, custom step, goal alert, and keyboard shortcuts.
Everyday
Calorie / BMR / TDEE Calculator (Mifflin-St Jeor)
Estimate your basal metabolic rate, daily calorie needs, and cut/maintain/bulk targets — Mifflin-St Jeor formula.
Everyday
Sleep Cycle Calculator (90-min cycles)
Find the best bedtime or wake time aligned to 90-minute sleep cycles so you wake up between cycles, not mid-deep-sleep.
Everyday
Discount & Sale Price Calculator
Calculate the sale price after a percent or fixed discount — plus tax, savings, and effective discount rate.
Everyday
Pregnancy Due Date Calculator
Estimate your due date from LMP, conception date, or ultrasound — see current weeks and trimester.
Everyday
Body Fat % Calculator (US Navy Method)
Estimate body fat percentage from height, neck, waist (and hip for women) using the US Navy tape-measure formula.
Everyday
Macronutrient Calculator (Protein / Carbs / Fat)
Split your daily calories into grams of protein, carbs, and fat — IIFYM-style presets for balanced, low-carb, high-protein, or keto.
Everyday
GPA Calculator (4.0 / 4.3 / 4.5 scales)
Compute your weighted GPA across courses on US 4.0, US 4.3 (+ grades), or Korean 4.5 scales. Tracks total credits and quality points.
Everyday
Fuel Cost Calculator
Estimate the fuel cost of a trip from the distance, your vehicle's fuel economy and the fuel price — in L/100km or mpg, with optional round trip.
Everyday
Ideal Weight Calculator
Estimate ideal body weight from height and sex using the Devine, Robinson, Miller and Hamwi formulas — plus the healthy weight range for a normal BMI.
Everyday
Final Grade Calculator
Work out the score you need on your final exam to hit the course grade you want — plus your best and worst possible outcomes.
Everyday
Password Strength Checker
Estimate password strength via entropy and crack-time. Detects common passwords, sequences, and repeated characters. Nothing leaves your browser.
Everyday
Pace Calculator
Compute running pace, finish time, or distance from any two of them. Presets for 5K, 10K, half, and marathon.
Everyday
Time Card Calculator
Sum daily start/end times into a weekly total, subtract breaks, and split regular vs overtime. Optional hourly rate computes the paycheck.
Everyday
VAT / Sales Tax Calculator
Add tax to a net price or extract tax from a tax-inclusive price. Common VAT/GST/sales tax presets (5–25%).
Everyday
Salary Calculator
Convert between hourly, weekly, monthly, and yearly pay — with configurable work week and paid holidays.
Everyday
Cooking Conversions
Convert between cups, tablespoons, teaspoons, millilitres, and fluid ounces — and weigh common ingredients in grams or ounces.
Everyday
Pet Age in Human Years
Convert your dog or cat's age into the rough "human-year equivalent" — using vet-recommended scales, not the old multiply-by-seven myth.
Everyday
One Rep Max Calculator
Estimate your 1RM from a sub-maximal lift using six classic formulas (Epley, Brzycki, Lombardi, O'Conner, Wathan, Lander), with a percentage table.
Everyday
CAGR Calculator (Compound Annual Growth Rate)
Compute the compound annual growth rate linking a starting value to an ending value over N years, or solve for the end value or the time needed instead.
Everyday
Margin & Markup Calculator
Solve for selling price, profit margin, or maximum cost — and convert between margin %, markup %, and price multiplier instantly.
Everyday
Specialized tools32
Tools for narrower, more technical jobs: particular file formats, standards and professional fields. They work like every other tool here, entirely in your browser.
Korean Military Discharge Date Calculator
A Korean conscript's discharge date, days left, progress, halfway point and D-100 from the enlistment date: army 18, navy 20, air force 21 months.
Everyday
Tile Calculator
Work out how many floor or wall tiles you need for a room from its length, width and the tile size, with an adjustable waste allowance and boxes required.
Everyday
Stock Average Price Calculator (Averaging Down)
Find the average cost of shares bought at different prices and your gain or loss, and how many more to buy at today's price to reach a target average.
Everyday
Credit Card Instalment Fee Calculator (Korea)
Work out the fee and each payment for a Korean credit-card instalment plan from the amount, months, annual fee rate and any interest-free months.
Everyday
Dew Point & Humidity Calculator
Calculate the dew point and absolute humidity from temperature and relative humidity using the Magnus formula, with a comfort rating in °C or °F.
Everyday
Wind Chill Calculator (°C and °F)
Calculate the wind chill — how cold the air feels — from temperature and wind speed, in metric or imperial, in your browser.
Everyday
Heat Index & Humidex Calculator
How hot it feels: the NWS heat index, Canada's humidex and the Australian apparent temperature from air temperature, humidity and wind, with risk levels.
Everyday
Ovulation Calculator and Fertile Window
Estimate ovulation day, the fertile window and your next period from the first day of your last period and your cycle length, with the next six cycles.
Everyday
Heart Rate Zones Calculator
Compute your 5 training zones from age and resting HR — pick max-HR formula (Tanaka / Fox / Gulati) and method (%MHR or %HRR / Karvonen).
Everyday
IBAN Validator
Validate an International Bank Account Number — checks country code, length, and the mod-97 checksum. Supports 75+ countries.
Everyday
Coffee Brew Ratio Calculator
Pour-over, French press, AeroPress, espresso, cold brew — calculate coffee and water amounts from any ratio with method-specific defaults.
Everyday
Baker's Percentage Calculator
Scale bread recipes by baker's percentage — enter the flour weight and each ingredient as a percentage of flour to get exact grams and hydration.
Everyday
Water Intake Calculator
Estimate daily water needs from weight, activity, climate, and pregnancy/breastfeeding status — gives a target and a 4-block schedule.
Everyday
Electricity Cost Calculator
Estimate what any appliance costs to run — enter its wattage, hours per day and your rate per kWh to get daily, weekly, monthly and yearly energy and cost.
Everyday
Prorated Monthly Salary Calculator (Partial Month)
Prorate a monthly salary for a month you joined or left partway through: calendar-day, 30-day and working-day methods side by side.
Everyday
Keyboard Tester (Key Test and Rollover Check)
Press keys and watch them light up on an on-screen keyboard. Find dead keys, test ghosting and n-key rollover, and read key, code and keyCode values.
Everyday
CPS Test: Mouse Click Speed and Button Check
Measure clicks per second over 1, 5, 10, 30 or 60 seconds, and check every mouse button, the wheel and double-click faults.
Everyday
Dead Pixel Test for Monitors and Phones
Fill a monitor, laptop or phone screen with solid black, white, red, green and blue to find dead, hot and stuck pixels.
Everyday
What Is My Screen Resolution? (Hz and Scaling)
See your screen resolution, physical pixels, scaling (devicePixelRatio), browser window size, refresh rate, colour depth and HDR support at a glance.
Everyday
Online Metronome
Free online metronome: 20–300 BPM, 1 to 12 beats per bar, eighth, triplet and sixteenth subdivisions, accent and tap tempo, timed by the audio clock.
Everyday
Online Tone Generator (Frequency Generator)
Play a sine, square, sawtooth or triangle tone from 1 Hz to 22 kHz, on both or one channel, see the nearest note, and save it as a WAV file.
Everyday
White Noise Generator (Pink & Brown Noise)
Play white, pink or brown noise for sleep, focus or masking sounds, with a volume control, a sleep timer that fades out and WAV download.
Everyday
Speaker Test (Left/Right, Phase, Sweep)
Test speakers and headphones in the browser: left and right channels, phase (polarity) and a 20 Hz to 20 kHz sweep, with a level meter per channel.
Everyday
Gamepad Tester (Buttons and Stick Drift)
Test an Xbox, PlayStation, Switch Pro or other controller in the browser: every button, trigger pressure, stick position and drift, and vibration.
Everyday
Online Tuner (Guitar, Bass, Ukulele, Violin)
An online tuner that listens through your microphone and shows the note and how many cents off it is. Chromatic mode, standard tunings and an adjustable A4.
Everyday
Pyeong Calculator: Square Metres to Pyeong
Square metres to pyeong (the Korean area unit) and back, plus an apartment's exclusive and supply areas in pyeong. 1 pyeong = 400/121 m².
Everyday
Korean Savings & Deposit Interest Calculator
Interest on a Korean term deposit or monthly savings plan, simple or monthly compound, and what you keep after the 15.4% tax, 9.5% or none.
Everyday
Loan Prepayment Fee Calculator (Korea)
Work out the fee a Korean lender charges when you repay a loan early: amount × rate × remaining days ÷ fee period, free after 3 years.
Everyday
Body Surface Area Calculator
Compute Body Surface Area in m² using five published formulas — Mosteller, Du Bois, Haycock, Boyd, Gehan & George — side by side.
Everyday
Caffeine Half-Life Calculator
Pick a coffee, tea or cola dose and see how much caffeine is still in your system now, in an hour, in six, and when it drops below the sleep threshold.
Everyday
Unit Price Comparator
Compare grocery and shopping items by price-per-unit (price per gram, mL, or piece). Mass, volume, and count groups with imperial and metric units.
Everyday
NPV & IRR Calculator (with XIRR)
Net present value, every IRR, MIRR and payback for a list of cash flows — or XNPV and XIRR for dated ones — with the Excel NPV() trap shown.
Everyday