Free online calculators & everyday tools
Aster Tools is a growing collection of fast, accurate online calculators. No sign-up, no installs — every calculation runs privately in your browser.
Popular tools
🎂Age CalculatorFree age calculator. Enter your date of birth to find your exact age in years, months, days, hours and your next birthday countdown.⚖️BMI CalculatorFree BMI calculator for adults. Enter height and weight in metric or imperial units to find your Body Mass Index and weight category.％Percentage CalculatorFree percentage calculator. Work out what percent of a number, percentage increase or decrease, and the percentage change between two values.🏦Loan CalculatorFree loan calculator. Estimate your monthly payment, total interest and payoff for personal, auto and student loans from the amount, rate and term.🏡Mortgage CalculatorFree mortgage calculator. Estimate your monthly home loan payment, total interest and payoff from the price, down payment, rate and term.📈Compound Interest CalculatorFree compound interest calculator. See how savings and investments grow over time with regular contributions and compounding.
Finance
View all →Loans, interest, tips and savings — money math made simple.
🏦Loan CalculatorFree loan calculator. Estimate your monthly payment, total interest and payoff for personal, auto and student loans from the amount, rate and term.🏡Mortgage CalculatorFree mortgage calculator. Estimate your monthly home loan payment, total interest and payoff from the price, down payment, rate and term.📈Compound Interest CalculatorFree compound interest calculator. See how savings and investments grow over time with regular contributions and compounding.🧾Tip CalculatorFree tip calculator. Work out the gratuity on any bill, split it between people, and see the total per person in seconds.🏷️Discount CalculatorFree discount calculator. Enter the original price and percent off to see the sale price and exactly how much you save.💹New NISA SimulatorFree New NISA (新NISA) simulator. Project your tax-free investment growth in Japan's NISA and see how much tax you save versus a taxable account.🎁Furusato Nozei CalculatorFree furusato nozei (ふるさと納税) calculator. Estimate your donation limit from salary and family — donate up to it for only ¥2,000 out of pocket.💴Japan Take-Home Pay CalculatorFree Japan take-home pay (手取り) calculator. Estimate your net salary after income tax, resident tax and social insurance, per year and per month.🏠Japan Mortgage + Property Tax CalculatorFree Japan home-ownership cost calculator. Estimate your monthly mortgage payment plus fixed-asset tax and city-planning tax (固定資産税・都市計画税) — the real monthly cost.🏛️Japan Inheritance & Gift Tax CalculatorFree Japan inheritance tax (相続税) and gift tax (贈与税) calculator. Estimate the total inheritance tax from the estate and heirs, or annual gift tax after the ¥1.1M exclusion.🔁Subscription Cost CalculatorFree subscription cost calculator. Add all your recurring subscriptions and see exactly how much they cost per month and per year. Spot what to cancel.📉Debt Payoff CalculatorFree debt payoff calculator. Add your debts, pick the snowball or avalanche method, and see how fast you'll be debt-free and how much interest you'll pay.📊Budget Calculator (50/30/20)Free 50/30/20 budget calculator. Enter your monthly take-home pay and see how much to put toward needs, wants and savings. Adjust the percentages to fit you.🎯Savings Goal CalculatorFree savings goal calculator. Enter your goal, what you've saved, and your monthly contribution to see how long it'll take — with optional interest growth.💳Credit Card Payoff CalculatorFree credit card payoff calculator. See how long it takes to clear your balance at a set payment, or the payment needed to be debt-free by a target date — plus total interest.🏡Mortgage Affordability CalculatorFree home affordability calculator. Enter your income, debts and down payment to estimate the home price and mortgage you can afford using the 28/36 rule.🧾Sales Tax CalculatorFree US sales tax calculator. Pick your state, add any local rate, and get the sales tax and total price — using 2024 state base rates.💷UK Take-Home Pay CalculatorFree UK salary calculator. Enter your gross salary to see your take-home pay after income tax and National Insurance, per year and per month (2024/25).💶German VAT Calculator (MwSt)Free German VAT calculator. Work out the Umsatzsteuer (19% or 7%) — net, tax and gross amounts, forwards or backwards.
Health
View all →Body, fitness and pregnancy calculators for everyday wellbeing.
⚖️BMI CalculatorFree BMI calculator for adults. Enter height and weight in metric or imperial units to find your Body Mass Index and weight category.🤰Pregnancy Due Date CalculatorFree pregnancy due date calculator. Estimate your baby's due date and current week from your last menstrual period (LMP).🍎Calorie CalculatorFree calorie calculator. Estimate your daily calorie needs (TDEE) and BMR to maintain, lose or gain weight using the Mifflin-St Jeor equation.
Date & Time
View all →Work out ages, durations and the time between two dates.
🎂Age CalculatorFree age calculator. Enter your date of birth to find your exact age in years, months, days, hours and your next birthday countdown.📆Date Difference CalculatorFree date difference calculator. Find the number of days, weeks, months and years between any two dates, with or without counting the end day.⏱️Hours CalculatorFree hours calculator. Work out the time between two times, subtract breaks, and optionally calculate pay — perfect for timesheets and work hours.
Math
View all →Percentages and quick everyday number crunching.
Converters
View all →Currency, units, temperature — convert anything in a tap.
💱Currency ConverterFree currency converter with daily exchange rates for USD, EUR, GBP, JPY and 25+ currencies. Convert any amount instantly in your browser.📐Unit ConverterFree unit converter for length, weight, volume, speed, area and data. Switch between metric and imperial units instantly.🌡️Temperature ConverterFree temperature converter. Convert between Celsius, Fahrenheit and Kelvin instantly — see all three at once.🌐Time Zone ConverterFree time zone converter. Convert any date and time between world time zones, see the difference, and plan calls and meetings across regions.🔳QR Code GeneratorFree QR code generator. Turn any text or URL into a QR code, customize the colors, and download a high-resolution PNG. No sign-up, all in your browser.
Text
View all →Word counts and everyday writing helpers.
Communication
View all →Practical helpers for clear, considerate messages.