Best Free Reference & Conversion Tools Online (2025)
Quickly calculate tips, percentages, ages, BMI, and convert units, currencies, and timezones with free everyday reference tools.
Guide Overview
Not every calculation needs a specialized tool. Sometimes you just need to split a restaurant bill, convert miles to kilometers, or figure out the time in Tokyo. These everyday reference tools give you fast, accurate answers to the questions that come up in daily life, with no clutter or complexity.
Focus: everyday calculation utilities, quick reference tools
Tip and Bill Splitting Made Simple
The tip calculator handles the mental math that slows down every group dinner. Enter the bill total, choose a tip percentage, and specify the number of people to split it among. It shows the tip amount, total per person, and the grand total so there is no confusion when the check arrives. You can also use it to quickly calculate tips for service providers like hairdressers, valets, and delivery drivers where percentage norms differ.
Percentage and Unit Conversions You Use Every Day
What is 15 percent of 847? How many kilograms is 175 pounds? These are simple questions that are surprisingly annoying to compute in your head. The percentage calculator handles every variation including percentage of a number, percentage change between two numbers, and finding what percentage one number is of another. The unit converter covers length, weight, volume, temperature, and area with instant results as you type.
Currency and Timezone Tools for a Global World
Whether you are shopping from an international retailer, paying a foreign contractor, or scheduling a meeting across continents, currency and timezone conversions are daily necessities. The currency converter uses live exchange rates to give you accurate conversions between over 150 currencies. The timezone converter shows the current time in any city and helps you find overlapping working hours for international meetings without anyone joining a call at 3 AM.
Health and Age Calculators
The BMI calculator provides a quick health screening metric from your height and weight, showing where you fall on the underweight-to-obese scale. While BMI has limitations and does not account for muscle mass or body composition, it remains a useful starting point for health awareness. The age calculator computes your exact age in years, months, and days from your date of birth, which is handy for filling out forms, checking eligibility requirements, or just satisfying curiosity.
Inflation and Salary Conversion Tools
The inflation calculator shows how purchasing power changes over time, answering questions like how much would $50,000 in 2010 be worth in today's dollars. This is useful for salary negotiations, retirement planning, and understanding historical prices. The annual-to-monthly converter breaks down salary figures into monthly, weekly, daily, and hourly equivalents so you can compare compensation packages expressed in different time units.
Tools in This Guide
Use these tools in sequence based on your workflow needs.
Tip Calculator
Calculate tip amount and split the bill between friends. Supports custom tip percentages and per-person totals.
Use tool →Percentage Calculator
Calculate percentages, percentage change, and percentage of a number. Solve any percentage problem instantly.
Use tool →Age Calculator
Calculate your exact age in years, months, and days. Find the time between any two dates.
Use tool →BMI Calculator
Calculate your Body Mass Index (BMI) using height and weight. See your BMI category and healthy weight range.
Use tool →Unit Converter
Convert between units of length, weight, volume, temperature, speed, and more. Supports metric and imperial.
Use tool →Currency Converter
Convert between world currencies with approximate exchange rates. Supports USD, EUR, GBP, CAD, and 20+ currencies.
Use tool →Timezone Converter
Convert times across major global time zones and quickly schedule meetings across regions.
Use tool →Random Number Generator
Generate random numbers, random ranges, dice rolls, coin flips, and lottery numbers. Cryptographically secure.
Use tool →Inflation Calculator
Adjust historical prices for inflation and compare purchasing power across different years.
Use tool →Annual to Monthly/Weekly/Daily Converter
Convert annual income or costs into monthly, weekly, and daily figures for planning and budgeting.
Use tool →Frequently Asked Questions
How much should I tip at a restaurant?
Are the currency conversion rates accurate?
Is BMI an accurate measure of health?
How does the inflation calculator work?
Can I convert between any two units?
Last updated: June 1, 2025