Free online tools that work while you sleep
20 fast, private calculators, converters and generators. No signup, no uploads — every tool runs entirely in your browser.
Age Calculator
Your exact age in years, months and days — plus a countdown to your next birthday.
💯Percentage Calculator
Percent of a number, what percent X is of Y, and percentage increase or decrease.
📈Compound Interest Calculator
See how savings grow with compound interest and monthly deposits — with a year-by-year table.
😴Sleep Cycle Calculator
Best bedtimes to wake up refreshed, based on 90-minute sleep cycles.
📅Date Calculator
Days between two dates (with business days), or add / subtract days, weeks, months and years.
⚖️BMI Calculator
Body Mass Index in metric or imperial units, with your healthy weight range.
✍️Word Counter
Live word, character, sentence and paragraph counts with reading time.
🔐Password Generator
Strong random passwords generated locally with crypto-grade randomness.
💵Tip Calculator
Tip amount, total and per-person split in one tap.
🔄Unit Converter
Length, weight, volume, area, speed, data and temperature conversions.
🏦Loan Calculator
Monthly payment and total interest for any loan — plus extra-payment savings.
💧Water Intake Calculator
Personalized daily water goal based on weight, activity and climate.
🧾Invoice Generator
Create a clean, professional invoice and save it as PDF — free, no signup.
🔤Case Converter
UPPERCASE, lowercase, Title, Sentence, camelCase, snake_case and more.
⏱️Hours Calculator
Hours between two times, plus a weekly time-card total in decimal hours for payroll.
🏷️Discount Calculator
Percent off, the price you pay and what you saved — plus two reverse modes.
🧮Sales Tax Calculator
Add sales tax, VAT or GST to a price — or strip it back out of a tax-inclusive total.
🎓GPA Calculator
Credit-weighted GPA from your course grades and credit hours, on the 4.0 scale.
🔥Calorie Calculator
Your BMR and daily calorie needs (TDEE), plus targets for losing or gaining weight.
🌍Time Zone Converter
Convert a date and time between any two time zones, with daylight saving handled.
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Why LazyTools?
Every calculation happens on your device. Your numbers, dates and text are never uploaded, logged or sold.
No accounts, no paywalls, no “upgrade to see results”. Open a tool, use it, done.
Tools don't sleep — 3 a.m. invoicing or exam-morning age checks are equally welcome.
Loads fast on any phone or computer, even on slow connections, in dark or light mode.
How LazyTools keeps the lights on
The tools are free because the site shows unobtrusive ads and occasional affiliate links. That's the whole business model — no data selling, no subscriptions. If a tool saved you time, sharing it with a friend is the best thank-you.