Six small tools that each answer one question. Pick the one you need, type your numbers and read the result on the page. Every one is free, needs no account and runs in your browser.
Last updated: November 8, 2026
Each calculator has its own page with an explanation, worked examples and answers to common questions.
Start from the question you have and open the calculator that fits it.
| Your question | Calculator | What you get |
|---|---|---|
| How old am I, exactly? | Age Calculator | Years, months and days, a live counter, a birthday countdown, milestone dates and your age on other planets. |
| What time should I go to bed or wake up? | Sleep Calculator | Times that line up with 90-minute sleep cycles, in wake-up or bedtime mode, plus a nap mode. |
| What is the time after, or between, two times? | Online Time Calculator | Add or subtract hours, minutes and seconds, find the clock time after a duration, or the time between two times, with an optional break. |
| Where does my money go each month? | Expense Calculator | Your total expenses, what is left over, your savings rate and a 50/30/20 check, from weekly, monthly or yearly amounts. |
| How many significant figures does this have? | Significant Figures Calculator | Count sig figs, add, subtract, multiply, divide and round with the right rule, with every step shown. |
| I need a strong password or PIN. | Random Password Generator | Pick a length and the characters you want, then copy a random password made with your browser secure random source. |
A few details from the individual calculators. If you work with words as well as numbers, the case converter and the online notepad run in your browser too.
The sleep calculator lines its results up with 90-minute sleep cycles. Treat the times as a planning guide, not a medical measurement.
It does not adjust for daylight saving time, so allow for a clock change yourself when you measure a long period.
It compares your spending with the 50/30/20 rule, which can look different in an expensive city or on a low income.
Each step is listed, so you can check the rule used and follow it in a lab report or homework answer.
The password generator uses your browser secure random source, and the strength shown is calculated, not guessed.
The values you enter are not uploaded, and the age calculator saves nothing when you close the page.
Working with words instead of numbers? These text tools work the same way: open, type, copy.
Short answers to what people ask most.
Yes. All six are free to use, with no sign-up and no account.
No. Each calculator runs in your browser, so values such as a date of birth, your expenses or the times you enter are not uploaded to a server. The password generator makes passwords in your browser and never sends or stores them.
Open the sleep calculator, enter when you must wake up or when you are going to bed, and it shows times that line up with 90-minute sleep cycles. There is a nap mode too.
It is a budgeting guideline that splits after-tax income into 50% for needs, 30% for wants and 20% for savings and debt repayment. The expense calculator shows how your own spending compares with it.
No. It uses plain clock time, so adjust by an hour yourself if a clock change falls inside the period you are measuring.