If you hated math, then calculators were your best friends. That hasn't changed for the adults in us. From the ancient abacus to the latest smartphone app, the humble calculator has helped you keep track of large numbers. But thanks to the web, a calculator isn't always about math or arithmetic.

Here are five useful but cool online calculators that can help you stay on top of your time, habits, sleep, and life itself.

Free Time Calculator: Visualize Your Free Time

Visualize Your Free Time

About 40% of our time is spent sleeping. That's a big but necessary chunk of your life. What about the rest? This free online calculator is a simple project by Erik Rood (who is a People Analyst at Google) that visualizes the total "free" time left in your life. The calculator is for everyone. It can be an early lesson on how to make all those free hours more meaningful.

Erik says,

This helps put into perspective sensitivity to things like working hours, commute, etc and how those factors stack up into a big time sink over long periods.

You can track your productivity with time management apps like RescueTime. But the Free Time Calculator gives you the big picture. Look at the graph and decide what you are going to do with the free time you have. Maybe, use it for personal growth and spend a little less time on social media.

Make Yourself Great Again: Take a Digital Look in the Mirror

Make Yourself Great Again

This free calculator takes the idea of the time and chops it into the details. It is designed to make you reflect on your lifestyle choices and the time you are spending on them. It is a personal calculator to help you find the average time you spend on distractions and opportunities.

Examples of the former include social media, commuting, TV etc. Opportunities include learning new skills, relationships, self-reflection etc. Each box also suggests approximate hours per week an average person spends on each activity. Track your time spent and use these as a rough benchmark for your own.

You can enter your own activities too. Enter the average time in each box and the calculator will spew out a balance sheet. You are good if good habits outweigh the bad. If not, then you have some tweaks to make.

Alternative: TV Alternatives from OmniCalculator

Life Expectancy Calculator: How Old You Will Live to Be?

Life Expectancy Calculator

It's wonderful to gaze into a crystal ball and figure out the future. We can only rely on a bit of science today, but not too accurately though. Life expectancy is the average number of years a person might live based on certain factors. A lot of actuarial science and studies like the Global Burden of Disease help to set the model.

They can help you with key life decisions---for instance, how much you should save for retirement, or how much time you have to accomplish your goals, and more.

Set a goal to begin with. Give the calculator data on your lifestyle choices and it will tell you the likelihood of your meeting your goals. The calculator considers the Canadian Physical Activity Guidelines that considers ethnicity. Find a similar calculator for your country and take it for a spin.

Alternative: Addiction calculator

Sleep Calculator: Go to Bed on Time

Sleep Calculator

Night owls know about the struggle to wake up early. The secret is in going to sleep at the right time and staying away from digital devices at bedtime. There are other secrets to sleep well and wake up rested, but let's focus on the right time to head to bed.

The simple Sleep Calculator works out the best time for you to rise or go to sleep. The calculator bases its calculations on our body's internal biological clock. Give it the time you need to wake up at or find out the time for your alarm if you feel sleepy now. Either way, there's a good chance you won't wake up on the wrong side of the bed.

Alternative: Slumber Bear [Broken URL Removed]

Junkies: Keep Binge Watching in Check

Calculate binge watching time

Junkies is a free and fun calculator that tells you the amount of time you "waste" on TV shows. Enter the name of the TV show, the season, and the episodes you watched to get the total hours spent on enjoying them. The readout can get embarrassing for binge watchers, so be careful whom you share the statistics with!

You can track your watched episodes and synchronize the data with your Google account. Of course, you can loop this back to the first and second calculators on our list and find out if screen time is getting out of hand.

Alternative: Tiii.me

Online Calculators Help Your Decisions

Online calculators work as decision-making shortcuts. Use the right calculator to put the vague into concrete figures and make the right change in your life. For instance, these calculators will tell you if you are saving enough for retirement. Take a look over the horizon and start working for it today.