It gets ridiculous how people do not understand that WITHHOLDING is not the same as TAXES due. If people WANT an employer to pull out a lot of money on interest-free loans to the government, that is their choice to be lazy about it.
Instead of hourly numbers, you can estimate your taxes by using last year's 1040EZ and any applicable state tax forms in about 10 minutes time. You need to have your gross year to date number and if bad about keeping track, that's your problem. You do not state your filing status of single or married, and dependent of someone or independent.
You only need a latest pay stub which should include year to date pay and withholding.
A W-4 form tells the employer what to take out, and you can put anything you want on the form as long as you don't owe taxes at the end of the year as more than 10% of total tax. A W-4 does not go to the government.
7.65% comes off the top for Social Security and Medicare for all W-2 employees.
The taxes will be whatever your annual income causes and if too much withheld, eventually you get the difference back.
At 19 years old, you are a young adult, and are supposed to understand basic arithmetic to estimate an annual earning number.
You will likely get a very large tax refund after filing taxes in February.
At $13 an hour, at a 2000 hour year, that's $26000 IF you actually earn that from January 1 2016 through Dec 31 2016, If you cannot be claimed as a dependent, $10,300 is not Federal income taxable.
$15,700 in taxable income, and will even add $100 in other interest and earnings for $15,800 taxable.
Your highest Federal tax is $1905 and highest state tax about $400 for maximum tax of $2305
8.87% is your highest possible effective tax rate plus 7.65% for 16.52% and net of 100-16.52%= 83.48%
assuming no medical insurance deduction you have not stated about either
At $13 per hour on 80 hours for $1040 gross pay, your net pay cannot be any less than $868. The rest should be returned when you file income taxes. And, that is the absolute worst case, where likely you get back a lot more. Despite any fake crying you hear from people, the bottom 40% of earners in the USA pay very little taxes and the bottom 20% end on average with a credit instead of paying taxes. The withholding issue you are doing yourself.
Your actual estimation can only be done with filing status, current gross YTD, expected income for the rest of the year, and taxes already withheld.
It is normal to have large amounts taken out when people decide not to do their own math. That is the vast majority of this country.