9 calculators
Everyday Calculators
Dates, trips and home projects, worked out in seconds
These everyday calculators settle the questions that come up at home: how many days are left, how many business days a deadline has, your exact age, the tip and who pays what, the gas for a road trip and the paint for a room.
See all 9 calculatorsThe key idea
Days left are not working days
Between November 1 and December 31, 2026 there are 60 days, but only 40 business days once weekends and the Veterans Day, Thanksgiving and Christmas holidays are taken out. Small calculations like this decide whether a plan fits.
What you can calculate
9 calculators, one for every question
Days Between Dates Calculator
Calendar days, weeks and business days between two dates.
Calculate 02Countdown Calculator: Days Until Christmas and More
Days, weeks and business days until a holiday or any date.
Calculate 03Age Calculator
Exact age in years, months and days, and the days to your next birthday.
Calculate 04Tip Calculator
Tip at any %, split per person and the % you tipped.
Calculate 05Gas Cost Calculator for a Road Trip
What a road trip costs in gas and what each person pays.
Calculate 06Paint Calculator for a Room
Wall square footage and gallons of paint for your room.
Calculate 07Electricity Cost Calculator
What each appliance adds to your electric bill.
Calculate 08Zodiac Sign Calculator
Your sign from your date of birth, plus your Chinese zodiac animal.
Calculate 09Random Number Generator
Random numbers or a drawing from a list of names.
CalculateHow we work
How we build calculators, in three principles
Diagnosis
Source first
Every formula comes from the law, the agency or the original study.
If a calculation depends on a rule (federal tax brackets, the Fair Labor Standards Act, Social Security), we start from the official text from the IRS, the Department of Labor or the SSA and link it on the page. If it depends on a study, we cite the study.
No figures copied from another calculator.
Method
Checked by hand
Every calculator is tested against cases worked out by hand.
The example on each page is one of those cases and matches the tool to the cent. We also test the edge cases: zeros, negatives, legal caps and odd dates.
When a rule changes, we review it and log the change on our corrections page.
Tool
Built to be understood
The result comes with the formula, the example and the common questions.
Everything runs in your browser, instantly and with no sign-up. You can share a calculation with a link, save it to your history or download it to Excel.
We do not store what you type.
Common questions
Frequently asked questions
How do I count business days between two dates?
Count Monday to Friday and take out holidays. The days between dates calculator does it with the 11 federal holidays on their observed dates.
How do I calculate a tip?
Multiply the bill by the tip percentage: 20% of $80 is $16. The tip calculator also splits the total between everyone at the table.
How much gas will my trip use?
Divide the miles by your car’s miles per gallon: 600 miles at 30 mpg is 20 gallons. Multiply by the price per gallon for the cost.
How much paint do I need?
Measure the wall area in square feet, take out doors and windows, multiply by the number of coats and divide by the coverage on the can.
Do the date calculators include holidays?
Yes, the federal holidays of 5 U.S.C. § 6103. State holidays and days your employer gives off are not included.
Is my data saved?
No. Everything runs in your browser and nothing you type is sent to a server.
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