Small math problems. Satisfying answers.
Sometimes you need to untangle a sale price. Sometimes you’re splitting a dinner check or wondering whether expensive shoes are actually worth it. These calculators give you the answer and explain the math, without making you feel like you’re back taking a test.
I build and improve them around the questions and decisions people run into in ordinary life. Grab whichever one helps today.
Stacked Discount & Checkout
Two coupons, sales tax and shipping. Find the actual total, then compare a simple alternative.
Tip & Split Bill
Tip before or after tax, account for an included service charge, and divide every last penny.
Percentage Calculator
Find a percent, percent change, a share, or reverse the math. The steps appear with the answer.
Cost Per Use / Wear
Compare two things by how much they cost each time you’ll actually use them.
Unit Price Comparison
Compare different package sizes and quantities without falling for a misleading bigger box.
Coffee Habit Cost
See where the daily coffee money goes, and what a less expensive alternative might save.
Trying to understand saving and compound interest?
Our new Compound Interest Calculator separates monthly deposits from projected growth and offers a printable two-year lesson. It is an educational scenario tool, not a financial-product pitch.
Checking a GPA or figuring out a final exam?
The new School & Grade Calculators collection includes a credit-weighted GPA calculator and a Final Grade calculator, both with a printable explanation of the math.
Measuring or building something?
Try the Home Project Calculators collection to work out concrete bags, square footage, mulch, paint, and flooring. Many include printable lessons that explain the math step by step.
Working on a room?
The Paint Gallons Calculator helps estimate walls, ceiling, coats, and a little waste before you buy paint. It also has an optional link to painting supplies.
Need to know how much flooring to buy?
Our new Flooring Boxes Calculator turns the sizes of up to three spaces into a count of whole boxes, with cuts and an optional repair spare included.
In the mood for something just for fun?
Try the new How Many Books Could You Read in a Year? calculator. See how fifteen or twenty reading minutes can turn into a surprisingly large shelf of books.
There are calculators for how old you’d be on another planet, how many seconds old you are, how many bananas tall you might be, and a few others that are just fun to try.
Shopping for something more complicated?
Our Shopping Tools collection helps compare vacuum types, dish racks, dehumidifiers, air purifiers, and repair-versus-replace decisions. Those include longer buying guides for anyone who wants to dig deeper.
Some shopping guides contain clearly disclosed affiliate links. The calculators here are free, and I don’t sell your input data.