Math for numbers you guess.

Every real decision runs on numbers nobody actually knows. What the renovation costs. How many hours the side project eats. Whether the raise covers the higher rent.

Most of us handle this two ways, and both are bad. Punch one made-up number into a calculator, get $47,382.19 back, and treat the false precision as an answer. Or build a spreadsheet with three tabs and a set of assumptions you will never open again.

Ballpark is the missing middle. Write what you actually believe — somewhere between 18 and 26 thousand — and it hands back a range, a middle, and a picture.

Download on the App Store

iPhone and iPad · iOS 18 or later

Ranges are as easy to type as numbers

Type quoted = $18k to $26k. The to key is the first thing on the keyboard. Names can contain spaces, so hours per week is just a variable, and every result updates as you type.

It never pretends to know more than you do

Answers are shown to the width of their own uncertainty. If the real answer is somewhere in the twenties of thousands, Ballpark says $18k to $26k — never a figure with four decimal places it hasn't earned.

It tells you what's worth finding out

This is the part that changes what you do next. Ballpark ranks every unknown in your model by how much of the uncertainty it is responsible for, and says so in a sentence: "Pinning down the contractor's rate would cut your uncertainty by more than half." That's your afternoon's research, decided.

Units catch your mistakes

Dollars per hour times hours gives you dollars. Dollars plus hours is an error, not a wrong number you find out about later.

Twelve worked examples to start from

Can I afford this house? What should I charge? Will the renovation blow up? How long will my savings last? Is the side project worth quitting for? Each one is written out with the reasoning, not just the arithmetic.

Your documents are just text files

Plain UTF-8, visible in the Files app. Open them anywhere, diff them, back them up, and keep them long after you've stopped using this app.

Ballpark works entirely on your device. No account, no network, nothing collected.