Building Sigma: going public with the build

I am building Sigma, a notepad calculator for iPhone. Going for the App Store next week. First public update; I have been heads down a month.

The problem I kept hitting: I would tap out a stack of numbers on the iPhone calculator, get a result, screenshot it, and an hour later have no idea what 4218.50 was. Rent split? Trip total? Tax on something? The number is fine in the moment and useless ten minutes later because there is no context attached.

Sigma is a notepad where each line can be a calculation. You write words, you write math, the result shows up on the right. The words stay. Change an input, everything downstream updates.

Plain-English math: 20% tip on 84.50, rent + utilities, 120 EUR to USD. Variables that carry across lines, live currency rates, unit conversions, dates, percentages. Six themes, a built-in reference for everything the parser knows about, optional iCloud sync, export to PDF, Markdown, and plain text.

The pricing bet I am making:

Free tier is three saved sheets, full parser, no watermarks, no ads, no nag. Pro is $1.99/mo, $14.99/yr with a 7-day trial, or $29.99 lifetime. Auto-renews, cancel anytime in Settings.

Three sheets is the part I am most uncertain about. Generous enough that a non-paying user gets a real calculator, not a teaser. Tight enough that anyone using the app daily hits the limit. The analytics for "tried to create a fourth sheet" is the conversion proxy I will watch closest in the first two weeks. Could end up being too tight or way too loose; I will find out.

Next week: App Store listing, screenshots, submission. No public beta for 1.0; I am shipping straight to the store and leaning on crash reporting on the live build.

Waitlist: getsigma.app