I have an app idea. Where do I start?

With a few written sentences about who it’s for and what they do with it.

• 01

  Write down who uses it and what each of them does, in order, in the words you’d use telling a friend.

• 02

  Get a rough number. The estimator on this site takes a paragraph and doesn’t charge for it.

• 03

  Decide whether to build it, buy something that already does most of it, or test the idea without building anything.

• 04

  Talk to people who build apps, with the description and the number in front of you.

Each step sets up the next. The number tells you whether buying is worth a look, and what you decide about buying changes what you say in the first conversation. Skip the first step and the other three are guesses.

Who uses it and what each of them does, in the order they do it. Features, screens and which phone can wait. Written that way, a one-line idea turns into a few plain sentences.

“An app for my cleaning customers”

Customers sign in on iPhone or Android, pick a time slot, pay by card and get a reminder the day before. Your staff see the day’s bookings on screens of their own in the same app. Two kinds of user, both phones.

“A swap app for our town”

People sign up, then post something they’re giving away, with a photo. Everyone else filters the list for what they want and claims it, and the person giving it away gets a notification. One kind of user, on both phones.

“Something so my team stops using paper”

Each person signs in on a web page, records a job and attaches its paperwork, and you get a report every Monday. One kind of user, in a browser.

The longer version is what gets priced. It’s also what anybody who builds apps will need from you, and you’re the only one who can write it. How to write an app brief covers everything a full description says. For a first number, a few sentences like these are enough.

For these three ideas as first versions, $25,000 to $42,000, depending on which one you have. Each is priced as if you have a logo and nothing else: no screens drawn, nothing built behind it, and a small number of people using it at first.

• 01

  The booking app: $30,000 – $42,000 over 13–19 weeks, one app that runs on iPhone and Android.

• 02

  The swap app: $25,000 – $36,000 over 12–17 weeks, on both phones.

• 03

  The team’s job tool: $25,000 – $35,000 over 12–17 weeks, in a browser.

None of the three gets smaller in the estimator. Its first-version option takes out whatever can wait until people are using the app, and on these three that saves too little for it to offer one. They’re first versions already.

The number covers the build. Keeping the app running after launch is a yearly cost of its own, and it starts once people are using it.

A different one for each idea. Sign-in stays in on the booking app and the team’s tool, because the staff screens and a record of who logged which job depend on it. Taken out one at a time:

The swap app: whether people need an account

$4,000. Without accounts, anyone can post and claim, and the app comes to $22,000 – $31,000. Accounts mean signing up, signing in, resetting a password, staying signed in and deleting the account, and each of those has screens and failures of its own. The photo is $2,500, the filter $2,500 and the notification $1,500.

The booking app: whether customers pay by card in the app

$6,000. Without it, customers book in the app and pay the way they do now, and it comes to $25,000 – $35,000. Refunds and declined cards are most of that, and what it costs to add payments covers the card company’s fee and why the app stores take nothing on a cleaning booking. The reminder is $2,000.

The team’s tool: whether the weekly report is in the first version

$4,500. Sign-in is worth the same $4,500, and it stays. Without the report, you read the week’s jobs off the list. A report looks like one screen, and underneath it’s a data job that has to stay quick as the records pile up. The attachments are $2,500.

Changing where it runs moved each of the three by $2,500 or less, whether that was one phone instead of two, a browser instead of phones, or phones instead of a browser. Web or phones goes through that choice.

One addition outweighs every decision above. A separate web page for you or your staff to run the app from adds $12,000 to $13,000 to the two phone apps, because it’s a second piece of software. Decide that one on purpose.

Test it first if you don’t know yet whether people want it. Buy if the app is for your own business and software you can subscribe to already does most of it. Build when neither is true and the number fits.

Testing doesn’t have to mean building. Even with its biggest decision taken out, none of the three comes in under $21,000, so if that’s more than you’d risk on a guess, run the idea by hand first.

• The cleaning company takes bookings by text for a month, sends the reminders itself, and asks customers whether they’d book on their phone if they could.
• The swap app starts as a group chat where people post photos, and you watch whether things get claimed.
• The team writes jobs into a shared form for a month, and you see whether anybody fills it in on a busy day.

If software you can subscribe to already does most of what you want, try it before you price a build. For a tool your own team uses, build or buy has the seat math.

Once it’s written down, you’ve seen a rough number and you know whether you’re building, and before you’ve spent anything on it. Both make the first conversation more useful, for you and for them.

You’ll be asked who uses it, what they do, what you already have, and whether it has to connect to anything else. The written version answers most of that before the call starts. What a studio needs to know to quote you has the answers that move a quote, with what each one is worth.

Bring the decision you’d make first, too. If you’d drop card payments to bring the booking app down, say so. That’s $6,000 on a $30,000 – $42,000 build, and nobody pricing it can know you’d trade it until you tell them.

Somebody who builds apps for a living can tell you on one call which parts of your idea are expensive and which aren’t. That’s worth having before anything gets drawn.