Most phone-reduction tools let you pick your own number. We don't. The number IS the product, and picking it wrong defeats the whole thing.
The first time someone tries Thirty, the question is always the same: "Can I set it to an hour? Maybe two? Just to start?"
The answer is no. There is exactly one number and it's 30. That's the design. Here's why.
The research on phone use and cognitive cost converges on a soft threshold somewhere between 30 and 90 minutes a day. Below that, no measurable harm to attention, sleep, or mood baseline. Between 90 and 180, mild cost. Above 180 (3 hours), the cost climbs sharply — and after about 4 hours a day, you start losing chunks of focused attention you don't get back without months of recovery.
The honest version: 30 minutes is conservative. Most people would be fine at 60. But "fine" isn't the goal. The goal is to push you toward the low end of the safe range, where the upside is biggest and the downside is zero.
60 minutes a day sounds reasonable. It's the number people pick for themselves when they're setting a budget. It also doesn't work.
Here's why. At 60 minutes, the cap is loose enough that you can have a "normal phone day" — half an hour of Instagram in the morning, half an hour of YouTube at night — and the cap is the only friction you experience. You don't actually change your behavior; you just feel slightly constrained.
At 30 minutes, the cap forces a real decision every time you reach for the phone. Is this worth 5% of my daily budget? Usually the answer is no. The cap stops being a budget and becomes a forcing function.
People who try Thirty at 30 minutes report behavior change in week 1. People who would try it at 60 minutes (we know because they ask) would report a mild annoyance and unchanged habits.
The opposite mistake. At 20 minutes a day, the cap is so tight that any single legitimate use blows the whole budget. You take one normal-length WhatsApp call and you're done for the day. The cap starts feeling punishing, and people churn out of the app within 3 days.
Below 20 minutes, the cap also stops being meaningful as a behavioral signal — it just becomes a hardware-block. The mental model shifts from "I'm budgeting my phone use" to "my phone is broken." Different psychology, different (worse) outcomes.
30 minutes is the smallest number that still allows for one normal real interaction per day (a call, a maps lookup that takes longer than expected, a banking app that has to be navigated) without immediately hitting the wall.
The other minimalist apps let you pick. They have to: their pitch is "you're in control."
Ours is the opposite. You're not in control. That's why you installed this.
If you could pick the number, you'd pick the number that lets you keep doing what you're doing. We know this because every screen-time app already lets you pick, and the average user picks something close to their current usage. That's not behavior change. That's permission.
The single fixed number takes that lever away. You either accept 30 or you don't install. If you don't accept 30, this isn't the app for you, and that's fine — there are dozens of customizable screen-time tools you'll find more comfortable. (Whether they'll work for you is a different question.)
In practice, 30 minutes a day buys you:
— Two to four short navigation sessions (Maps, route checking)
— A few brief banking / payment / wallet interactions
— One real "leisure" use, like reading something for ~5 minutes, OR a short messaging session
— Whatever else is in your six (calls and texts always work, those don't count)
That's a full day's normal phone use for someone who's not on it constantly. It's also, for someone coming from 4+ hours a day, an enormous compression. You'll feel it. You're meant to.
By week 2, you'll find you don't even hit the cap. The reach is gone. That's the whole point. The number was never about the number — it was about the reach.