Humans cannot intuitively grasp large numbers. Psychology research confirms what we feel instinctively: "27 years old" is abstract, floating somewhere in the middle of a fuzzy timeline. But "10,000 days"? That's concrete. Countable. Graspable.

I built Days as Numbers because I wanted that feeling of concreteness without the morbidity of traditional mortality reminders. Here's the story.

The Inspiration

It started with a tweet I can't find anymore. Someone pointed out that 10,000 days is roughly 27 years and 4 months—and suggested celebrating it as a "metric birthday." The idea stuck with me.

There's something profound about reframing age in days. Years encourage us to think in chapters: your twenties, your thirties, mid-life. Days encourage you to think in moments. Every single day counts because you can count every single day.

In South Korea and Japan, the 10,000-day milestone is celebrated as "Peak Youth"—enough experience to be an adult, enough energy to embrace life fully. That cultural touchpoint resonated with me.

Why Days Hit Different Than Weeks

Tim Urban's famous "Your Life in Weeks" essay spawned an entire category of life-visualization apps. Week grids are powerful—seeing your remaining weeks as empty boxes is sobering.

But weeks have a flaw: they're still grouped. They still feel manageable in a way that distances you from the present moment.

Days are different. A day is the smallest unit we actually live in. You wake up, you do things, you go to sleep. One day. Tomorrow is another. There's no hiding from the granularity.

When I see that I'm 11,847 days old, I don't think about decades. I think about today being day 11,848. What am I going to do with it?

A Gentler Memento Mori

The "memento mori" movement—remember that you will die—has exploded in recent years. Stoicism apps remind you of mortality with skull icons and countdown timers. Some people find this motivating. I found it unnecessarily grim.

The New York Times framed age-in-days as "enough of a memento mori to light a fire under you, without being unnecessarily grim." That's exactly the balance I wanted.

Days as Numbers isn't about death. It's about awareness. It's about making the abstract passage of time feel tangible without making you anxious about it.

The number goes up every day. That's not depressing—that's living.

Design Philosophy: Radical Simplicity

The app does one thing. When you open it, you see your age in days. That's it.

No streak counters. No gamification. No notifications pestering you to "reflect on your mortality." No subscription upsells. No social features trying to make you share your day count with friends.

Just a number.

This was intentional. In a world where 86% of Gen Z is actively trying to reduce screen time, I wanted an app that respects your attention. Glance at it, recalibrate your perspective, move on with your life.

The design mirrors the philosophy: minimal interface, maximum impact.

// The core of the app is embarrassingly simple
func daysAlive(since birthdate: Date) -> Int {
    let calendar = Calendar.current
    let components = calendar.dateComponents([.day], from: birthdate, to: Date())
    return components.day ?? 0
}

The code is simple because the concept is simple. No complexity was added for complexity's sake.

Building with React Native and Expo

I chose React Native with Expo for a practical reason: I wanted to ship to iOS without learning Swift from scratch. Expo's managed workflow let me focus on the product, not the build system.

The app has almost no state to manage. You set your birthdate once, and the app calculates your day count from that. No server, no sync, no accounts.

// The entire app state
interface AppState {
  birthdate: Date | null;
  onboardingComplete: boolean;
}

Navigation uses Expo Router, which mirrors the file-based routing I'm used to from Next.js. Two screens: onboarding and the main day display. That's the entire app.

EAS Build handles the App Store submission pipeline. Push a commit, get a build. No Xcode required (mostly).

The Milestone Moments

One feature I'm particularly proud of: milestone celebrations. The app highlights when you're approaching significant day counts:

Days	Approximate Age	Milestone
10,000	27 years, 4 months	Peak Youth
15,000	41 years	Prime Wisdom
20,000	54 years, 9 months	Golden Age
25,000	68 years	Distinguished
30,000	82 years	Legendary

These aren't arbitrary. 10,000 is mathematically satisfying. Each milestone after represents roughly another decade and a half of living.

When you're within 100 days of a milestone, the app shows a subtle indicator. Not a pushy notification—just a quiet acknowledgment that something interesting is approaching.

What I Learned Building It

Start with your own need

I built this app because I wanted it. Not because market research suggested it. Not because there was a gap in the App Store. Because I personally wanted to see my age in days every morning.

That authentic need shaped every decision. The simplicity, the lack of notifications, the one-screen design—all came from solving my actual use case.

Resist feature creep

The temptation to add features is constant. What about a widget? What about Apple Watch support? What about a journal feature? What about sharing?

Every feature request got filtered through one question: does this serve the core purpose of making time feel tangible?

A widget? Yes—that makes the day count even more accessible. (It's on the roadmap.)

A journal? No—that's a different app. Go use Day One.

Pricing for indie apps is emotional

I agonized over pricing. Free with ads? Free with premium? One-time purchase?

I landed on a simple one-time purchase. No ads (they'd ruin the minimalist experience). No subscription (for an app this simple, that feels predatory). Just a fair price for a thoughtful tool.

The App Store takes 30%, which stings. But the alternative—building my own payment system, managing accounts, handling billing support—would have killed the simplicity.

The Launch

I soft-launched Days as Numbers with zero marketing budget. No Product Hunt launch. No Twitter thread. Just submitted to the App Store and told a few friends.

The response was quiet but meaningful. People who found it tended to love it. The reviews aren't numerous, but they're genuine.

One user wrote: "I check this every morning. It's the only app that makes me feel like today matters without making me feel anxious about tomorrow."

That's exactly what I was going for.

The Road Ahead

Days as Numbers is feature-complete for its core purpose. But there are a few additions I'm considering:

Widgets for home screen and lock screen
Apple Watch complication showing your current day count
Custom milestones for personal significant numbers
Optional gentle notifications for milestone approaches

Nothing that compromises the simplicity. Just small enhancements that serve the core purpose better.

The Deeper Point

We measure everything in our lives. Steps walked. Calories consumed. Hours slept. Money saved.

But we rarely measure the most fundamental thing: days lived.

Days as Numbers isn't really about productivity or self-improvement. It's about perspective. It's about occasionally pausing to acknowledge that today is one day out of your finite allotment, and that's neither depressing nor motivating—it's just true.

10,000 days is not a lot. It's also not a little. It's exactly enough to do something meaningful with.

What will you do with day 10,001?

Try It Yourself

Days as Numbers is available on the App Store. Simple, private, no account required.

Download Days as Numbers | View on the App Store

Building something simple is harder than building something complex. If you're working on a minimalist app and want to talk through the design decisions, reach out on GitHub or Twitter/X.