B2C · science-based fitness coaching app
How Built With Science grows
21 tactics and 22 figures from 1 interview.
A fitness coaching app built on a YouTube channel of about 3M subscribers, Built With Science turned its workout course into an app, launched it to that audience, then spent a year improving trial-to-paid and retention before buying any ads. Growth since then has come mainly from in-house Meta ads that do not rely on the creator, sent to a long quiz on its website, alongside YouTube videos and free tools.
- Built With Science started Meta ads in January 2026 and the host put it at about $100K a month since, using B-roll, testimonials and AI static ads; Meta trials convert to paid at about 25%, against 35-40% organic.Built With Science (1)Built With Science (2)Built With Science (3)
- About 90% of ad traffic goes to a long personal quiz on the website, which converted much better than sending clicks to the App Store; the same quiz inside the iOS app did worse.Built With Science
- Showing only the yearly plan first, with a day-by-day trial timeline and reminder promise, moved annual picks from about 60% to 75-80% with no price change; about 15% of trial starts add a gym buddy at 15% off each.Built With Science (1)Built With Science (2)
- The team says about 70% of tests fail the first time: a pay-now discount that made the trial sound worse lost, and more pricing-page text hurt conversion, but reframing both options as good choices showed a strong early lift.Built With Science (1)Built With Science (2)Built With Science (3)Built With Science (4)
- On YouTube, the app gets a soft mention mid-video; click tracking per video showed stories of users transforming their bodies bring more trials than broad educational videos, and hired clippers repost clips to Reels and TikTok.Built With Science (1)Built With Science (2)
- The app has cost about $189 a year since launch, pitched as a personal trainer in your pocket rather than a tracker; free calorie and macro calculators built for AI search also lead into the quiz.Built With Science (1)Built With Science (2)
Summary written 2026-09-26 from the tactics below. Figures are as founders stated them.
About Built With Science
- What it is
- Personalized workout and nutrition app with AI coaching, built on Jeremy Ethier's fitness YouTube channel
- Who it's for
- People wanting research-backed training and nutrition guidance, largely from Jeremy Ethier's YouTube audience
- Business model
- subscription with free trial, sold mainly through a web quiz funnel
- Pricing
- about $189/year or $30/month; 14-day free trial; tested: pay upfront with no trial for 20% off, with 30-day money-back guarantee; gym buddy plan: both users get 15% off
- Launched
- early January 2025
- Team
- Internal content team, product managers, in-house engineers; Meta ads run in-house
As described in the interviews, not independently verified.
Built With Science's 21 tactics
Built With Science by the numbers
| Metric | Value | Context | Said in |
|---|---|---|---|
| users | 100K users approximate | People who joined the web-based courses before the app | Sub Club by RevenueCat 2026-09-02 |
| followers | 1M subscribers approximate | YouTube subscribers when they decided to build the app | Sub Club by RevenueCat 2026-09-02 |
| followers | +1M subscribers/year approximate | YouTube subscriber growth per year | Sub Club by RevenueCat 2026-09-02 |
| followers | 3M subscribers approximate | YouTube subscribers at app launch | Sub Club by RevenueCat 2026-09-02 |
| followers | 7M subscribers approximate | YouTube subscribers now | Sub Club by RevenueCat 2026-09-02 |
| ad spend | USD 100K/month approximate | Meta ad spend, scaled from zero in 2026, described by host as profitable | Sub Club by RevenueCat 2026-09-02 |
| time to milestone | 1 months approximate | Time to get a Meta trial-to-paid baseline before scaling spend | Sub Club by RevenueCat 2026-09-02 |
| share | 90% approximate | Share of (paid) traffic sent to the website quiz rather than the App Store | Sub Club by RevenueCat 2026-09-02 |
| price | USD 189/year approximate | Annual plan, unchanged since launch | Sub Club by RevenueCat 2026-09-02 |
| price | USD 30/month approximate | Monthly plan | Sub Club by RevenueCat 2026-09-02 |
| conversion rate | 15% approximate | Share of trial starts who add a gym buddy to their plan | Sub Club by RevenueCat 2026-09-02 |
| price | 15% | Discount each user gets on the gym buddy two-person plan | Sub Club by RevenueCat 2026-09-02 |
| conversion rate | 35–40% approximate | Trial -> paid for warm organic traffic from YouTube | Sub Club by RevenueCat 2026-09-02 |
| conversion rate | 25% approximate | Trial -> paid for Meta ad traffic | Sub Club by RevenueCat 2026-09-02 |
| share | 75–80% approximate | Share of subscribers choosing the annual plan, after the annual-first pricing page experiment | Sub Club by RevenueCat 2026-09-02 |
| share | 60% approximate | Share choosing annual before the pricing page experiment (60/40 annual/monthly) | Sub Club by RevenueCat 2026-09-02 |
| share | 85% approximate | Host's recap of annual share after the experiment; conflicts with guest's 75-80% | Sub Club by RevenueCat 2026-09-02 |
| share | 30–40% approximate | Share of traffic historically coming from SEO (old blog posts), since declining with AI search | Sub Club by RevenueCat 2026-09-02 |
| share | 70% estimate | Share of experiments that fail on the first attempt | Sub Club by RevenueCat 2026-09-02 |
| count | 100 users approximate | Core beta group of former web-course members | Sub Club by RevenueCat 2026-09-02 |
| count | 1,000 users approximate | Wider beta tester pool | Sub Club by RevenueCat 2026-09-02 |
| price | 20% | Discount for paying upfront with no trial (vs 14-day free trial), in a paywall test | Sub Club by RevenueCat 2026-09-02 |
Topics
Meta ads for apps (Facebook and Instagram)5SEO and content marketing4YouTube marketing for apps4Pricing a subscription app4App paywall strategy4Founder-led marketing and building in public3Attribution and ad signal engineering3Personalization in onboarding and paywalls2Web-to-app funnels and web checkout2Activation: getting users to first value2
Interviews
- Scaling Meta Ads from zero to $100K a month — Ethan Ethier, Built With Science · Sub Club by RevenueCat · 2026-09-02