Happy Scale is a mature, local-first trend app. It imports one weight per day from Apple Health, the lowest, while Trendline keeps every reading with its timestamp, source, and unit. Trendline's annual and lifetime plans cost less at current U.S. prices; Happy Scale has a lower monthly price and a free tier.
Trendline is an iPhone app that reads Apple Health. If you're here because you want Happy Scale on Android: Happy Scale lists no Android version, and Trendline is iPhone-only. Libra Weight Manager is a long-running weight-trend app that does, and it has an iPhone version too. Everything below is iPhone territory.
First, the honest part
Happy Scale has earned its reputation: a 4.9-star average across roughly 58,000 App Store ratings, first released in 2012 and still updated in September 2026, local-first storage with no vendor account, and two-way Apple Health support: it imports your weights and can export them back (its App Store listing and support FAQ, checked October 2026). Its core idea — show a smoothed moving average so one salty dinner can't ruin your morning — is the same measurement literacy Trendline is built on. If you want exactly that, well-executed, you can stop reading and be in good hands.
The one design choice to understand
When it imports from Apple Health, Happy Scale takes one weight per day: the lowest entry. Its FAQ says it "will import the lowest weight entry, as this is the best way to estimate your moving average" (Happy Scale support FAQ). That is a legitimate, documented modeling decision, and for many people it's fine.
Trendline makes the opposite choice: every reading is kept, with its timestamp, source, and unit. Nothing about your day is discarded or selected. Two consequences follow. Practically, morning and evening readings, multiple sources, and dense histories all survive intact. Epistemically, the trend is computed from what actually happened rather than from a per-day selection rule — and when your data is sparse, Trendline says the evidence is thin instead of drawing an equally confident line. The full math is public on the methodology page.
Where the two apps genuinely differ
| Happy Scale | Trendline | |
|---|---|---|
| Daily readings | One per day imported (lowest), per its FAQ | Every reading kept, with provenance |
| Trend method | Four smoothing methods to choose from, including exponential smoothing and a seven-day moving average, per its FAQ | Statistical trend with explicit uncertainty; declines to conclude when evidence is sparse |
| Writes to Apple Health | Optional: exports all weights | Only after an explicit action for that exact operation |
| Energy (TDEE) | Not documented | Not in the current iPhone app; a separate free browser calculator is available on this site |
| Composition metrics | Weight-focused, with a BMI calculator; body fat not documented | Manual entry for composition values beyond Apple Health's types (visceral fat, body water, muscle mass…) |
| Accounts and sync | None required; local-first, with optional Dropbox sync | None required; Apple Health is the only "account", and Trendline runs no iCloud sync service |
| Devices | iPhone and iPad; the listing also shows Apple-silicon Mac compatibility | iPhone only |
| Pricing | Free download; Deluxe $1.99/mo or $11.99/yr; lifetime $39.99 (App Store listing, October 2026) | $0.99/week · $3.99/month · $10.99/year · $34.99 lifetime |
Trendline's annual and lifetime plans cost less than Happy Scale's paid equivalents at the U.S. prices above; Happy Scale's monthly plan costs less, and it also offers a free tier. The product differences matter too: Trendline keeps every reading rather than one per day, treats Lose/Build/Maintain as distinct phases, adds body-composition context, and shows a trend that states its uncertainty. Choose the approach that fits how you track.
Who should pick which
- Pick Happy Scale if you want a mature, single-purpose trend tracker with a choice of smoothing methods, love its milestone and prediction features, want it on your iPad too, and one reading per day matches how you weigh.
- Pick Trendline if you keep multiple readings or sources, want the trend to admit uncertainty, want losing, building, and maintaining treated as different jobs, or want your scale's composition estimates kept in context.
Try the idea
The core disagreement — what a trend should do with your raw readings — is testable right now: paste your weights into the free weight trend calculator and see the slower signal drawn against every single reading, nothing discarded.
Questions people ask
Is Happy Scale good?
Happy Scale has earned its reputation: a 4.9-star average across roughly 58,000 App Store ratings, first released in 2012 and still updated in September 2026 (its App Store listing and support FAQ, checked October 2026). If it fits you, use it.
Does Happy Scale import every weight from Apple Health?
No. It imports one weight per day, the lowest entry. Its FAQ says it "will import the lowest weight entry, as this is the best way to estimate your moving average" (Happy Scale support FAQ).
Is there a Happy Scale for Android?
Happy Scale lists no Android version, and Trendline is iPhone-only. Libra Weight Manager is a long-running weight-trend app that does run on Android, and it has an iPhone version too.
How much does Happy Scale cost?
Happy Scale is a free download, with Deluxe at $1.99 a month or $11.99 a year, or a lifetime unlock at $39.99 (App Store listing, October 2026). Trendline's annual and lifetime plans cost less at current U.S. prices; Happy Scale's monthly plan costs less.
Should I pick Happy Scale or Trendline?
Pick Happy Scale if you want a mature, single-purpose trend tracker with a choice of smoothing methods, want it on your iPad too, and one reading per day matches how you weigh. Pick Trendline if you keep multiple readings or sources, want the trend to admit uncertainty, or want your scale's composition estimates kept in context.
Sources
- Happy Scale on the App Store (version 2026.7: pricing, devices, Health export, ratings)
- Happy Scale support FAQ (one-weight-per-day import, smoothing methods, storage and Dropbox sync)
Trendline is not affiliated with or endorsed by Happy Scale or Front Pocket Software. Facts above were verified against the linked pages on October 3, 2026; app stores change — check the listing for current pricing.