Lose Weight
See whether the sustained direction is down—even when today is up. A +2.1 morning stays a morning; the week keeps its verdict.
Explore losing with less noise →TRENDS BEYOND DAILY NOISE
Your body changes slowly. Your scale doesn’t.
Trendline turns weight readings you enter yourself — or compatible measurements your scale’s app saves to Apple Health — into a calm story about the change that is actually holding.
Private by designWorks with the Apple Health appNo daily judgment
Fictional sample readings. No person’s health record is shown.
THE DEMONSTRATION
One week, read twice.
The same seven mornings — first the way the scale shows them, then the way Trendline reads them. Pick the job to see how the language changes with the goal.
Seven mornings, one scale. Tuesday, +2.1 — easy to read as failure. Every reading is an honest observation — and no single one of them says which way the week actually went.
Seven mornings, one scale. Tuesday, −0.6 — easy to read as a stalled bulk. Every reading is an honest observation — and no single one of them says which way the week actually went.
Seven mornings, one scale. Wednesday, +1.4 — easy to read as slipping. Every reading is an honest observation — and no single one of them says which way the week actually went.
The same seven mornings, read together: drifting down about 1.9 lb a week. That's an early read, not a verdict — with this much day-to-day movement, a direction usually takes 12 days or more to firm up.
The same seven mornings, read together: drifting up about 1.4 lb a week. That's an early read, not a verdict — with this much day-to-day movement, a direction usually takes 7 days or more to firm up.
The same seven mornings, read together: holding in a narrow range. That's an early read, not a verdict — with this much day-to-day movement, a direction usually takes 7 days or more to firm up.
Too few mornings to call a direction. The instrument says so — and waits.
Three readings scattered across three weeks. The honest answer: too few mornings to call a direction yet — so this page won't. The story arrives with the data.
Too few mornings to call a direction. The instrument says so — and waits.
Three readings scattered across three weeks. The honest answer: too few mornings to call a direction yet — so this page won't. The story arrives with the data.
Too few mornings to call a direction. The instrument says so — and waits.
Three readings scattered across three weeks. The honest answer: too few mornings to call a direction yet — so this page won't. The story arrives with the data.
Now read your own week →This demonstration uses example data and the same in-browser math as the free calculator. Nothing about you is measured here.
Two more free instruments, same rules — no signup, nothing uploaded:
TDEE Calculator →Goal Timeline →Own a smart scale? Start here →ONE STORY, THREE SEASONS
Change has a lifecycle.
Losing, building, and maintaining are different jobs. Trendline changes the story it tells so the same number does not mean the same thing in every phase.
Build Lean
Notice gradual gain while keeping body-composition estimates labeled as estimates — never invented physiology.
Explore deliberate growth →The missing phase
Maintain
Treat a stable range as success instead of expecting a perfectly flat line. Most tracking ends at the goal; Trendline treats what comes after as a first-class season.
Explore the missing phase →THE APP UP CLOSE
What a calm week actually looks like.
This is the maintenance dashboard, not a mockup of one. Three things worth noticing — none of them is a number telling you how today went.
The headline, above everything else
“You're in your range.” The app leads with an interpretation, not a measurement. During a cut the same line can read “Early read: steady loss. The cut is working.” The sentence changes because the phase and evidence changed—not because one reading gets the final word.
The Now card, and the words under it
Weight and body fat sit together and are stamped Paired session — they came from one weigh-in, so they are comparable. Readings that did not arrive together are not silently drawn as if they had.
The three-month tiles
The current reading is 189.9 lb inside an 188–192 lb range. Maintenance means a band, so movement is judged against that band instead of against a single target number.
A real screen from the app, running fictional sample readings. No person’s health record is shown.
INSIDE THE INSTRUMENT
Deterministic, inspectable — and willing to wait.
The same readings, focus, and settings always produce the same story. No generative model invents a health conclusion; when the evidence is thin, the only defensible output is a refusal.
Readings, in context
Apple Health weigh-ins and estimates — kept with their source, device, and cadence, under the focus you chose.
- Focus
- Sources
- Cadence
178.4 lb · smart scale + 2 manual · 18 sessions / 21 days
Deterministic trend logic
Separates day-to-day movement from sustained direction. Same inputs, same answer — every time, inspectable end to end.
deterministic trend fit · no generative model · window-aware
A story you can use
“Change is holding.” Direction, pace, and what today's reading does — and doesn't — mean for it.
−0.3 lb/wk sustained · today +0.8 vs trend · example
Or an honest refusal
“Not enough evidence yet.” Sparse or conflicting evidence earns cautious language, not a confident guess.
4 readings / 16 days → no verdict yet · example
WHAT TRENDLINE WON'T DO
What Trendline won't do
- No streaks.
- No guilt.
- No red numbers.
- No AI predictions.
- No daily judgment.
Just the direction that's actually holding — told honestly.
This website never receives your measurements. App-owned readings stay on your iPhone and may be included in its backup; Trendline does not send them to CloudKit or operate an iCloud sync service. How privacy shapes the product →
3free in-browser instruments
0bytes of your data uploaded
7day trial on eligible subscriptions
1lifetime option — renewals end
PRICING WITHOUT SURPRISES
Choose your plan. Eligible subscriptions start with seven days free.
Weekly, monthly, and annual subscriptions include a seven-day introductory trial when Apple confirms eligibility. Lifetime is a one-time purchase with no trial or renewal. The full app is available during a subscription trial, and every price below shows the math apps usually make you do yourself.
Weekly
$1.99/week
For a short, focused push — a cut, a bulk, a deadline. About $103 a year if you stay, and we'd rather show you that math than hide it.
Monthly
$5.99/month
About $72 a year. Month to month, cancel any time.
Annual
$39.99/year
About $3.33 a month — 44% less than paying monthly. The plan that assumes Trendline earns its place.
Lifetime
$99.99 once
Hate subscriptions? Own it forever. No renewals, ever.
Get launch details
Prices in USD; App Store pricing may vary by region. Apple confirms trial eligibility before purchase. Full details in the Terms.
STRAIGHT ANSWERS
The questions you're right to ask.
Another subscription? Really?
Fair. A subscription is what keeps the interpretation work funded — Health-format upkeep, new story logic, no ads, no data sales. But it isn't mandatory: Lifetime is a one-time purchase that ends renewals forever. Eligible weekly, monthly, and annual subscriptions include seven days free; Lifetime does not include a trial. The full price grid sits right above this answer.
Apple Health already shows my weight. Why do I need this?
Health stores readings; it doesn't tell you what they mean. Trendline reads those same readings and answers the question you actually have: is the change holding? One number on a Tuesday can't answer that. A sustained trend can.
Is my health data safe?
Apple Health readings are interpreted on your device. App-owned readings stay on your iPhone and may be included in its backup; Trendline does not send them to CloudKit or operate an iCloud sync service. Nothing is uploaded to this website, there are no ads, and we don't sell data.
My weight bounces around constantly. Won't a tracking app just stress me out more?
That bounce is exactly what Trendline exists to absorb. It separates day-to-day noise from the direction that's actually holding, so a salty dinner doesn't read as failure. Try the free Weight Trend Calculator on this site — you can feel the difference before you install anything.
I don't weigh in every day. Is that a problem?
No — and Trendline won't pretend otherwise. When readings are sparse, it says the evidence is thin instead of drawing a confident line through guesswork. Stated uncertainty is a feature, not an apology.
Is this medical advice?
No. Trendline is an interpretation tool, not a medical device, and it never diagnoses or prescribes. For goals affected by symptoms, medications, or medical history, a qualified professional is the right resource — and we'll keep saying that plainly.
BE THERE AT LAUNCH
See your own trend first.
Trendline is preparing for launch. Meanwhile, the free calculator runs the same kind of trend math in your browser — paste your weigh-ins and watch the week resolve.
Or see your own trend now →