Tools
The LifeWell tools module is a set of stateless calculators and timers that run entirely in the browser (or app, on mobile). Type your inputs, get a result. Nothing is saved to your profile unless you explicitly tap "Save" — these are reference utilities, not tracking surfaces. The result is the result; come back tomorrow with new inputs and the calculator runs again.
This page is the index. Each entry below links to a dedicated page that covers the formula, the cited source, the inputs and outputs, a worked example, and the limits of what the tool can claim.
Calculators
| Tool | What it computes | Cited source |
|---|---|---|
| BMI calculator | Body Mass Index from weight + height | WHO BMI classification |
| BMR calculator | Basal Metabolic Rate (kcal/day at rest) | Mifflin-St Jeor (1990); Harris-Benedict (1919, revised 1984) |
| Calorie calculator | Daily calorie target adjusted for goal | Mifflin-St Jeor + activity multiplier + deficit/surplus |
| TDEE calculator | Total Daily Energy Expenditure | BMR × activity multiplier |
| Macro calculator | Protein / carbs / fat grams per day | Diet-preset percentages + 4/4/9 cal/g |
| Protein calculator | Daily protein target in grams | Goal × activity × body weight (g/kg) |
| Age calculator | Exact age in years/months/days + extras | Calendar arithmetic |
Timers
| Tool | What it does | Range |
|---|---|---|
| Sleep tracker | Log nightly duration + quality (separate from /health/sleep) | 0–24 hours |
| Step counter | Manual step-count log (no pedometer integration) | 1–100,000 steps |
| Interval timer | Configurable work/rest interval timer | Custom seconds |
| Workout timer | Multi-round configurable workout timer | 5–300 min sessions |
| Kegel trainer | Pelvic-floor squeeze/release timer | 1–100 reps per session |
What they share
Every tool follows the same conventions:
- Inputs validated — out-of-range values get rejected at the form.
- Result inline — no navigation between input and output.
- Citation visible — the formula's named source is on the page.
- No persistence by default — using a calculator does not write anything to your profile unless you tap "Save".
- Honest framing — every page lists what the result is and isn't.
How they differ from health-module tracking
The /health/* surfaces (vitals, water, medications, sleep, etc.) are logs — every interaction is persisted, charted, and aggregated. The /tools/* surfaces are calculators and timers — typically one-off uses that don't need a history.
A few of the timers (workout-timer, kegel-trainer) do save a session entry to a Zustand-backed store when you complete one — that's the only crossover. The calculators are stateless.
When to use which
- "What's my BMI?" → BMI calculator
- "How many calories should I eat to lose weight?" → Calorie calculator (sets a deficit on TDEE)
- "How much protein should I eat?" → Protein calculator
- "What macros for keto?" → Macro calculator with the keto preset
- "How many calories do I burn just by being alive?" → BMR calculator
- "How many calories do I burn with my activity level?" → TDEE calculator
- "Set up a Tabata-style timer" → Interval timer
- "Time a 45-minute strength workout" → Workout timer
- "Walk through a kegel session" → Kegel trainer
- "Calculate exact age from a birthday" → Age calculator
Frequently asked
Do these calculators store my inputs? No. Inputs and outputs are session-local and disappear when you close the page. The timer surfaces save a session record when you complete one (so the dashboard active-minutes total is accurate), but the calculator surfaces are stateless.
Are the formulas medical-grade? They're the standard formulas published by the cited sources — accurate as a general reference. Individual variation can be significant (5–15% on BMR, more on calorie target). For clinical work, a registered dietitian or physician using indirect calorimetry will give you a tighter number.
Can I use the timers without logging? Yes — the workout and kegel timers can run without saving a session at the end (skip the "Save" tap and close the page). The interval timer is purely a timer with no log.
Are these tools available offline? Yes. The calculators run client-side, the timers run client-side. The only network call is when you save a session record (which queues for offline sync — see Offline-first design).
Where to read next
- BMI calculator — the most-used tool, starting point.
- TDEE calculator — the basis for the calorie and macro calculators.
- Health module — for logging, not calculating.
Last updated: 2026-05-11 Author: Ahsan Mahmood
:::note Health information — not medical advice LifeWell and this documentation are provided for general wellness and educational purposes only. They are not a substitute for professional medical advice, diagnosis, or treatment, and nothing here is intended to diagnose, treat, cure, or prevent any condition. Always consult a qualified healthcare professional with questions about your health, and never disregard or delay professional advice because of something you read here. In an emergency, contact your local emergency services. :::