Connect · auto-log every session · zero backend

Log every workout automatically.
Ten-minute setup. Once.

SweatSciences reads your workout duration and body weight from Apple Health (or any smart scale synced to it). You run a shortcut after class; your formula computes; the session lands in your workout log. No account, no subscription, no native app — just an Apple Shortcut talking to your browser's local storage.

iOS · recommended

Apple Shortcuts + HealthKit

Full auto-log. Reads workout + weight from Health. Build-it-yourself steps below — about 10 min one-time.

Android

Google Fit / Health Connect

Coming later. For now, use the manual calculator; HealthKit is the Phase-0 integration.

Any · fallback

Quick-log bookmarklet

Drag to bookmarks; click after class to prompt for weights and auto-fill the calculator. Works on any browser.

The Apple Shortcut — step by step

We can't host the shortcut file (would require an iCloud account to upload and a per-user token system). It's a one-time 10-minute build. Once it's on your iPhone, it runs in about 3 seconds after each class.

What you'll need

iPhone with the built-in Shortcuts app · Apple Health with workout history (Apple Watch, Oura, Whoop, any tracker that syncs) · A smart scale synced to Health (Withings, Renpho, Eufy, etc.) — optional but makes it fully automatic

1

Open the Shortcuts app · tap  +  to create a new shortcut

Name it "Log SweatSciences Session".

2

Add action: Find Workouts

Search for "Find Workouts" in the action list. Set: Sort by Start Date · Order Latest First · Limit: 1.

This grabs your most recently ended workout from Apple Health — whether it's a Watch-detected workout, a manual entry, or synced from a third-party app. You can filter by activity type (e.g., "Yoga") if you want to restrict it.
3

Get the Duration from that Workout

Add "Get Details of Workouts" → set the Detail to Duration. Save to a variable named duration_sec.

We'll convert this to minutes in the URL-builder step.
4

Find your Body Mass samples (last 24 hours)

Add "Find Health Samples" → set Type: Body Mass, Order: Latest First, Limit: 2.

If you use a smart scale that syncs to Health, the two most-recent readings are typically your before-class and after-class weights. If you only have one reading, we'll prompt you to weigh in now.
5

Pull the two weights

Use Get Item from List twice — first item = weight_after (most recent), second item = weight_before. Then Get Details of Health Sample → Value for each. Health stores weight in your preferred unit (lb or kg). If kg, multiply by 2.20462 to get lb.

6

(Optional) Prompt if you didn't step on the scale after class

Add "If" action — if weight_after is empty or less than 10 minutes old, use it; otherwise show "Ask for Input" with prompt "Weigh in now — what's your weight? (lb)".

7

Build the URL

Add "Text" action with this template. The tokens in orange get replaced by your Shortcut variables.

https://sweatsciences.com/?m=p&wb={weight_before}&wa={weight_after}&wd=0&s=1100&auto=1#calc
m=p = precise (weigh-in) mode — the calculator computes your loss straight from the weight delta · wb = weight before (lb) · wa = weight after (lb) · wd = fluid drunk during class (oz; 0 if none) · s = how salty you sweat (800 light → 1,800 very salty; 1,100 is average — adjust once and it sticks) · auto=1 = compute and save to your log automatically.
8

Add Open URL at the end

Pass the built URL to "Open URLs". Done. The browser opens to the calculator with everything pre-filled. It computes your formula, saves the workout to your local log, and you see your recipe.

9

(Optional) Add to Apple Watch + Automation

Back on the main Shortcut screen, tap the share icon → "Show in Share Sheet". You can run it from Apple Watch too. Or: open Shortcuts → Automation → Create Personal Automation → When Workout Ends → add "Run Shortcut: Log SweatSciences Session." Fully automatic after every workout.

That's it

First-time setup: ~10 minutes. Every session after: zero friction. The data lives in your browser (no account needed). Your workout log at sweatsciences.com/workouts fills up automatically.

Or — the 30-second bookmarklet (any browser)

No iPhone or don't want to build a shortcut? Drag the button below to your bookmarks bar. After each class, click it; it asks for your weights + duration and opens the calculator pre-filled.

⬛ SweatSciences Quick-Log

How to install the bookmarklet

On desktop: drag the blue button into your bookmarks bar.

On mobile: tap-and-hold the button → "Add Bookmark." Then just tap the bookmark anytime to log a session.

Privacy + what we actually see

Nothing leaves your device. The Shortcut sends your weights + duration to the SweatSciences URL as query parameters, which our JavaScript reads and processes entirely in your browser. Your workout log is stored in your browser's localStorage — we do not have a server that holds any of it. Export / backup via the Export JSON button on the Workouts page.

When we ship account sync later (Phase 1), you'll opt in explicitly and your data gets encrypted. Until then, this is the most private possible integration — your HealthKit data never touches a cloud we control.

What's coming after Phase 0

Phase 1

Strava OAuth

For runners + cyclists who don't use Apple Watch. Covers Android too via web OAuth.

Phase 1

Studio partner API

Mindbody / ClassPass integration — your class duration + room temp come in automatically from the studio's schedule.

Phase 2

Native iOS app

Apple Watch complication for "log last workout." Background-syncing. Ships when the roadmap supports the build.