With the app in English, volumes are in fluid ounces by default; you can switch to metric in Settings. Astras stores milliliters and converts only for display, so switching units never changes what you logged.
Water tracker
Water tracker and water reminder app with a home screen widget
Astras is a club. Your personal AI wellness assistant. Its water tracker logs what you drink in one tap: pick your glass once, tap plus for every glass, and watch the card fill toward a daily water intake goal set from your height, weight, sex and age. A home screen widget adds water without opening the app.
How the Astras water and hydration tracker works
Pick a size once
Under “Pick a size” there are six tiles. In US units: Sip 4 fl oz, Glass 8, Large glass 12 (the default), Small bottle 16.9, Bottle 24, Sports bottle 32. In metric: 100 to 750 mL. Choosing a tile only changes the portion; it logs nothing.
Tap + for every glass
Each tap adds the chosen portion, with a soft drop sound and a light buzz. “−” removes one portion and never goes below zero. You can go past your goal: the number shows what you really drank.
Watch it fill
The card reads “Water · today,” a large number like “48 / 72 fl oz” and “24 fl oz to go,” and water rises across the card with moving waves. At the goal it says “Daily goal reached,” and once a day a watercolor picture celebrates it.
Log from anywhere
The same card sits on Home and in the Nutrition tab; with Karina AI, “I drank a glass of water” in the chat logs it too.
How Astras calculates your daily water intake
Your goal comes from a formula, step by step:
Weight used
Your weight, moved into the healthy-weight range for your height (body mass index 18.5–24.9; 23–27 from age 65). So the goal follows the body your height suggests instead of climbing with extra weight or dropping too low for a very light one. No weight entered: the middle of the range. No height: your actual weight.
Milliliters per kilogram
By sex and age: women 31 under 55, 29 at 55–64, 27 from 65; men 35, 32 and 30.
Pregnancy mode
Adds 300 mL.
Rounding
To the nearest 50 mL, kept between 1,500 and 3,000 mL.
US units
The goal is rounded to whole 8-oz glasses, so you see 72 rather than 71 fl oz.
With neither height nor weight in your profile, the goal is 2,000 mL for women and 2,500 mL for men.
Example
A 34-year-old woman, 5′5″ and 154 lb. The healthy range for her height is about 111–149 lb, so the formula uses 149 lb (67.8 kg). 67.8 × 31 = 2,101 mL, rounded to 2,100 mL — about 8.9 glasses, so the goal becomes 9 glasses: 72 fl oz.
At the same height and 128 lb (58 kg): 58 × 31 = 1,798 → 1,800 mL → 8 glasses, 64 fl oz, half a gallon. In pregnancy mode, the first goal becomes 2,400 mL → 80 fl oz.
This is a general daily guide, not a medical norm. Heat, exercise and illness change what you need. If a doctor has told you to limit or increase fluids, follow that and set your own goal.
Set your own daily goal
Tap the gear on the water card to open “Daily goal.” “−” and “+” move it one 8-oz glass at a time (100 mL in metric), and quick goals set 48, 64, 96 or 128 fl oz — the last two are three-quarters of a gallon and a gallon. “Your own goal wins over the calculated one and is saved”: there’s no Save button to forget. “Calculate from my profile” brings back the formula. Your goal can be anywhere from 800 to 5,000 mL, and it’s used everywhere — the widget, the history, reminders and Karina AI’s answers.
Water reminder app: when Astras reminds you
- Four reminders a day at 9 AM, 1 PM, 5 PM and 9 PM, local time: “A little pause,” “Afternoon check-in,” “The evening is near” and “Round off the day.”
- Smart notifications, on by default: once you reach your goal, the rest of today’s reminders are skipped.
- Manual mode: turn smart notifications off and set “Drink water” on or off yourself.
- Your own times: with Karina AI, ask “remind me to drink water at 11 am.” It appears in Settings under “My reminders,” where you can switch it off or remove it.
Reminders run in the phone app and only when your plan includes water.
Water intake widget for iPhone and Android
- Two sizes. Small shows water; Medium shows water and “Snap a meal” side by side.
- The water tile shows today’s amount, “of 72 fl oz” and a water level. Three keys — 4, 8 and 16.9 fl oz (100, 250 and 500 mL in metric) — add water right on the home screen, without opening the app. Tapping elsewhere on the tile opens the water card.
- Not on the lock screen, so a person holding your phone doesn’t see it. The one exception: iPhone StandBy shows the small widget while charging.
- Offline by design. The app hands the widget ready numbers; on a new day, until you open the app, it says “These are yesterday’s numbers — open the app to refresh.”
- Adding it. Touch and hold an empty spot on the home screen, tap the plus (iPhone) or “Widgets” (Android) and find Astras. Choose what goes in each slot in Settings → “Home screen widget,” with a live preview.
Widgets live on phones; the web version has the water card only.
Water history
The Nutrition tab has “Water balance”: bars for the last 7, 14 or 30 days, the average, and min, max and median. Pick any day to see its total. History and removing water stay open even without a plan.
Privacy
Your water diary is part of your Astras account, so it’s the same on your phone and at astras.club. No ads in the app; we don’t sell your data for money; ad measurement runs only after you allow it, in every country (California law counts it as “sharing” and a “sale”). When you use Karina AI, your food and water diary for the last 7 days goes with your question so the answer can use it — only after you allow it on the permission screen shown before the first chat. You can export your data or delete your account in Settings.
Frequently asked questions
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There is no single number for everyone, so Astras calculates one from your profile. It takes your weight within the healthy range for your height, multiplies it by a rate for your sex and age, adds 300 mL in pregnancy mode, and keeps the result between 1,500 and 3,000 mL. For a 5′5″, 154 lb woman of 34 that’s 72 fl oz; at 128 lb it’s 64 fl oz. Treat it as a daily guide: hot weather, exercise and illness raise your needs, and a doctor’s instructions about fluids always come first. You can set your own goal at any time.
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Because 64 fl oz — eight 8-oz glasses — is one fixed rule, while Astras starts from your height, weight, sex and age. The formula gives a milliliter value, and with US units the goal is rounded to whole 8-oz glasses, so 2,100 mL becomes 9 glasses, or 72 fl oz, instead of an odd 71. Rounding the goal itself, not just the label, means a day can actually be completed. If you prefer 64 fl oz, open “Daily goal” and tap the 64 quick goal; your own goal wins over the calculated one.
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Yes. The water tile of the Astras widget has three keys — 4, 8 and 16.9 fl oz, or 100, 250 and 500 mL in metric — and each tap adds that amount on the spot, without opening the app. The app picks up the additions and logs them in the same diary as the card. The number on the tile changes right away. Water added to a day that has already passed is dropped, so yesterday’s total can’t change by accident. Tapping the tile outside the keys opens the water card in the app.
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It works on both iPhone and Android home screens, in Small and Medium sizes. On Android 12 and later it appears with your saved choice right away, and you can reconfigure it with a long press or from the app’s settings. It isn’t shown on the lock screen on either platform, because anyone holding the phone would see it. The exception is iPhone StandBy: while the phone charges on its side, the small widget is visible. The web version has no widget.
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The standard water reminders come at four fixed times — 9 AM, 1 PM, 5 PM and 9 PM in your local time zone — and the times themselves can’t be edited. What you can change: leave smart notifications on, and reminders stop for the day once you reach your goal; turn them off, and you decide whether “Drink water” reminders come at all. For a time of your own, ask Karina AI, if your plan includes it — “remind me to drink water at 11 am” — and the reminder appears in Settings under “My reminders.”
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No, Astras logs water volume only. There are no drink types, caffeine or calories in the water tracker — just the amount you add. If you want a cup of tea to count toward your water goal, you can add it as a portion, but the app won’t distinguish it from water. Drinks with calories, such as juice or a latte, belong in the food diary, where Astras counts calories from a photo, a voice note or text — see calories from a photo.
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No. Water is logged in Astras only: on the card, in the widget and through Karina AI, and it lives in your Astras account. Astras reads steps and active calories from Apple Health or Health Connect with your consent, but it doesn’t read or write water intake there. If another app logs your water in Apple Health, those entries won’t appear in Astras, and Astras entries won’t appear there. Your water diary is included when you export your data from Settings.
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Yes. When pregnancy mode is on, Astras adds 300 mL to your calculated daily goal before rounding. In the example above, 72 fl oz becomes 80 fl oz — ten 8-oz glasses. If you set your own goal by hand, Astras keeps your number and doesn’t add anything to it. The rest of the formula — weight within the healthy range, a rate by age, the 1,500–3,000 mL limits — stays the same. Pregnancy mode also changes your calorie target and turns the cycle calendar into a pregnancy calendar.
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No. Logging water is part of Astras Start and every larger plan, and plans start at $4.99/month (see pricing). Without a plan you can still see today’s total, the “Water balance” history and remove water you logged; adding new water opens a “plan needed” window. The widget itself and the app’s themes are never locked, and steps, the step leaderboard and meditations are free for everyone. Subscriptions bought in the app are managed in your App Store or Google Play account.
One tap for every glass
A daily goal from your height, weight, sex and age, and a widget on your home screen.