Set your standard.

Your metabolism, measured. Never assumed.

Every calorie app starts you on a textbook equation. Kriterion starts there too, then stops trusting it as soon as it has better information: your own logged intake set against your own weight trend. That is the only honest way to know what you burn.

• It shows its confidence. The estimate carries a real 95% interval, so "1,870 ± 49 kcal" means what it says. When there isn't enough data yet, it tells you it is still calibrating instead of inventing precision.
• It weights recent data properly. The blend between the textbook figure and your measured one scales with how much you have actually logged. A patchy fortnight moves your target less than a diligent one, automatically.
• It knows water isn't fat. Weigh-ins taken during a creatine loading phase are excluded from the trend, because three pounds of water retention is not three pounds of progress, and an algorithm that can't tell the difference will quietly cut your calories for no reason.
• It plans forward. Blueprint runs from your baseline to a future plan to a roadmap, so a target is something you arrive at deliberately rather than something the app changes behind your back.

Logging food without losing your evening.

Photograph the nutrition panel and the numbers come straight off it. No hunting, no typing. Search a brand and you get real menu items with their provenance shown, rather than a thousand user-submitted guesses at the same sandwich.

• Read the label, not the database. The printed panel is the most reliable source of truth there is for a packaged food, so Kriterion takes the numbers from it directly. Barcodes work too, and anything logged once can be saved as a favourite, a meal or a whole recipe.
• Lab-analysed, not crowd-sourced. The food data comes from CoFID, the UK government’s own Composition of Foods Integrated Dataset, alongside USDA FoodData Central, Open Food Facts and 8,296 menu items pulled from 28 real UK chains: Greggs, Costa, Pret, Nando’s, Wagamama and the rest. Every entry is marked with where it came from, so you always know which figures were measured in a lab and which are somebody’s best guess.
• Over fifty nutrients, honestly reported. Kriterion tracks which nutrients a source actually measured, so a blank is shown as "not measured" rather than a dietary zero. That is the distinction most trackers quietly collapse.
• Guidance, not scolding. "911 kcal left, still room to go. Carbs is the one to watch" is the whole tone: what is true, and what to do about it.

Training that reads the room.

Kriterion checks your readiness before it suggests a session, keeps the numbers that actually drive progress, and notices the things you would rather it noticed for you.

• Readiness before effort. Sleep, recent load, fuelling and cycle phase combine into one honest read. "Train, but watch fatigue" is a more useful thing to hear than a motivational quote.
• A muscle coverage map. It will tell you your quads haven't been touched in eleven days, which is the sort of thing a training log should be for.
• The numbers that matter. Previous best in front of you as you lift, estimated 1RM, session volume, reps in reserve, and a personal record called the moment you set one.

A timer that talks, so you don't have to look.

Every interval is called out loud, and it keeps running with the screen off and your phone in your pocket. The one thing you cannot do mid-set is read a screen, which is exactly when most timers ask you to.

• Custom, EMOM, Tabata and Rep. Four modes rather than one, because an EMOM and a Tabata are not the same session with different numbers.
• Target heart rate zones. Aerobic, threshold and anaerobic, each with the actual BPM window worked out for you rather than left as a percentage to do in your head.
• It survives the lock screen. Backgrounded, screen dark, still counting and still speaking. That is a background audio permission the app actually declares and uses.

Built for women, not adapted for them afterwards.

Most fitness apps bolt the menstrual cycle on as a separate calendar. Kriterion treats it as an input. It changes your energy, your appetite and what a hard session costs you, so leaving it out makes the other numbers wrong.

Cycle phases are estimated from the dates you enter and are not a contraceptive method and not a fertility test. Kriterion is a wellness tracker, not a medical device. If your cycle changes unexpectedly, speak to a doctor or pharmacist.

• It asks about contraception, because it matters. The pill, an implant, a hormonal IUD or an injection substantially flattens the cycle that phase-based guidance assumes. Kriterion asks, and then shows you framing that fits your body rather than one that doesn't apply to it.
• Phase feeds readiness directly. It sits alongside sleep and fuelling in the daily score on your Today screen. On an ovulation day the app literally reads "lifted by Ovulation".
• It admits what it doesn't know yet. Before it will claim your training responds to your cycle, it says so plainly: that needs about three full cycles of logged data. No invented correlation from two weeks of use.
• Your accent, your app. Four brand colours, all balanced to one lightness band so none is the lesser version, and none reuses a hue that already means protein, carbs or fat.

One screen that is entirely you.

Every other screen is a tool. Snapshot is the answer: where you are now, what changed, and whether the last fortnight was typical. It even wears the accent colour you chose, because it belongs to you rather than to a feature.

• Fourteen days at a glance. Each bar is how much you logged that day across food, training, water and weight. Tap one to open it.
• Before and after, properly kept. Progress photos stored on your device and lined up over time, so the comparison is the same pose and the same light rather than whatever you can find in your camera roll.
• Achievements worth having. Milestones tied to real behaviour, like a hundred days logged being called a genuine lifestyle change, rather than a badge for opening the app three times.
• Weight as a trend, not a number. Daily weight is mostly noise. Kriterion shows the direction underneath it, with body fat and FFMI tracked alongside.

It shows its working.

A library written to be read, not cited. Searchable, filtered by Biological, Clinical and Metabolism, and short enough to actually finish. This is where "trust us" gets replaced with the reasoning.

• Where the app is deliberately conservative, it says so. Including when a more precise rule would imply a precision the studies do not support.
• Supplements get the same treatment. Structured doses that actually move your nutrient totals, with plain caveats about the evidence, including when the honest answer is "not much".
• Calculators that explain. Body fat, FFMI, one-rep max, genetic potential and adjusted body weight. Each one shows its working, not just its answer.