Fitness that fits real life.
KAI Fitness brings gym training and timed HIIT together in one calm, focused app. Ten minutes or a full hour, at home, at the gym or outdoors: log every set, let the intervals run themselves, and keep a routine that survives a busy week.
Gym and HIIT, in one app
The same app covers the barbell and the stopwatch. You choose which one the day calls for.
Gym — strength and mass
Build your own routine, choosing exercises, sets, reps and rest, or start from a ready-made one. Log each set as you go: the app keeps the count, runs the rest timer and shows what you lifted last time before you start.
HIIT — timed circuits
Work and rest intervals run on their own, with cues you can follow without watching the screen. Pick a ready-made circuit across cardio, strength, endurance or low-impact work, or design your own round by round.
Seven screens, in order
What the app actually looks like while you use it.
The numbers, worked out while you train
In a gym session the maths happens in the app, not on your phone’s calculator.
Estimated 1RM
Enter weight and reps from any set and KAI estimates your one-rep max, without interrupting the session.
Warm-up ramps
Ready-made warm-up sets, calculated on the working weight you are about to lift.
Effort into load
RPE and RIR translated into a percentage of your 1RM, so “hard” turns into an actual number.
Full exercise catalogue
Every exercise comes with an animated demonstration of the movement, available from the first session.
History that stays
Calendar, past sessions and progress per exercise, so you can see what changed over the weeks.
No account
Nothing to sign up for. Your workouts are saved on your iPhone and are not sent to us.
What costs money, and what doesn’t
Gym and timed workouts, the full exercise catalogue and your history are free, from the first launch and with no account.
- Unlimited custom workouts — the free version keeps three gym routines and three timed ones
- All training techniques and advanced set types
- The complete session history for every exercise
- Advanced planning and the advanced tools inside gym sessions
PRO is a subscription, monthly, quarterly or yearly, purchased and managed through your Apple ID. Prices are shown in the app and there is no free trial. The details are in the terms and conditions.
Terms and privacy
The conditions of use and the handling of personal data for this app.
Before you start
KAI Fitness is a training tool, not a medical device, and it does not give medical advice. If you have a health condition, an injury or you are returning after a long break, check with a doctor before starting a new programme. For questions or problems with the app, write to us.