iPhone and Apple Watch

Knurl

Lift the bar, not a calculator.

Knurl runs a four-week barbell programme for one lifter. Tell it what you can manage for five reps and which plates your gym actually owns. It works out the rest: what goes on the bar, which plates to slide on, when to stop resting, and how much the weight goes up when the cycle rolls over.

Up next

100kg

15 25 25 15

Per side 25 + 15 kg

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On the App Store shortly.

What it does

Starts without your numbers Enter a weight you could manage for five reps, or take the light default. The first session of each lift asks how it felt and moves the weight from there.
Does your gym's plate maths Tell it the bar and the pairs of plates you can reach. It never asks for a weight you cannot load, and when it cannot hit the target it shows the nearest bar and says what was asked for.
Times every rest The clock starts when you tick a set off, and it finishes on the Lock Screen and the Dynamic Island whether or not the app is open.
Puts the sets on your wrist Mark a set done from an Apple Watch without picking the phone up off the floor.
Only raises what you earned Miss the reps on a top set and that lift holds its weight at the cycle roll. Miss them twice running and it steps back. The bar never climbs past what you can lift.
Writes to Apple Health Finished sessions land as strength training workouts, with charts in the app for training max, estimated one rep max and weekly volume.

The four weeks

Three working sets a day, four lifts a week, in whatever order you like. The percentages are of your training max, which is ninety per cent of what the app reckons you could lift once.

Week	Working sets	Reps
One	65 / 75 / 85%	5, 5, 5+
Two	70 / 80 / 90%	3, 3, 3+
Three	75 / 85 / 95%	5, 3, 1+
Four	40 / 50 / 60%	5, 5, 5 · deload

The + is the set that decides everything: take as many reps as you have in you, and the app reads your next cycle off what you got.

On the phone

The Knurl home screen, showing overhead press at 55 kg up next with a loaded bar drawing, a start button, and the week's other three lifts below it. — The week is one card and four rows. One button starts the lift you picked.

A warm-up set in Knurl: 25 kg for five reps, with a bar drawing showing a 2.5 kg plate each side and a Done button. — Every set says the weight, the reps, and which plates go on each side.

Knurl resting between sets, a countdown reading 56 seconds above the next set of 32.5 kg for five reps. — Rest counts itself down, then tells you what is next and what to load.

Privacy

Knurl collects nothing.

There is no account and no sign-in. The app contains no network code at all, no analytics, no advertising, no tracking and no third-party code, so there is no server for your training to go to and nobody here can see it. What Knurl knows about you is a file on your phone, and it goes wherever your own device backup goes.

Two things reach outside the app, both with your permission, both on your own device:

Apple Health. If you allow it, a finished session is written as a strength training workout, and your body weight is read back so the app can work out what bodyweight assistance sets are costing you. That is Apple's store on your device, not ours, and you can switch either direction off in iOS Settings.
Notifications. Rest timers, and one reminder on the day you usually train, are scheduled by the app on the phone itself. Nothing is sent from anywhere.

Deleting the app deletes everything it holds.

Last updated 21 September 2026

Support

Something broken, a number that looks wrong, a gym whose plates it cannot cope with? Write to craig@barkingiguana.com. It reaches the person who wrote the app, and that person answers.