A workout tracker that tells you
your next move, and why.
A notebook or an app will keep your records. But what weight to lift next is still yours to work out. DELT began with a plateau: training from a handwritten notebook, and realizing the records never said what came next.
From the rep range you choose and your last session, DELT calculates your next weight and reps, and shows you the reason alongside them.
Crop of ALast time, today’s target, and the reason, openedDouble progression, where the weight goes up once every set reaches the top of your rep range, runs on your records without cutting corners. Whether to add weight, and what happens after a miss, are both calculated from your records and the rules. No AI estimates, and no calculations you can’t see into.
You choose the rep range for each exercise. Research shows muscle growth happens across a wide 5–30 rep range, and which range fits depends on your goal, preference, and equipment.
One rep is added to your lowest set from last time.
Same weight until every set reaches the top of the range.
From here, add one rep at a time again.
Not your top set: one rep is added to the set with the fewest reps. The weight stays put until every set reaches the top of the range.
Barbells go up by two of your lightest plates, machines to the next step on the stack, and dumbbells by their increment. You can set all of these to match your gym’s equipment. DELT never suggests a weight you can’t load.
Miss once and you try the same weight again. Only when you miss twice in a row at the same weight does it drop 5%. A session ended with planned working sets left undone doesn’t count as progress.
Records from a different rep range (heavy and volume days) and records on different registered equipment aren’t mixed. Stalls are judged against how often you usually progress.
You can also record RIR (reps in reserve), and last time’s value appears right above today’s row. It isn’t used in the suggestion, because there is no well-supported table for turning RIR into a weight.
One study found that adding reps and adding weight built muscle about equally (Plotkin et al., 2022). Double progression alternates between the two.
Read: Double Progression →
Today’s weight and reps appear right under your last session. A one-line reason tells you why those numbers. If you disagree, you can type over them.
The weight and reps are already there, so when the set is done, you just tap ✓. That keeps the only thing on your mind mid-workout to the next set. The rest timer starts the moment you tap.
Your rest time shows at the bottom of the screen. Switch to another app or lock your iPhone, and the time left stays on the Lock Screen and in the Dynamic Island.
DELT counts the sets each muscle group got over the last 7 days and lines them up against the ranges shown in research. Without adding anything up yourself, you can see which muscles are under the range and which are over.
Crop of AOne pair of last-time and today rowsLast time’s numbers sit right above today’s row, so comparing them is just a glance up and down.
Crop of EThe weight keypad and the plate lineEnter a weight, and DELT shows which plates to load on each side of the bar, and how many.
Crop of FRows with a single white-framed ✓So what comes next is clear at a glance.
Crop of shot GThe “Keep the screen on during workouts” setting and its noteTurn it on in Settings, and your iPhone won’t sleep while the workout screen is open. No unlocking between sets.
During a workout, the next set should be all you need to look at. So DELT keeps everything else off the screen.
The screens are built from shades of white and gray, so color doesn’t steer your mood and the numbers read as they are.
No streak counters, no countdowns, no “limited time” offers. Whether you keep going is your decision.
Go past a guideline and you won’t get a red warning. DELT shows how far past it, as a number.
There are no ads on the screen, so nothing unrelated to training cuts into the set you’re on.
Your workouts, body weight, and meals are all stored on your iPhone. DELT has no server that receives your records, so DELT never sees or holds them. There’s no account and no email address to give, and the app doesn’t track you.
Your records are backed up automatically every day. If iCloud Drive is on, the backup is also kept in your own iCloud Drive, so opening DELT on a new iPhone brings everything back from there.
You can also import records from other apps that export CSV, so your history doesn’t have to stay behind.
DELT is free until you’ve recorded 20 sessions or 30 days have passed since you started, whichever comes later.
No subscription, and nothing more to buy. The price is the one shown on the App Store.
Logging meals and body weight, and exporting your records, stay available even if you don’t buy.
DELT is a tool for learning to judge from your own records and the evidence. The methods and research behind its suggestions are in the Library, with sources.
All Library articles →DELT counts progress in just two ways: lifting a heavier weight than last time, and doing more reps than last time at a weight you’ve lifted before. It doesn’t count calculated numbers like an estimated 1RM. What you see is your records adding up on those two, as they are.
Features and screens may change before release.
