How hard you train
One rep max (1RM)
Updated 6 August 2026
Your one rep max, or 1RM, is the heaviest weight you could lift once with good form. It is the standard reference point for how strong you are on a given lift.
Almost nobody should test it. It is usually estimated from a set you already did, which is where the term e1RM, or estimated one rep max, comes from.
Why estimate instead of test
A genuine max attempt is fatiguing, needs a spotter, needs the technique to hold up under a load you have never handled, and can only be done occasionally without wrecking your training.
An estimate costs nothing. If you lifted 80kg for 6 reps, formulas such as Epley and Brzycki turn that into a maximum of roughly 93kg, and the estimate is accurate enough for programming as long as the set was within about ten reps of failure.
What it is actually for
A one rep max is a common yardstick. It lets you compare your bench today to your bench last year, prescribe training loads as percentages, and see where you sit against general strength standards.
It is most useful on big barbell lifts. On a lateral raise or a cable fly the number is close to meaningless, because those lifts are never trained anywhere near a single heavy rep.
The honest limits
Estimates drift as the rep count climbs. A set of 3 gives a good estimate, a set of 20 gives a rough one, because high rep sets are limited as much by endurance as by strength.
Your true maximum also moves daily with sleep, stress and food, sometimes considerably. This is why effort based targets such as reps in reserve often beat percentage based ones in a real training week.
In your plan
How Ionik Coach uses 1RM
Ionik Coach does not ask you to test a maximum, and it does not prescribe your training as percentages of one. Loads come from what you actually logged on that exercise, adjusted by how the sets felt.
If you tell the app a working weight during setup, it uses that as evidence about your general strength level rather than as a number for one lift. Those anchors can only ever make your starting loads lighter, never heavier, because the cost of starting too heavy on a first attempt is much higher than the cost of starting too light.
Work it out for yourself with the free one rep max calculator.
Common questions
Should I test my one rep max?
Most people never need to. Estimating it from a hard set of 3 to 8 reps is safer, cheaper, and accurate enough for every practical purpose.
Which one rep max formula is most accurate?
Epley and Brzycki are the two most common and agree closely in the 3 to 10 rep range. Beyond about 10 reps both drift, and Brzycki tends to read lower.
Why does my one rep max change day to day?
Because maximum strength is a snapshot of your current state, not a fixed property. Sleep, stress, food, and where you are in your training block all move it.
Related terms
- Rate of perceived exertion (RPE) A 1 to 10 rating of how hard a set felt. It is the same idea as reps in reserve, counted from the other end.
- Reps in reserve (RIR) How many more reps you could have done before failing. Two reps in reserve means you stopped two reps short.
- Progressive overload Gradually asking your body to do more than it is used to. It is the one rule every training plan is built on.
- Training age How long you have trained consistently, not how old you are. It is the single biggest input into how your plan is written.