| Formula | Est. 1RM ({{ unit }}) | Delta vs selected | Copy |
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| {{ row.label }} | {{ row.valueDisplay }} | {{ row.deltaDisplay }} |
| Step | Load |
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| {{ row.label }} | {{ row.loadDisplay }} |
| % of 1RM | Load ({{ unit }}) | Load @ TM | Typical reps | Use | Copy |
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| {{ row.pct }}% | {{ row.loadDisplay }} | {{ row.tmLoadDisplay }} | {{ row.repGuide }} | {{ row.focus }} |
| Reps | Max load ({{ unit }}) | % of 1RM | Typical use | Copy |
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| {{ row.reps }} | {{ row.loadDisplay }} | {{ row.intensityDisplay }} | {{ row.note }} |
One-repetition maximum, usually shortened to 1RM, is the heaviest load you can lift once with sound technique in a specific exercise. It matters because percentage-based training starts with that anchor. Once the anchor is plausible, sets, singles, and longer blocks can be loaded with much less guesswork.
A direct max test is not always the best first move. It asks for a true heavy single, reliable spotting or safeties, and enough freshness that fatigue does not hide your real strength. That is why coaches often estimate 1RM from a hard work set instead. A multi-rep set is easier to collect during normal training, but the answer is less certain than a tested max.
The uncertainty is not random noise. Rep-based formulas model fatigue in different ways, and those differences matter more as the set drifts away from a low-rep effort. A hard triple and a hard set of five often give a practical loading reference. A hard set of twelve can still help, but it is much easier to overread.
The real question, then, is not only what number comes out. It is whether the estimate is stable enough to guide your next training session, or whether it should stay a conservative planning aid until you gather a better set.
Rep-based 1RM prediction starts with two facts: the load that moved and the number of completed reps. Each equation then asks what single would be consistent with that set if fatigue followed the equation's own curve. Some formulas rise more steadily as reps increase. Others curve more sharply. That is why the same set can produce several plausible max estimates instead of one universal answer.
The relationship between repetitions and percentage of 1RM is also exercise-specific and person-specific. A squat, bench press, deadlift, and machine press do not all lose reps at the same rate, and a set taken close to failure behaves differently from a set stopped early. Showing the individual formulas first, then summarizing them with an average, median, floor, or ceiling, keeps that uncertainty visible instead of pretending that every equation tells the same story.
The raw estimate comes from the included equations. The selected 1RM is then used to derive training max, current set intensity, percentage loads, and the rep ladder.
| Symbol | Meaning here | Why it matters |
|---|---|---|
| w | The working weight from the completed set | This is the direct load that all formulas start from. |
| r | The number of completed reps in that set | Higher reps usually create more divergence between formulas. |
| Ei | One formula-specific 1RM estimate | Keeping them visible helps you judge disagreement instead of hiding it. |
| TM | Training max, set as a percentage of the selected estimate | It provides a built-in buffer below the headline 1RM estimate. |
| Formula | Equation used here | Interpretation note |
|---|---|---|
| Epley | 1RM = w x (1 + r / 30) |
A familiar linear rule that rises steadily with each added rep. |
| Brzycki | 1RM = (w x 36) / (37 - r) |
Often used in strength-testing discussions and can drift more at higher reps. |
| Lombardi | 1RM = w x r^0.10 |
A curved model that usually behaves differently from the linear family. |
| Mayhew | 1RM = (100 x w) / (52.2 + 41.9 x e^(-0.055 x r)) |
A curvilinear estimate commonly discussed in bench-based research. |
| O'Conner | 1RM = w x (1 + 0.025 x r) |
A simple rule that usually lands on the conservative side of the group. |
| Wathan | 1RM = (100 x w) / (48.8 + 53.8 x e^(-0.075 x r)) |
Another curved model that helps show how much the estimate changes by method. |
| Lander | 1RM = (100 x w) / (101.3 - 2.67123 x r) |
Useful as another linear comparison point inside the formula band. |
A true single is handled differently. When the rep count is one, the entered load becomes the estimate directly. For multi-rep sets, the selected formula family can also be inverted to build projected 2RM through 12RM loads. The training max then feeds the warm-up ladder and the percentage load table. Plate rounding happens after the raw calculations, so exact mode preserves decimals while the other presets snap loads to the plates you actually have.
| Rule group | Boundary used here | What it is saying |
|---|---|---|
| High confidence | reps <= 5 and spread <= 4% |
Low reps and tight agreement make the estimate stronger for programming. |
| Moderate confidence | reps <= 8 and spread <= 8% |
The number is still useful, but it should not be confused with a tested max. |
| Caution | Anything looser than the two rules above | The estimate is better read as a planning anchor than as a max claim. |
| Technique / speed | 0% to under 60% of 1RM |
Labeled for fast, low-stress loading. |
| Volume | 60% to under 70% |
Labeled for repeatable workload and longer sets. |
| Base strength | 70% to under 80% |
Labeled as the main middle range for many strength plans. |
| Heavy strength | 80% to under 87% |
Labeled for lower-fatigue heavy work. |
| Peak practice | 87% to under 94% |
Labeled for near-top singles, doubles, and triples. |
| Max test | 94% and above |
Labeled as testing territory rather than routine volume. |
Those confidence and intensity labels are built-in planning rules, not universal standards. They are there to slow down overconfident reading and to turn the estimate into a more usable loading map.
For a first pass, use one recent work set from the exact lift you want to program, leave all seven formulas enabled, and keep the default consensus average. That gives you the broadest view of formula agreement before you start narrowing the estimate. If you have both a hard triple and a hard set of eight from the same lift, start with the triple.
Next, make the load outputs match your gym. Switch the unit, choose an exact or plate preset, and set the rounding mode. The page is much more useful once the training table and rep ladder are snapped to the jumps you can really load on the bar.
The most common misread is to treat a neat-looking estimate as proof of a true max. The confidence badge is there to prevent that. If the page shows Caution, if reps climb above about 10, or if the formulas split widely, take the result as a conservative planning number, not a claim about what you must be able to lift for one clean rep today.
A sensible next step is simple: set the training max only after you have read the estimate, the formula span, and the confidence label together. If those three pieces do not agree, lower the training max or gather a lower-rep set before planning heavier work.
Use one completed set and move from estimate to loading in a steady order.
The top-line estimate is only the first part of the answer. The low-to-high formula span shows how much room sits around it, and the confidence label tells you how much trust that span deserves. The safest reading is to treat all three as one package.
| Output | What it means | Common overread |
|---|---|---|
| Selected estimate | The planning anchor picked from the active formulas and summary rule | Reading it as a proven max-day single |
| Formula span | The low and high edges of the included formulas | Ignoring a wide band and programming too aggressively |
| Confidence label | A quick read based on rep count and formula spread | Assuming a large estimate is trustworthy just because it looks impressive |
| Current set intensity | How heavy the source set was relative to the selected estimate | Forgetting that a set far from failure can make intensity look deceptively low |
| Training max | A buffered loading anchor below the selected estimate | Treating it as weaker-than-real instead of appropriately conservative |
| Rep max ladder | Projected 1RM to 12RM loads from the same selected estimate | Taking every projected rep target as guaranteed on the day |
The quick cards on the training tab deserve separate attention. The heavy triple anchor sits at about 82% of training max, and the volume five anchor sits at about 72% of training max. Those are useful loading landmarks when the estimate looks stable. They are not promises that every lifter will always get exactly three reps or five reps at those loads.
If the current set intensity looks strange, check the source set before you blame the math. A five-rep set that reads unusually light may have been well short of failure. A high reading may mean the set was close to a real rep max, the formula choice is conservative, or the lift loses reps quickly as weight climbs.
A set of 100 kg for 5 reps produces a selected estimate of about 115.49 kg when all seven formulas are included and the summary rule stays on consensus average. The formula span runs from 112.50 kg to 119.01 kg, which is a spread of about 5.6%. That lands in the page's Moderate confidence range. With the default 90% training max, the working anchor becomes about 103.94 kg. The projected 3RM from the same estimate is about 105.71 kg.
A set of 80 kg for 12 reps produces a selected estimate near 110.12 kg, which can look surprisingly strong at first glance. The problem is the spread. The formulas run from about 102.57 kg to 115.53 kg, a split of roughly 11.8%, so the page correctly drops the label to Caution. That is the moment to slow down. The corrective path is to keep the result for rough volume planning, lower the training max, or collect a harder lower-rep set before you plan singles or very heavy triples from it.
A set of 225 lb for 3 reps gives a raw consensus estimate near 245.94 lb. With 5 lb rounding active, that reads as about 245 lb, the formula band rounds to roughly 240 lb to 255 lb, and the 90% training max rounds to 220 lb. The rounded rep ladder then gives a projected 3RM near 225 lb and a projected 5RM near 215 lb. This is a good example of why plate rounding matters: exact decimals may be more precise on paper, but rounded loads are often more useful once you are actually loading the bar.
Changing a 1RM estimate changes the loads you may put on a bar, so caution matters. This page is a programming aid, not medical clearance, injury assessment, or a substitute for coaching during a true max attempt.
If you are new to lifting, returning from injury, dealing with pain, or rebuilding after a long layoff, keep the estimate conservative and follow the advice of a qualified coach or clinician. Use spotters, safeties, or both for heavy work, and stop if technique breaks down before the target reps are complete.
No. A tested 1RM is the heaviest successful single under real lifting conditions. This page estimates that number from a completed set and shows how much the formulas agree or disagree.
Because they model fatigue differently. Some are more linear, some are more curved, and lifts do not all lose reps at the same rate. The disagreement is useful information because it tells you how sensitive the estimate is to the chosen model.
The page switches to Caution when the source set uses more than 8 reps, when the formula spread is wider than 8%, or both. The practical fix is not to chase the bigger number. Use a lower training max, switch to the conservative floor, or retest with a harder lower-rep set.
Average is the balanced default. Median is useful when one formula looks like an outlier. Floor is the safer option when you want conservative loading. Ceiling is the least forgiving choice and makes the most sense only when you already trust the source set and want an aggressive planning anchor.
The entered weight becomes the estimate directly. Multi-rep prediction equations are only used when the set has more than one rep.
The calculations, charts, and exports are generated in the browser. The page also mirrors the current settings into the URL query string, so a saved or shared link can reveal the weight, reps, formula choices, and related settings used in that run.