Estimate the load you could lift for one clean rep

The estimate exists because a true max is expensive in neural fatigue and joint risk. Competitive lifters save it for peaks. The rest of the year, programming uses percentages of a training 1RM, refreshed from heavy sets. An 80 kg (176 lb) set of 8 with 3 to 4 RIR describes a different 1RM than the same load at 0 or 1 RIR. Stay in the 2-to-8-rep range. Error grows past 10 reps. At 1 rep all three formulas return the load itself.

The calculator does not diagnose relative strength and does not compare people. A 100 kg (220 lb) bench from a 70 kg lifter and from a 110 kg lifter are not the same fact. Read the number only for the movement, range, and equipment of the input set.

Worked example: 80 kg for 8 reps. Epley: 80 × (1 + 8 / 30) = 80 × 1.2667 = 101.3 kg. Brzycki: 80 × 36 / (37 − 8) = 2,880 / 29 = 99.3 kg. Lombardi: 80 × 8^0.1 ≈ 80 × 1.2311 = 98.5 kg. The mean is (101.3 + 99.3 + 98.5) / 3 = 99.7 kg (about 220 lb).

Second example, 100 kg for 5: Epley 100 × (1 + 5 / 30) = 116.7 kg; Brzycki 100 × 36 / 32 = 112.5 kg; Lombardi 100 × 5^0.1 ≈ 117.5 kg; mean 115.6 kg. At 10 reps Epley and Brzycki meet at w × 4 / 3; Lombardi sits lower. Past 10, Brzycki inflates as the 37 − r denominator shrinks. FITTA calculates with these coefficients and rounds to one decimal place.

The chart is a training convention, not a physiological law. Lifters with more slow-twitch fiber or more endurance work often squeeze extra reps at the same percentage. Lifters who are strong at a max and undertrained at volume fail sooner. Use the table to build the week, not to predict the exact failure point of that session.

If the 1RM came from an 8-rep set, 80 percent will land near the load you already used. Use the chart for the other rep targets and for weekly progression, not to circularly confirm the same set. The percentage belongs to the lift you tested. Do not carry 80 percent of your bench onto overhead press, or of your deadlift onto squat.

Read the 1RM only on the lift you tested, with the same range, pause, and equipment rules. Compare it with the last estimate of that same movement. A 2 to 3 percent rise over 4 to 6 weeks, with stable technique, is real progress. A 10 percent jump in seven days is almost always a closer-to-failure input set, or a previously easy training load, not a new physiological ceiling.

Outside a plausible band, recheck load, reps, and RIR. A 1RM below a triple you already hit, or 15 to 20 percent above recent history, points to a bad input. The calculator cannot see spotters, a hex bar, a mixed grip, or how hard a deficit day drained glycogen from the test set.

Mixing units is third: typing pounds into a kilogram field inflates 1RM by about 2.2 times. Counting a partial, a chest bounce, or a cut range invents a max that does not exist on the full lift. Recalculating every session from a warmup set pollutes the log. Applying the same percentage to every exercise ignores that reps available at 80 percent differ among squat, deadlift, and curl.

Treating the estimate as a meet max and attempting it the same day stacks test-set fatigue onto a true single. On an aggressive deficit or short sleep, the input set is already suppressed and the formula only echoes that bad day.

• Use a near-failure set of 2 to 8 reps
• Enter load in kilograms, not pounds
• Do not estimate from more than 10 reps
• Do not count partials or bounce reps
• Recalculate on the same lift and variation
• Do not attempt the estimated max on test day

In a deficit, training 1RM can fall even with stable technique. Do not chase the old number by cutting more calories. Take the input set on a day with reasonable glycogen, not at the end of a dry cut. Protein at 1.6 to 2.2 g per kg (about 0.7 to 1.0 g per lb) and enough sleep support the heavy set that feeds the formula. A 200 to 400 kcal surplus helps the max rise, but it does not replace progressive overload.

In the app, FITTA calculates 1RM with the same coefficients and ties the number to that day’s session, weekly volume, and what you eat and drink. This page is the starting point. The plan lives in the ongoing log of sets, meals, and recovery.