---
type: WebApplication
title: "One Rep Max Calculator: Epley and Brzycki"
description: "Estimate your one-rep max from any set with the Epley or Brzycki formula, see a percentage table, and get the plates to load per side."
resource: https://quietgains.app/tools/one-rep-max-calculator
tags: ["1rm", "one rep max", "epley", "brzycki", "plates"]
timestamp: 2026-09-22
---

# What is my max, and which plates?

A one-rep max (1RM) is the heaviest weight you can lift for one repetition; a 1RM calculator estimates it from a heavier set of several reps. One set in. An estimated max out, with a percentage table and the discs for each side.

## How the answer adds up.

One formula, applied to the set you did.

1. The set: 100 kg (100 kg for 6 reps)
2. The formula: 1.2 × (100 × (1 + 6 ÷ 30))
3. Your max: 120 kg (rounded to the nearest 2.5 kg)

| Percent | Kilograms | Reps by Epley |
| --- | --- | --- |
| 95% | 115 | about 1.6 reps |
| 90% | 107.5 | about 3.3 reps |
| 85% | 102.5 | about 5.3 reps |
| 80% | 95 | about 7.5 reps |
| 75% | 90 | about 10.0 reps |
| 70% | 85 | about 12.9 reps |

Plates per side at 85%: 25 + 15 + 1.25 on a 20 kg bar, 102.5 kg in total.

## Formula and sources

Epley: 1RM = weight × (1 + reps ÷ 30). A single returns the weight itself, as the QuietGains app records it [1].

Brzycki: 1RM = weight × 36 ÷ (37 − reps) [2].

Reps run from 1 to 12, the range the app estimates from. The estimate rounds to the nearest 2.5 kg, and so does each row of the table.

Reps beside each percentage: Epley 30 × (100 ÷ percent − 1); Brzycki 37 − 36 × percent ÷ 100.

Plates: a 20 kg bar with discs of 25, 20, 15, 10, 5, 2.5 and 1.25 kg, heaviest first on each side and rounded down when the target cannot be made exactly, the method the app’s plate calculator uses.

1. Epley B. Poundage Chart. Boyd Epley Workout. Lincoln, NE: Body Enterprises; 1985.
2. Brzycki M. "Strength testing: predicting a one-rep max from reps-to-fatigue." J Phys Educ Recreat Dance 1993;64(1):88-90. doi:10.1080/07303084.1993.10606684

## Reading the result

### Where the formulas meet

For a single, both return the weight itself, and they agree again at ten reps. From two to nine reps Epley reads higher; above ten, Brzycki does.

### Percentages of the estimate

The table shows common percentages of the estimate, rounded to 2.5 kg, beside the reps the chosen formula links to each one.

### Plates assume a 20 kg bar

And 25, 20, 15, 10, 5, 2.5 and 1.25 kg discs. Anything it cannot make exactly, it rounds down.

## Related

- [Macros](https://quietgains.app/tools/macro-calculator)
- [Body composition](https://quietgains.app/tools/ffmi-calculator)
- [Progressive overload](https://quietgains.app/journal/progressive-overload)
- [Rest between sets](https://quietgains.app/journal/rest-between-sets)

Your log already knows your max. QuietGains tracks your estimated max from every set you log. Arithmetic only. Not medical advice.