Epley Formula Calculator

Reviewed by Dr. Damir Vučić, PhD, Physical & Health Education (FOI) • Last updated 2026-07-01

The Epley Formula Calculator estimates your one-rep max from weight and reps and suggests percentage-based training loads.

Epley Formula Calculator Estimate your one-rep max (1RM) using the Epley formula from a lifted weight and completed reps. This is a fitness estimate, not medical advice; results vary by technique, fatigue, and training history.

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About the Epley Formula Calculator

This tool predicts your one-repetition maximum, or 1RM, from the weight you lifted and the reps you performed. It uses the Epley equation, a simple linear model that fits typical strength curves at low to moderate rep ranges. The goal is to get a solid estimate of your top strength without the risk of testing a true max.

Coaches and lifters use 1RM estimates to plan intensity zones, choose working weights, and set progression targets. You can translate an estimate into loads for strength, hypertrophy, or power sessions. The calculator also helps you compare sessions over time using consistent metrics.

You only provide three things: the lift, the weight used, and the reps done in one set. The calculator returns a predicted 1RM and common training percentages. You can then align those values with your program’s targets and adjust for day-to-day readiness.

Epley Formula Formulas & Derivations

The Epley method is based on a straightforward relationship between weight and reps. It assumes each extra rep represents a roughly equal drop in the percentage of your 1RM. Here are the common forms you will use.

Primary equation for predicting one-rep max: 1RM = weight × (1 + reps ÷ 30).
Solve for weight at a given repetition count: weight at reps N = 1RM ÷ (1 + N ÷ 30).
Solve for approximate reps at a given weight: reps ≈ 30 × (1RM ÷ weight − 1).
Link to intensity: percent 1RM at reps N ≈ 1 ÷ (1 + N ÷ 30). For example, 5 reps ≈ 1 ÷ (1 + 5/30) = about 85% 1RM.
Comparing to other models: Brzycki uses 1RM = weight × 36 ÷ (37 − reps), which tracks closely at 1–10 reps. Differences grow at higher reps.

These relationships come from fitting a simple linear model to observed performance. They hold best for compound lifts and rep ranges where fatigue per rep is relatively consistent. Past about 10–12 reps, assumptions break down and prediction error grows.

How the Epley Formula Method Works

The method maps a submax effort to your top potential by modeling how reps reduce the percentage of your max. You do a hard set within a reliable rep range. Then the formula scales the load back up to estimate the maximum single.

Choose a weight you can lift for 3–10 reps with solid form.
Perform one controlled set near failure, keeping technique consistent.
Record the exact weight and the completed rep count.
Apply the formula to estimate 1RM and derive percent 1RM for training intensity.
Use those outputs to set loads for your session’s targets and long-term metrics.

This approach reduces risk compared to true max attempts. It allows frequent check-ins so you can track trends and adjust targets for each training phase.

What You Need to Use the Epley Formula Calculator

Gather a few details before you start. You only need one quality set to near failure and accurate recording. The calculator then converts those inputs into a 1RM estimate and useful training percentages.

Exercise name (e.g., back squat, bench press, deadlift).
Load lifted (barbell plus plates, or dumbbells) with unit selection.
Reps performed in the set, completed with consistent form.
Unit setting for weight, such as kilograms or pounds.
Optional context like RPE or reps in reserve, used to gauge effort.

The formula is most reliable between about 1 and 10 reps. Very high reps, grinders, long pauses, or clusters can skew results. Mixed tempo or form breakdown can also inflate estimates, so keep technique tight during the test set.

How to Use the Epley Formula Calculator (Steps)

Here’s a concise overview before we dive into the key points:

Select your exercise to keep results comparable across sessions.
Warm up, then choose a test weight you expect for 3–10 clean reps.
Perform one hard set near failure while keeping consistent tempo and range of motion.
Enter the exact weight used and the number of completed reps.
Confirm the unit (kilograms or pounds) and review the predicted 1RM.
Use the suggested percent 1RM loads to set today’s intensity targets.

These points provide quick orientation—use them alongside the full explanations in this page.

Worked Examples

Example 1: A lifter performs the back squat with 100 kilograms for 5 reps. Using the equation, 1RM = 100 × (1 + 5/30) = 100 × 1.1667 = 116.7 kilograms. If the session calls for 5 sets of 3 at 85% 1RM, the target load is roughly 0.85 × 116.7 ≈ 99.2 kilograms, so 100 kilograms is a practical choice. What this means: The lifter can set today’s intensity at about 100 kilograms to align with strength targets.

Example 2: A lifter bench presses 185 pounds for 8 reps. The estimate is 1RM = 185 × (1 + 8/30) = 185 × 1.2667 ≈ 234.3 pounds. For a hypertrophy block at 70% 1RM, the working sets would be around 0.70 × 234.3 ≈ 164 pounds. What this means: The lifter can program sets around 165 pounds to hit the planned volume and intensity metrics.

Accuracy & Limitations

The Epley approach is dependable for many compound lifts in moderate rep ranges. Still, it is a model with assumptions, and real performance varies across exercises and athletes. Consider these points when using the estimates.

Prediction error is typically small at 1–10 reps, and larger beyond 12 reps.
Different lifts have different fatigue profiles, which can shift accuracy.
Form drift, long pauses, or grinding reps can inflate the estimate.
Narrow grip or unusual tempos change the stimulus and the prediction.
Novices may improve quickly, so repeat checks can outdate older estimates.

Treat the output as a helpful guide, not a strict rule. Use your training log, bar speed, RPE, and recovery to fine-tune. Adjust loads when readiness is low, and increase targets when trends and performance improve.

Disclaimer: This tool is for educational estimates. Consider professional advice for decisions.

Units Reference

Units make your results consistent and comparable. A small mismatch between kilograms and pounds can throw off intensity targets and progress metrics. Use the same unit each time, and confirm it before saving or sharing results.

Common quantities and symbols for Epley-based strength calculations
Quantity	Symbol	Typical Unit	Notes
Load lifted	W	kg or lb	Include barbell weight when applicable.
One-repetition maximum	1RM	kg or lb	Predicted by the Epley equation.
Intensity	%1RM	percent	Used to set training targets.
Repetitions	reps	count	Completed reps with standard form.
Rating of Perceived Exertion	RPE	1–10 scale	Higher values mean higher effort and intensity.
Reps in Reserve	RIR	count	Estimated reps left at the end of the set.

Read the table by matching the quantity you track to its symbol and unit. Keep the same units across sessions so percent 1RM and progression remain accurate. When converting, 1 kilogram is about 2.2046 pounds.

Common Issues & Fixes

A few pitfalls can throw off your estimate or make targets too aggressive. These issues are easy to fix with simple habits.

Problem: Rushed warm-up. Fix: Use 2–3 build-up sets before your test set.
Problem: Inconsistent range of motion. Fix: Standardize depth and bar path every session.
Problem: Very high reps. Fix: Test within 3–10 reps for better accuracy.
Problem: Unit mix-ups. Fix: Confirm kilograms or pounds in the Calculator before saving.
Problem: Technique breakdown. Fix: Stop the set if form slips to avoid inflated numbers.

Note your RPE or RIR to add context to each estimate. Over time, you will see trends and can adjust intensity up or down to stay aligned with your weekly targets.

FAQ about Epley Formula Calculator

How accurate is the Epley estimate compared with a true max?

At 3–10 reps with good form, the estimate is often within a small margin of a tested max. After 12 reps, accuracy declines. Treat the result as a guide for setting loads, not a guarantee of a single-attempt outcome.

Which rep range should I use for the best prediction?

Most lifters get dependable results from sets of 3 to 10. Sets of 5 to 8 are a practical sweet spot. They balance safety, stable technique, and usable accuracy for planning intensity.

Can I use the equation for bodyweight exercises like pull-ups?

Yes, but include total load. For pull-ups, total load is your bodyweight plus any added weight. Record reps and total weight to estimate an effective 1RM and set training targets.

How does Epley compare to Brzycki or other formulas?

Epley and Brzycki give very similar results at low to moderate reps. Differences grow as reps increase. Pick one method and use it consistently so your progress metrics remain comparable over time.

Glossary for Epley Formula

One-Repetition Maximum (1RM)

The heaviest load you can lift once with standard technique for a given exercise.

Intensity

The relative load used for training, often expressed as a percentage of your 1RM.

Repetition (Rep)

One complete movement of an exercise through the chosen range of motion.

Rating of Perceived Exertion (RPE)

A 1–10 scale describing effort. Higher numbers mean harder sets and fewer reps left.

Reps in Reserve (RIR)

An estimate of how many reps you could still perform at the end of a set.

Progression

A planned increase in training stress over time using load, reps, or sets.

Training Targets

Specific intensity, volume, or performance goals you aim to hit in a session or cycle.

References