How to Calculate Your One Rep Max (1RM): Formulas & Chart
Your one rep max is the gold standard for measuring strength — but testing it directly is risky. Here's how to estimate it safely, plus how to use it to plan every workout.
If you lift weights — or want to start — you'll keep hearing one term: one rep max (or 1RM). It's the number that tells you how strong you really are, and it's the foundation of every serious training program.
The best part? You don't need to risk injury by attempting your absolute max. You can estimate it accurately from your regular workouts — and this guide will show you exactly how.
What Is a One Rep Max (1RM)?
Your one rep max is the maximum amount of weight you can lift for exactly one repetition of an exercise — with proper form, no cheating, and no help from a spotter.
It's the most common way to:
- Measure your absolute strength on exercises like the bench press, squat, and deadlift
- Program workouts (most programs prescribe weights as percentages of your 1RM)
- Track progress over weeks and months
Example: If your bench press 1RM is 80 kg, that means 80 kg is the heaviest weight you can press once with good form. You couldn't do 80.5 kg — not even for one rep.
The Formulas: Epley, Brzycki & More
Testing a true 1RM is stressful on your joints and nervous system. So researchers developed formulas that estimate your 1RM from a submaximal set — a weight you can lift for multiple reps (usually 2–10) before failure.
Here are the most popular ones:
Other Formulas (Quick Reference)
| Formula | Equation | Notes |
|---|---|---|
| Epley | Weight × (1 + Reps ÷ 30) | Most popular. Best for 1–10 reps. |
| Brzycki | Weight × 36 ÷ (37 − Reps) | Similar to Epley. Slightly lower estimates. |
| Lander | (100 × Weight) ÷ (101.3 − 2.67123 × Reps) | Less common. Similar results. |
| Lombardi | Weight × Reps0.10 | Good for very low rep ranges (1–5). |
Which one should you use? For practical purposes, Epley and Brzycki are the best. They give nearly identical results for sets of 3–6 reps, which is the sweet spot for accuracy.
Calculate Your 1RM Instantly 🏋️
Enter your weight and reps — get your estimated one rep max using multiple formulas, plus your training percentages.
Calculate My 1RM →Rep-Max Chart: Estimate at a Glance
If you don't want to do the math, this chart gives you a quick reference. It assumes you lifted to near failure:
| Reps Completed | % of 1RM | Example: 100 kg × 5 reps |
|---|---|---|
| 1 | 100% | 100 kg = your true 1RM |
| 2 | 95% | 105 kg estimated 1RM |
| 3 | 93% | 108 kg estimated 1RM |
| 4 | 90% | 111 kg estimated 1RM |
| 5 | 87% | 115 kg estimated 1RM |
| 6 | 85% | 118 kg estimated 1RM |
| 8 | 80% | 125 kg estimated 1RM |
| 10 | 75% | 133 kg estimated 1RM |
Note: Accuracy decreases as reps increase. For the most reliable estimate, use sets of 2–6 reps.
How to Use Your 1RM for Training
Once you know your 1RM, training becomes simple math. Most programs prescribe weights as a percentage of your 1RM, depending on your goal:
| Goal | % of 1RM | Reps per Set | Example (1RM = 100 kg) |
|---|---|---|---|
| Max Strength | 85–95% | 1–5 | 85–95 kg |
| Muscle Growth | 65–85% | 6–12 | 65–85 kg |
| Endurance | 50–65% | 12–20 | 50–65 kg |
Example: Your squat 1RM is 120 kg. For muscle growth, you'd train with 78–102 kg for 6–12 reps per set. Simple!
This is why tracking your 1RM matters — it turns random gym sessions into structured, progressive training. Combined with proper protein intake and macro balance, you've got everything you need to build strength efficiently.
Safety Tips for Testing Your 1RM
Estimating from submaximal sets is much safer than attempting a true 1RM. But if you do want to test it directly, follow these rules:
- Never test alone. Always have a spotter or use safety pins on a power rack.
- Warm up thoroughly. Start with 50% of your estimated 1RM for 5–8 reps, then 70% for 3–5 reps, then 85% for 1–2 reps.
- Rest 3–5 minutes between attempts. Your nervous system needs full recovery.
- Increase by small amounts. Add 2.5–5 kg per attempt, not 10 kg jumps.
- Stop at failure. If form breaks down or the bar slows significantly, that's your max. Don't force it.
- Beginners: skip true 1RM testing. Stick to estimation until you've lifted consistently for 6+ months.
How Often Should You Retest Your 1RM?
Retesting too often can interfere with your training and recovery. Here's a sensible schedule:
- Beginners (first 6–12 months): Every 6–8 weeks, or just estimate from your regular workouts
- Intermediate lifters: Every 4–6 weeks
- Advanced lifters: Every 8–12 weeks (or before a competition)
Pro tip: You don't need to test every exercise. Pick 2–3 main lifts (like squat, bench, deadlift) and track those. The rest will follow.
Frequently Asked Questions
Your one rep max (1RM) is the maximum amount of weight you can lift for exactly one repetition of an exercise with proper form. It is the standard measure of strength used to program workouts and track progress.
Use a submaximal set: lift a weight you can do for 2-10 reps to near failure, then apply a formula. The most common is the Epley formula: 1RM = weight × (1 + reps ÷ 30). For example, 100 kg for 5 reps gives an estimated 1RM of about 116.7 kg.
The Epley and Brzycki formulas are the most widely used and give similar results for rep ranges of 2-10. Epley (weight × (1 + reps/30)) is slightly more common. Accuracy drops beyond 10 reps, so use sets of 3-6 reps for the best estimate.
Testing a true 1RM carries higher injury risk, especially for beginners. Estimating from a 3-5 rep set is safer and accurate enough for most people. If you do test, warm up thoroughly, use a spotter or safety pins, and never attempt a 1RM alone.
Training programs use percentages of your 1RM. For strength, lift 85-95% for 1-5 reps. For muscle growth (hypertrophy), use 65-85% for 6-12 reps. For endurance, use 50-65% for 12-20 reps. Adjust as your 1RM improves over time.
Retest every 4-8 weeks, or whenever your training weights start feeling noticeably easier. Frequent 1RM testing can interfere with training and recovery, so estimated 1RM from your regular workouts is often the better approach.