1RM Calculator (kg)
Estimate your one rep max (1RM) in kilograms from a submaximal set. Enter the weight you lifted and how many reps you completed with good form.
What is a one rep max?
Your one rep max (1RM) is the maximum weight you can lift for exactly one repetition with proper technique. It is commonly used in strength training to set working weights for exercises such as the squat, bench press, deadlift, overhead press, and rows.
A direct max test can be demanding, so lifters often estimate 1RM from a set of multiple reps. That is exactly what this one rep max calculator kg does.
How to use this 1RM calculator in kilograms
- Enter the load you lifted in kg.
- Enter the number of reps completed with solid form.
- Select your preferred formula (or use Average for a balanced estimate).
- Click Calculate 1RM to see your estimated max and training loads.
For best accuracy, use a hard set between 2 and 10 reps, ideally stopped close to technical failure.
Formulas used in the calculator
Epley formula
Popular and practical for general strength training. It tends to work well in moderate rep ranges.
Brzycki formula
Another widely used equation, often preferred in classic strength settings and coaching calculators.
Lombardi formula
Uses an exponent model and can produce slightly different estimates at higher reps.
Mayhew and O'Conner formulas
These formulas provide additional estimates and help balance differences across rep ranges. Choosing “Average” can reduce overreliance on a single equation.
How to apply your estimated 1RM
Once you know your estimated 1RM, you can build sessions by percentage:
- 90–95%: heavy singles/doubles, peak strength work.
- 80–89%: classic strength sets (3–6 reps).
- 70–79%: volume and technique development.
- 60–69%: speed work, warm-up sets, and recovery-focused sessions.
Many programs also use a training max (e.g., 90% of estimated 1RM) for conservative progression.
Example (kg)
If you bench press 80 kg for 5 reps, your estimated one rep max is typically around the low-to-mid 90 kg range, depending on formula. From there, 80% work would be around mid-70 kg, and 70% work around mid-60 kg.
Accuracy and safety notes
- All 1RM calculators are estimates, not guarantees.
- Accuracy decreases as reps get very high (especially above 10–12).
- Exercise selection matters: compound barbell lifts are usually more predictable than isolation lifts.
- Always prioritize form and appropriate spotting/safety equipment.
FAQ
Is this calculator only for kilograms?
Yes. This page is designed specifically for kg input and kg output.
Can beginners use a 1RM calculator?
Absolutely. Beginners often benefit from estimated 1RM methods because they avoid unnecessary maximal attempts while still enabling structured progression.
Should I retest often?
A practical approach is recalculating every 4 to 8 weeks from your best recent working sets, then adjusting training loads gradually.