One-rep max: Epley, Brzycki and average
One-rep max estimates your single heaviest lift from reps: 100 kg × 5 reps is 116.7 kg Epley and 112.5 Brzycki, averaging 114.6 kg. Epley suits lower reps, Brzycki higher ones, and the average steadies both. This calculator is built for fast, private, offline use in your browser. Every formula runs locally and is verified against official sources. You enter the key numbers, see the result instantly and check the steps.
TL;DR
- Epley = weight×(1+reps÷30); Brzycki = weight×36÷(37−reps); the tool averages both and builds the rep table from the average.
- Formulas: Epley = w×(1+r÷30) | Brzycki = w×36÷(37−r)
- Example 1: 100 kg × 5 reps — Epley: 100×(1+5÷30) = 116.7 kg
How it works
Epley = weight×(1+reps÷30); Brzycki = weight×36÷(37−reps); the tool averages both and builds the rep table from the average. Start with clean data, keep the same units and follow the order in the formula. The tool does the arithmetic, you choose rate, period or factor. A second example with different numbers shows how the result scales.
The math
100 kg × 5: Epley 100×(1+5÷30)=116.7, Brzycki 100×36÷32=112.5, averaging 114.6 kg. Table from 114.6: 2×110.0, 3×105.4, 5×96.3, 8×90.5, 10×83.6, 12×76.8. Check 80 kg × 1: Epley 82.7, Brzycki 80.0, averaging 81.3 kg.
Average of both rules. Rep table scales down from the 1RM.
Examples
Example 1: 100 kg × 5 reps
- Epley: 100×(1+5÷30) = 116.7 kg
- Brzycki: 100×36÷32 = 112.5 kg
- Average 1RM: 114.6 kg
Example 2: 80 kg × 1 rep
- Epley: 80×(1+1÷30) = 82.7 kg
- Brzycki: 80×36÷36 = 80.0 kg
- Average: 81.3 kg
When to use it
✦ Powerlifting program
Set training percentages: 85% of 114.6 is about 97 kg for working sets.
✦ Plate math
Load the bar: round 114.6 to 115 kg of plates.
⚠ Common mistakes
- Testing instead of estimating: true 1RM attempts injure, estimate from 3-5 reps.
- Beyond 10 reps: both formulas drift, above 10 reps it is cardio.
- Mixing units: 100 kg is not 100 lb, keep one unit.
FAQ (6)
100 kg × 5 is what max?
114.6 kg average (116.7 Epley, 112.5 Brzycki).
Which formula?
Both averaged; Epley runs higher, Brzycki lower.
What happens to my weight, height or other health data?
It never leaves your phone. BMI, BMR, body-fat — all computed on-device, no upload, no account. That's intentional for health data: you can check a BMI of 22.8 or a TDEE of 2,100 kcal without worrying about a server log. Closing the tab clears the form from memory.
Does it work offline at the gym or on a plane?
Yep. Once the page has loaded, the calculators are fully offline-first. I've used the pace and BMI tools in airplane mode between flights — no spinner, no retry, just instant numbers. Same for sleep cycles if you're planning a shift.
Can my doctor rely on these numbers?
They're solid estimates using published formulas (WHO for BMI, Mifflin-St Jeor for BMR, CKD-EPI for GFR) but they're not a diagnosis. Think of them as a conversation starter: good for tracking trends, but your GP or nephrologist should interpret GFR, heart age or pregnancy dates with labs and context. We link the sources at the bottom for that reason.
How can I share my result with a trainer or doctor?
Use 'Share Link' in the results panel. It builds a URL with your inputs — for example BMI 70kg/175cm — so they see exactly what you entered. No data is stored on our side, the link just carries the numbers.
Sources & References
How this calculator is maintained
This calculator is written and maintained by Davide Coronese, independent developer and founder of CalcTracker.
Methodology: every formula is checked against official publications and validated by an automated test suite before release. Health, tax and finance pages cite the exact sources they rely on.
Found an error? Contact us — verified corrections ship within 24 hours.