Estimate your 1RM from any set with five formulas at once, then read a full %1RM training-load table — kg or lb, browser-only
- Runs locally
- Category Calculator
- Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.
By formula
Training load table
Percentages of your estimated 1RM, with reps you can expect at each load.
| % of 1RM | Weight | Est. reps |
|---|---|---|
| 100% | 114.5 kg | ~1 rep |
| 95% | 109 kg | ~2 reps |
| 90% | 103 kg | ~3 reps |
| 85% | 97.5 kg | ~5 reps |
| 80% | 91.5 kg | ~8 reps |
| 75% | 86 kg | ~10 reps |
| 70% | 80 kg | ~13 reps |
| 65% | 74.5 kg | ~16 reps |
| 60% | 68.5 kg | ~20 reps |
| 55% | 63 kg | ~25 reps |
| 50% | 57.5 kg | ~30 reps |
What this tool does
Enter a weight you lifted and how many reps you got, and this calculator estimates your one-rep max five different ways at the same time — Epley, Brzycki, Lombardi, Lander and O'Conner — then shows the average, which in the 3-6 rep range tracks a real tested single better than any one equation. No formula is universally "correct", so instead of hiding the disagreement behind one number, you see the full spread and decide. From the estimate it builds the training-load table every program runs on: 100%, 95%, 90% all the way down to 50% of your 1RM, each row showing the exact weight to load and the reps you can expect to hit there. A reverse mode flips this — type a target 1RM and get the working weight for every rep count from 1 to 12, so planning a 5x5 or a heavy triple takes one entry. Switch kg and lb anytime; weights round to gym-friendly increments (0.5 kg, 1 lb), every result has a shareable link, and all the math runs in your browser with nothing sent anywhere.
Tool details
- Input
- Text + Numbers
- The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
- Output
- Live result + Copy
- The result area focuses on usable output, with copy, download, or preview actions when supported.
- Privacy
- Browser-side processing
- The main tool logic does not call an external API, so inputs normally stay in the current tab.
- Save / share
- Shareable URL state
- Key settings are encoded in the URL so another person can reopen the same setup.
- Performance budget
- Initial JS <= 10 KB
- No WASM budget is declared, keeping the tool quick to open on mobile.
- Best fit
- Calculator · Student
- Category and role tags drive related tools, internal links, and quick fit checks.
How to use
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1. Input
Paste or drop your content into the tool panel.
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2. Process
Click the button. All processing is local in your browser.
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3. Copy / Download
Copy the result or download to disk in one click.
How One-Rep Max Calculator fits into your work
Use it for fast estimates, comparisons, and planning numbers before you make the final call.
Calculation jobs
- Getting a realistic range before a purchase, plan, workout, or schedule decision.
- Comparing scenarios by changing one input at a time.
- Turning rough assumptions into a number you can discuss.
Calculation checks
- Double-check units, dates, rates, and rounding assumptions.
- Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
- Save the inputs that produced an important result so you can reproduce it later.
Good next steps
These links move the current task into a more complete workflow.
- 1 Barbell Plate Calculator Target weight → exactly which plates to slide on each end — kg & lb, with a live barbell diagram — browser-only Open
- 2 TDEE Calculator TDEE calculator — BMR × activity factor, with cut/bulk calorie targets and projected weekly weight change. Open
- 3 Calories Burned Calculator MET-based calorie burn for 30+ activities — running, cycling, swimming, HIIT, housework — stack and total — browser-only Open
Real-world use cases
Set working weights for a new 5x5 block
You just hit 100 kg for 5 clean reps on squats and your program calls for 5x5 at 80% next week. You enter 100 kg and 5 reps, read the average 1RM (around 117 kg), then drop to the load table and find the 80% row — roughly 93 kg. Because the table rounds to 0.5 kg increments, that is a number you can actually load with standard plates, no mental math at the rack while a queue forms behind you.
Pick a sane opener for a meet attempt
You are planning your first powerlifting meet and need an opening attempt you will not miss. Your best recent set was 140 kg for 3 reps. You enter it, see an estimated 1RM near 154 kg, and use the load table to set your opener at about 90% (≈139 kg) — heavy enough to count, conservative enough that nerves and a new platform will not cost you the lift. The spread between formulas also tells you how confident to be.
Translate a coach's percentage prescription
Your coach texts "work up to a heavy single, then 3x5 at 75%". You take your top single straight into the tool (1 rep equals the weight), switch to the percentage table, and read the 75% row directly. No spreadsheet, no doing 0.75 times an awkward number in your head between sets — the weight to load is already on screen, rounded to the plates you have.
Plan loads in pounds on a kilo-logged lift
You log your training in kilograms but you are travelling and the gym only has pound-loaded bars. You enter your last set in kg, then tap the lb toggle — the entire estimate and load table reconverts to pounds rounded to 1 lb, so you can load the unfamiliar bar without doing conversions on your phone between every set.
Check a rep PR against your old max
You used to single 120 kg and today you got 100 kg for 6 reps for the first time. Entering 100 kg and 6 reps gives an estimated 1RM around 118 kg — so even though you did not test a single, that rep PR strongly suggests your max has held or climbed. The five-formula spread shows the estimate sits close to your old number, not a fluke of one equation.
Common pitfalls
Estimating a max from a high-rep burnout set. Past ~8 reps every formula drifts; use 3-5 reps for a tight number.
Treating one formula as truth. Epley reads high, O'Conner low — the honest read is the average plus the spread.
Chasing the exact decimal in the table. Weights are rounded to plate-friendly steps on purpose; the estimate is not that precise.
Privacy
Every estimate — the five formulas, the average, the percentage table and the reverse target table — is plain JavaScript that runs in your browser tab. Your weights and reps never leave the page, nothing is logged, and there is no external API call. The one thing to know: the shareable link encodes your inputs in the query string (e.g. ?weight=100&reps=5&unit=kg), so if you paste a share link somewhere, the destination server's log will record those numbers. Training data is harmless to share; there is nothing sensitive here, but that is why the URL changes as you type.
FAQ
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