One Rep Max Calculator

Estimate one-repetition maximum using the Epley formula. Enter your values below to calculate instantly, then use the explanation and example to understand the result.

Enter your values

Estimated 1RM

— kg

What this One Rep Max Calculator does

Estimate one-repetition maximum using the Epley formula. It is designed to give a quick answer while still showing enough context to understand what the number means and what assumptions can affect it.

Inputs usedWeight lifted (kg), Repetitions

Main resultEstimated 1RM (kg)

Runs locallyCalculation is performed in your browser; the page does not need an account to calculate.

How to use the calculator

Enter each value using the unit shown beside the field.
Select คำนวณ to update the result.
Read the result together with the unit, assumptions and interpretation on this page.
Change one input at a time when comparing scenarios so you can see what actually drives the answer.

How the calculation works

Estimate one-repetition maximum using the Epley formula. The calculator applies the relationship defined for this tool to the values you enter and formats the result for readability.

ตัวอย่างการคำนวณ

With the example inputs Weight lifted = 80 kg, Repetitions = 8, the calculator returns approximately 101.333 kg.

How to interpret the result

Sports estimates are planning aids and can vary with terrain, technique, fitness, environmental conditions and measurement accuracy.

Use safe training practices and professional guidance where health or injury risk is involved.

Accuracy, inputs and rounding

The arithmetic is deterministic: the same valid inputs produce the same answer. A realistic result still depends on the quality of the values you enter. XpressCalculator keeps units next to inputs and rounds displayed results for readability. When precision matters, keep more source precision and avoid rounding intermediate values.

Important: This page is an informational calculator. For medical, financial, electrical, engineering, tax, legal or safety-critical decisions, verify the assumptions and current rules with an authoritative source or qualified professional.

คำถามที่พบบ่อย

What does the One Rep Max Calculator calculate?

Estimate one-repetition maximum using the Epley formula.

Why can another calculator show a different answer?

Different calculators may use different formulas, defaults, rounding rules, unit conventions or assumptions. Match the inputs and method before comparing results.

Can I use decimal values?

Yes, where the input field accepts numbers. Use the precision supported by your source data rather than adding unnecessary decimal places.

Does XpressCalculator save the values I enter?

The calculation logic on this page runs in your browser. Standard site analytics or advertising services may still process technical usage data as described in the Privacy Policy.

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Editorial review: Formula, units, interface and explanatory content reviewed for consistency on September 4, 2026. See our วิธีการคำนวณ and Accuracy Policy.