About e1RM

e1RM is an indie strength training calculator built by a lifter who got tired of single-formula apps. The "1RM" you see in most online calculators is technically an e1RM — an estimated one rep max derived from a submaximal set. We named the site after the thing we're actually calculating.

What makes e1RM different

• Seven formulas, side by side. Epley, Brzycki, Lombardi, O'Conner, Mayhew, Wathan, and Lander. The spread between them tells you how much uncertainty to expect from your input set.
• Cite-able sources. Every formula links to its original publication year and paper. Every strength standard explains how it was calculated. No magic numbers.
• No signup, no ads, no email gate. Calculators stay free and stay open.

Who builds this

e1RM is edited by maol, an indie developer and recreational lifter who uses percentage-based barbell training in his own programming. The site is intentionally narrow: it focuses on estimated maxes, training maxes, plate loading, RPE/RIR, nutrition planning, and powerlifting scoring. It does not try to be a medical product, coaching platform, or supplement site.

The author background is practical rather than clinical: years of building small web tools, training with barbell percentage blocks, and maintaining source-driven calculators where the formula is visible in the page. That is why e1RM treats every calculated max as an estimate and shows uncertainty instead of presenting one number as truth.

The calculator math is reviewed against published equations and public references before it is shipped. For example, the one-rep-max tools compare seven common formulas instead of hiding uncertainty behind a single output. Nutrition calculators use Mifflin-St Jeor as a planning estimate, then explain that real intake should be adjusted from bodyweight trends. Powerlifting calculators label DOTS and Wilks as comparison scores, not training advice.

Editorial standards

Every calculator page should answer four questions: what the tool does, how the input is interpreted, where the math or convention comes from, and when the result should be treated conservatively. When a number depends on assumptions, e1RM tries to show the assumption directly rather than bury it in a black box.

Training content is written for healthy adult lifters and is reviewed for practical gym use: loadable plates, realistic rep ranges, RPE/RIR context, and conservative training maxes. Nutrition content is framed as planning support and includes medical-advice boundaries for people with medical conditions, pregnancy, age under 18, or a history of disordered eating.

Source policy

e1RM prefers original papers, PubMed records, federation or database references, and well-maintained public data sources. If a page uses a formula, coefficient, or standard, the page should name the source and explain the limitation. If a source is historical and not easily available online, the page should still identify the publication and avoid pretending the output is more precise than the evidence allows.

Ad and affiliate policy

e1RM is built as a public reference asset first. Pages are written to be useful without signup, email capture, or affiliate gating. If display ads are added later, they should not block calculator inputs, hide formula text, or make source links harder to read.

Corrections and review

If a formula, coefficient, source, or explanation looks wrong, send the correction with the page URL and the reference you are using. Corrections are prioritized when they affect calculator output, safety boundaries, or page-level SEO metadata. Cosmetic suggestions are tracked separately so the core math stays stable.

Contact

Have a correction, a feature request, or a paper we should reference? Email [email protected].

Last reviewed

This About page and source policy were last reviewed on 2026-05-22.