One Rep Max Calculator

Calculators REST API MCP

Estimate a one-rep max (1RM) from a weight lifted for a number of reps, using Brzycki, Epley, Lander, Lombardi, Mayhew, O'Conner, and Wathen formulas. Returns the chosen formula result, every formula result, and a training-weight table (100% to 60%) with rep ranges and zones.

This page documents the MCP tool findutils:one_rep_max_calculator. See the REST reference →

Use in the browser View as Markdown

Call it over MCP

Tool name findutils:one_rep_max_calculator · no API keys · 120 requests/min per IP

Claude Code

claude mcp add findutils --transport http https://mcp.findutils.com/

Claude Desktop — claude_desktop_config.json

{
  "mcpServers": {
    "findutils": {
      "url": "https://mcp.findutils.com/"
    }
  }
}

Raw JSON-RPC (any MCP client) — verified example

curl -X POST https://mcp.findutils.com/ \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/call",
    "params": {
      "name": "one_rep_max_calculator",
      "arguments": {
        "weight": 100,
        "reps": 5
      }
    }
  }'

Input schema

Argument	Type	Required	Description
weight	number	yes	Weight lifted, in the chosen unit.
reps	integer	yes	Reps performed with that weight (1-30).
unit	string (kg \| lbs)	no	Weight unit, echoed back in the result. Default: "kg".
formula	string (brzycki \| epley \| lander \| lombardi \| mayhew \| oconner \| wathen)	no	Formula used for the headline one_rep_max. Default: "brzycki".

Example arguments (verified)

{
  "weight": 100,
  "reps": 5
}

Also a REST endpoint

The same tool answers plain HTTP at POST /api/tools/one-rep-max-calculator/execute — no key, 60 requests/min.

Open the REST reference for One Rep Max Calculator →

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