{
  "slug": "one-rep-max-lombardi",
  "title": "One-Rep Max Calculator (Lombardi Formula)",
  "category": "Strength Training",
  "category_slug": "strength-training",
  "tier": 2,
  "summary": "Estimate your one-rep max from submaximal lifts using the Lombardi formula.",
  "description": "This calculator estimates your one-rep max (1RM) from a submaximal lift using the Lombardi formula, published in 1989 and derived from resistance-trained populations. It accepts the weight lifted and the number of repetitions performed, then applies the equation 1RM = weight × reps^0.10 to produce an estimated maximal strength value in kilograms or pounds. The Lombardi method models each additional repetition's contribution to predicted 1RM through a fixed exponent, offering a population-average estimate suitable for programming and tracking progress in strength training.",
  "page_url": "https://fitmetriclab.com/en/tools/strength-training/one-rep-max-lombardi/",
  "api_url": "https://fitmetriclab.com/api/tools/one-rep-max-lombardi.json",
  "formula": {
    "id": "one_rep_max_lombardi",
    "expression": "\\text{1RM} = w \\times r^{0.10}",
    "variables": [
      {
        "symbol": "w",
        "description": "Weight in kg"
      },
      {
        "symbol": "r",
        "description": "Reps performed"
      }
    ]
  },
  "inputs": [
    {
      "id": "weight_kg",
      "label": "Weight",
      "type": "number",
      "unit": "kg",
      "default": 75,
      "min": 20,
      "max": 300,
      "step": 0.1
    },
    {
      "id": "reps",
      "label": "Reps",
      "type": "number",
      "unit": "reps",
      "default": 5,
      "min": 1,
      "max": 20,
      "step": 1
    }
  ],
  "worked_example": {
    "inputs": {
      "weight_kg": 75,
      "reps": 5
    },
    "expected_output": "88.1 kg"
  },
  "result_summary_template": "For a lift performed with {weight_kg} kg for {reps} repetitions, the Lombardi formula estimates a one-rep max of {result}.",
  "methodology": "Applies the Lombardi (1989) formula: 1RM = weight × reps^0.10. The exponent of 0.10 models the contribution of each additional repetition to estimated maximal strength. Originally derived from submaximal testing data in resistance-trained populations.",
  "sources": [
    {
      "label": "Lombardi BJ. Beginning Weight Training: The Safe and Effective Way. Dubuque, IA: W.C. Brown Publishers; 1989.",
      "url": ""
    },
    {
      "label": "LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. J Strength Cond Res. 1997;11(4):211-213.",
      "url": "https://pubmed.ncbi.nlm.nih.gov/27367024/"
    },
    {
      "label": "Reynolds JM, Gordon TJ, Robergs RA. Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry. J Strength Cond Res. 2006;20(3):584-592.",
      "url": "https://pubmed.ncbi.nlm.nih.gov/16937972/"
    }
  ],
  "faqs": [
    {
      "question": "What makes the Lombardi formula different from other 1RM equations?",
      "answer": "Lombardi uses a fixed exponent of 0.10, which produces a gentler progression than formulas with linear or higher-order polynomial terms. This tends to yield more conservative estimates at higher repetition ranges compared to Epley or Brzycki equations."
    },
    {
      "question": "Why does the formula use an exponent of 0.10?",
      "answer": "The 0.10 exponent was derived empirically by Lombardi in 1989 from regression analysis of submaximal lift data. It reflects the average rate at which repetitions predict increases in estimated maximal load across the sample population studied."
    },
    {
      "question": "Can this formula be used for any lift?",
      "answer": "The Lombardi equation is exercise-agnostic in its mathematical structure, but accuracy varies by movement. Compound lifts with shorter ranges of motion (e.g., bench press, squat) tend to align more closely with the formula's assumptions than isolation exercises or movements with long eccentric phases."
    },
    {
      "question": "How does fatigue affect the estimate?",
      "answer": "Cumulative fatigue from prior sets, training sessions, or inadequate recovery can reduce the number of repetitions completed at a given weight, leading the formula to underestimate true 1RM. The equation assumes the submaximal set represents a near-maximal effort under rested conditions."
    },
    {
      "question": "What repetition range produces the most reliable estimates?",
      "answer": "Research comparing predicted and measured 1RM values suggests that sets of 3 to 8 repetitions typically yield estimates within 5–10% of actual maximal lifts when form is consistent and sets are taken to or near failure. Estimates from sets above 12 reps show greater variance."
    }
  ],
  "related_tools": [
    {
      "slug": "one-rep-max-brzycki",
      "title": "One-Rep Max Calculator (Brzycki Formula)",
      "api_url": "https://fitmetriclab.com/api/tools/one-rep-max-brzycki.json",
      "page_url": "https://fitmetriclab.com/en/tools/strength-training/one-rep-max-brzycki/"
    },
    {
      "slug": "one-rep-max-comparison",
      "title": "Multi-Formula 1RM Comparison Calculator",
      "api_url": "https://fitmetriclab.com/api/tools/one-rep-max-comparison.json",
      "page_url": "https://fitmetriclab.com/en/tools/strength-training/one-rep-max-comparison/"
    },
    {
      "slug": "one-rep-max-epley",
      "title": "One-Rep Max Calculator (Epley Formula)",
      "api_url": "https://fitmetriclab.com/api/tools/one-rep-max-epley.json",
      "page_url": "https://fitmetriclab.com/en/tools/strength-training/one-rep-max-epley/"
    }
  ],
  "last_updated": "2026-04-22",
  "price": {
    "value": 0,
    "currency": "USD"
  },
  "runs_in_browser": true,
  "disclaimer": "Educational estimate produced from a published formula. Not medical, nutritional, or training advice. Calculations are deterministic — apply the formula to the inputs to reproduce the result."
}