{
  "slug": "pr-progression",
  "title": "Personal Record Progression Calculator",
  "category": "Progress Tracking",
  "category_slug": "progress-tracking",
  "tier": 3,
  "summary": "Calculate average strength gain per personal record to track absolute progression step size.",
  "description": "This calculator computes the average strength gain per personal record by dividing total accumulated weight increase by the number of PR events recorded. It requires two inputs—the count of personal records achieved and the total gain in kilograms—and outputs an average progression step size in kg/PR. The method treats all PRs equally without weighting by recency or adjusting for baseline strength, providing a simple metric to track absolute progression rate over time.",
  "page_url": "https://fitmetriclab.com/en/tools/progress-tracking/pr-progression/",
  "api_url": "https://fitmetriclab.com/api/tools/pr-progression.json",
  "formula": {
    "id": "pr_progression",
    "expression": "\\text{Avg gain per PR} = \\frac{\\Delta_{total}}{n_{PR}}",
    "variables": [
      {
        "symbol": "n",
        "description": "Number of PR entries"
      },
      {
        "symbol": "\\Delta_{total}",
        "description": "Total gain in kg"
      }
    ]
  },
  "inputs": [
    {
      "id": "pr_history_count",
      "label": "PR Count",
      "type": "number",
      "unit": "",
      "default": 4,
      "min": 1,
      "max": 50,
      "step": 1
    },
    {
      "id": "total_gain_kg",
      "label": "Total Gain",
      "type": "number",
      "unit": "kg",
      "default": 10,
      "min": 0,
      "max": 200,
      "step": 0.1
    }
  ],
  "worked_example": {
    "inputs": {
      "pr_history_count": 4,
      "total_gain_kg": 10
    },
    "expected_output": "2.50 kg/PR"
  },
  "result_summary_template": "With {pr_history_count} personal records and a total gain of {total_gain_kg} kg, the average gain per PR is {result}.",
  "methodology": "Average gain per PR = total_gain_kg ÷ pr_history_count. This ratio divides cumulative strength increase by the number of PR events, yielding an average step size in kg/PR. The method treats all PRs equally without weighting by recency or baseline normalization.",
  "sources": [
    {
      "label": "Haff GG, Triplett NT. Essentials of Strength Training and Conditioning, 4th ed. Human Kinetics. 2016.",
      "url": "https://us.humankinetics.com/products/essentials-of-strength-training-and-conditioning-4th-edition"
    },
    {
      "label": "Israetel M, Hoffmann J, Smith CW. Scientific Principles of Strength Training. Juggernaut Training Systems. 2015.",
      "url": "https://www.jtsstrength.com/product/scientific-principles-of-strength-training/"
    },
    {
      "label": "Zourdos MC, et al. Novel Resistance Training–Specific RPE Scale Measuring Repetitions in Reserve. J Strength Cond Res. 2016;30(1):267-275.",
      "url": "https://pubmed.ncbi.nlm.nih.gov/26049792/"
    }
  ],
  "faqs": [
    {
      "question": "Why does this calculator use absolute kg/PR instead of percentage change?",
      "answer": "The tool reports raw gain per PR event to track step size without normalizing to starting strength. A 5 kg/PR average indicates consistent absolute progression regardless of whether the lifter started at 100 kg or 200 kg. Percentage-based metrics require a defined baseline 1RM input, which this calculator does not collect."
    },
    {
      "question": "Can I compare kg/PR across different lifts?",
      "answer": "Comparing kg/PR between exercises like bench press and deadlift is less informative because each lift involves different muscle groups and typical load ranges. The metric works best for tracking a single exercise over time within one individual's training history."
    },
    {
      "question": "Does the calculator account for time between PRs?",
      "answer": "No. The tool divides total gain by PR count without considering days, weeks, or months elapsed. A lifter who achieves 4 PRs in two months and another who takes six months both see the same kg/PR if absolute gains match."
    },
    {
      "question": "What counts as a PR for this calculation?",
      "answer": "The input asks for the number of distinct PR events logged. Some lifters record every new top-set weight as a PR; others reserve the designation for competition or true max-attempt tests. Consistent logging criteria within a training cycle yield more interpretable averages."
    },
    {
      "question": "How does bodyweight change affect this metric?",
      "answer": "The calculator does not adjust for bodyweight. A lifter who gains 15 kg bodyweight while adding 30 kg to a squat PR will see the same kg/PR result as someone who maintained weight. Relative strength (gain per kg bodyweight) requires a separate calculation."
    }
  ],
  "related_tools": [
    {
      "slug": "strength-progression",
      "title": "Strength Progression Calculator",
      "api_url": "https://fitmetriclab.com/api/tools/strength-progression.json",
      "page_url": "https://fitmetriclab.com/en/tools/progress-tracking/strength-progression/"
    },
    {
      "slug": "time-to-goal-weight",
      "title": "Time-to-Goal Calculator (Weight)",
      "api_url": "https://fitmetriclab.com/api/tools/time-to-goal-weight.json",
      "page_url": "https://fitmetriclab.com/en/tools/progress-tracking/time-to-goal-weight/"
    },
    {
      "slug": "weekly-volume-comparison",
      "title": "Weekly Volume Comparison Calculator",
      "api_url": "https://fitmetriclab.com/api/tools/weekly-volume-comparison.json",
      "page_url": "https://fitmetriclab.com/en/tools/progress-tracking/weekly-volume-comparison/"
    }
  ],
  "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."
}