{
  "slug": "speed-converter",
  "title": "Speed Converter (MPH to km/h to m/s)",
  "category": "Conversions",
  "category_slug": "conversions",
  "tier": 2,
  "summary": "Convert running and cycling speeds between mph, km/h, and m/s using international standard factors.",
  "description": "This calculator converts running and cycling speeds between miles per hour (mph), kilometres per hour (km/h), and metres per second (m/s) using internationally standardised conversion factors. It accepts a speed value in either mph or km/h as input and returns the equivalent speed in the other two units. The tool applies the exact factor 1 mile = 1.609344 km as maintained by the International Bureau of Weights and Measures (BIPM) and the SI definition 1 m/s = 3.6 km/h, ensuring precise conversions for training logs, race results, and performance tracking.",
  "page_url": "https://fitmetriclab.com/en/tools/conversions/speed-converter/",
  "api_url": "https://fitmetriclab.com/api/tools/speed-converter.json",
  "formula": {
    "id": "speed_converter",
    "expression": "v_{kmh} = v_{mph} \\times 1.609344, \\quad v_{m/s} = \\frac{v_{kmh}}{3.6}",
    "variables": [
      {
        "symbol": "v_{mph}",
        "description": "Speed in mph"
      },
      {
        "symbol": "v_{kmh}",
        "description": "Speed in km/h"
      }
    ]
  },
  "inputs": [
    {
      "id": "mph",
      "label": "Speed",
      "type": "number",
      "unit": "mph",
      "default": 6,
      "min": 0,
      "max": 120,
      "step": 0.1
    },
    {
      "id": "kmh",
      "label": "Speed",
      "type": "number",
      "unit": "km/h",
      "default": 10,
      "min": 0,
      "max": 200,
      "step": 0.1
    }
  ],
  "worked_example": {
    "inputs": {
      "mph": 6,
      "kmh": 10
    },
    "expected_output": "9.66 km/h"
  },
  "result_summary_template": "Converting a speed of {mph} mph or {kmh} km/h between units using standard conversion factors yields {result}.",
  "methodology": "Converts between mph, km/h, and m/s using the international standard 1 mile = 1.609344 km (KM_PER_MILE) and the SI definition 1 m/s = 3.6 km/h. These exact conversion factors are maintained by the International Bureau of Weights and Measures (BIPM).",
  "sources": [
    {
      "label": "International Bureau of Weights and Measures (BIPM). The International System of Units (SI). 9th ed. 2019.",
      "url": "https://www.bipm.org/en/publications/si-brochure"
    },
    {
      "label": "National Institute of Standards and Technology (NIST). Guide for the Use of the International System of Units (SI). Special Publication 811. 2008.",
      "url": "https://www.nist.gov/pml/special-publication-811"
    },
    {
      "label": "International Yard and Pound Agreement. Federal Register Notice. National Bureau of Standards. 1959.",
      "url": "https://www.govinfo.gov/content/pkg/FR-1959-06-30/pdf/FR-1959-06-30.pdf"
    }
  ],
  "faqs": [
    {
      "question": "Why does 1 mile equal exactly 1.609344 kilometers?",
      "answer": "The international mile is defined as exactly 1,609.344 meters by treaty. This fixed ratio ensures consistent conversion across all scientific, athletic, and commercial contexts. The definition traces to the International Yard and Pound Agreement of 1959."
    },
    {
      "question": "How do I convert m/s back to mph or km/h?",
      "answer": "Multiply m/s by 3.6 to get km/h, or multiply m/s by 2.23694 to get mph. The tool displays m/s as a secondary result whenever mph or km/h is entered, but does not currently accept m/s as a direct input."
    },
    {
      "question": "Are GPS watch speeds accurate enough to rely on these conversions?",
      "answer": "Consumer GPS devices typically report speed with ±2–5% error under good satellite conditions. The conversion itself is exact, but input precision depends on the measurement device. Track-based timing or calibrated treadmills generally provide higher accuracy."
    },
    {
      "question": "Why do treadmills sometimes show speeds that don't match my GPS watch after conversion?",
      "answer": "Treadmill belt calibration can drift over time, and some models round displayed speeds. Additionally, slight incline settings alter effective running speed without changing the belt speed. GPS error outdoors also contributes to mismatches when comparing converted values."
    },
    {
      "question": "Can I use this for cycling power meter speed data?",
      "answer": "Yes. The conversion factors apply to any speed measurement regardless of mode of locomotion. Power meters typically derive speed from wheel or hub sensors, which may differ slightly from GPS-based speed due to tire circumference settings and calibration."
    }
  ],
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      "api_url": "https://fitmetriclab.com/api/tools/energy-converter.json",
      "page_url": "https://fitmetriclab.com/en/tools/conversions/energy-converter/"
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      "slug": "pace-converter-multi",
      "title": "Pace Converter (Multiple Units)",
      "api_url": "https://fitmetriclab.com/api/tools/pace-converter-multi.json",
      "page_url": "https://fitmetriclab.com/en/tools/conversions/pace-converter-multi/"
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    {
      "slug": "volume-converter",
      "title": "Hydration Volume Converter (L to fl oz)",
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  ],
  "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."
}