{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"centrifuge-rcf-rpm"},"result":{"entity_type":"calculator","id":"centrifuge-rcf-rpm","calculator_id":"centrifuge-rcf-rpm","canonical_url":"https://tttkmbb.com/science/centrifuge-rcf-rpm","name":"Centrifuge RCF / RPM Converter","title":"Centrifuge RCF to RPM Converter – Relative Centrifugal Force (×g) from Rotor Speed and Radius","category":"science","category_name":"Biology, Earth & Space","tool_name":"convert_centrifuge_rcf_rpm","featured_mcp_tool":false,"description":"Converts between rotor speed (rpm) and relative centrifugal force (RCF, in multiples of g) for a given rotor radius with RCF = 1.118 × 10⁻⁵ × r_cm × rpm², solving whichever of the two is not given.","use_when":"A protocol specifies a centrifugation force in ×g and you need the rpm for your rotor, or you know the rpm and radius and need the force applied to the sample.","do_not_use_when":"You need the centripetal force in newtons on a specific mass (use centripetal-force), or sedimentation times and k-factors of ultracentrifuge rotors.","inputs":[{"name":"rpm","label":"Rotor speed","type":"number","unit":"rpm","required":false,"max":200000,"exclusive_min":0,"description":"Revolutions per minute. Give rpm or rcf_g, not both.","example":3000},{"name":"rcf_g","label":"Relative centrifugal force","type":"number","unit":"×g","required":false,"max":2000000,"exclusive_min":0,"description":"Force in multiples of standard gravity (×g). Give rcf_g or rpm, not both."},{"name":"radius_cm","label":"Rotor radius","type":"number","unit":"cm","required":true,"max":100,"exclusive_min":0,"description":"Distance from the rotor axis to the point of interest in the tube (r_max = bottom of the tube, r_min = top; protocols usually mean r_max or r_average).","example":10}],"outputs":[{"name":"rcf_g","label":"Relative centrifugal force","type":"number","unit":"×g","decimals":1,"description":"1.118 × 10⁻⁵ × radius_cm × rpm²."},{"name":"rpm","label":"Rotor speed","type":"number","unit":"rpm","decimals":0,"description":"√(rcf_g / (1.118 × 10⁻⁵ × radius_cm))."},{"name":"radius_cm","label":"Radius used","type":"number","unit":"cm","decimals":2,"description":"Rotor radius the conversion refers to."},{"name":"angular_velocity_rad_s","label":"Angular velocity","type":"number","unit":"rad/s","decimals":2,"description":"rpm × 2π / 60."},{"name":"note","label":"Note","type":"string","decimals":4,"description":"Which quantity was solved and how the radius affects the result."}],"input_schema":{"type":"object","properties":{"rpm":{"description":"Revolutions per minute. Give rpm or rcf_g, not both. Unit: rpm.","type":"number","maximum":200000,"exclusiveMinimum":0,"examples":[3000],"x-unit":"rpm"},"rcf_g":{"description":"Force in multiples of standard gravity (×g). Give rcf_g or rpm, not both. Unit: ×g.","type":"number","maximum":2000000,"exclusiveMinimum":0,"x-unit":"×g"},"radius_cm":{"description":"Distance from the rotor axis to the point of interest in the tube (r_max = bottom of the tube, r_min = top; protocols usually mean r_max or r_average). Unit: cm.","type":"number","maximum":100,"exclusiveMinimum":0,"examples":[10],"x-unit":"cm"}},"additionalProperties":false,"required":["radius_cm"]},"output_schema":{"type":"object","properties":{"rcf_g":{"description":"1.118 × 10⁻⁵ × radius_cm × rpm². Unit: ×g.","type":"number","x-unit":"×g"},"rpm":{"description":"√(rcf_g / (1.118 × 10⁻⁵ × radius_cm)). Unit: rpm.","type":"number","x-unit":"rpm"},"radius_cm":{"description":"Rotor radius the conversion refers to. Unit: cm.","type":"number","x-unit":"cm"},"angular_velocity_rad_s":{"description":"rpm × 2π / 60. Unit: rad/s.","type":"number","x-unit":"rad/s"},"note":{"description":"Which quantity was solved and how the radius affects the result.","type":"string"}}},"formula":"RCF (×g) = 1.118 × 10⁻⁵ × radius_cm × rpm²; rpm = √(RCF / (1.118 × 10⁻⁵ × radius_cm)); ω = 2π × rpm / 60","method":"RCF = ω² r / g with g = 9.80665 m/s², which reduces to the 1.118 × 10⁻⁵ constant for r in cm and speed in rpm. Because RCF is proportional to the radius, the same rpm gives different forces at the top and bottom of a tube; use the radius your protocol refers to (usually r_max).","sources":[{"name":"Wikipedia – Centrifuge","url":"https://en.wikipedia.org/wiki/Centrifuge","type":"reference","retrieved_at":"2026-09-24"},{"name":"Wikipedia – Centrifugation","url":"https://en.wikipedia.org/wiki/Centrifugation","type":"reference","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"3,000 rpm at 10 cm radius","inputs":{"rpm":3000,"radius_cm":10},"expected":{"rcf_g":1006.2,"rpm":3000,"angular_velocity_rad_s":314.16},"url":"https://tttkmbb.com/api/v1/calculate/centrifuge-rcf-rpm?rpm=3000&radius_cm=10"},{"name":"1,000 ×g needed at 8 cm radius","inputs":{"rcf_g":1000,"radius_cm":8},"expected":{"rpm":3344,"rcf_g":1000},"url":"https://tttkmbb.com/api/v1/calculate/centrifuge-rcf-rpm?rcf_g=1000&radius_cm=8"}],"faq":[{"q":"Why do protocols give ×g instead of rpm?","a":"The force on the sample depends on both speed and rotor radius, so only RCF (×g) is transferable between centrifuges; convert it to rpm with your rotor's radius."},{"q":"Which radius should I use?","a":"The maximum radius (bottom of the tube) is the usual reference for pelleting; some manufacturers quote the average radius. Check the rotor specification sheet."},{"q":"Where does 1.118 × 10⁻⁵ come from?","a":"RCF = ω² r / g with ω = 2π × rpm / 60 and r in metres; converting r to centimetres and dividing by 9.80665 m/s² gives (2π/60)² / (100 × 9.80665) = 1.118 × 10⁻⁵."}],"tags":["rcf to rpm","rpm to rcf","relative centrifugal force","centrifuge","g force","rotor radius"],"related":[{"calculator_id":"centripetal-force","reason":"Centripetal force and acceleration in newtons and m/s² for a mass at that radius."},{"calculator_id":"hemocytometer-count","reason":"Count the cells after pelleting and resuspending."},{"calculator_id":"frequency","reason":"Convert rpm to hertz or radians per second."}],"links":{"html":"https://tttkmbb.com/science/centrifuge-rcf-rpm","markdown":"https://tttkmbb.com/science/centrifuge-rcf-rpm.md","json":"https://tttkmbb.com/science/centrifuge-rcf-rpm.json","api":"https://tttkmbb.com/api/v1/calculate/centrifuge-rcf-rpm","schema":"https://tttkmbb.com/api/v1/calculators/centrifuge-rcf-rpm","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T08:04:13Z","next_actions":[{"tool":"run_calculator","calculator_id":"centrifuge-rcf-rpm","reason":"Run Centrifuge RCF / RPM Converter with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/science/centrifuge-rcf-rpm.md"}}