{"id":100160,"date":"2026-02-15T20:21:41","date_gmt":"2026-02-15T20:21:41","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100160"},"modified":"2026-07-12T21:37:17","modified_gmt":"2026-07-12T21:37:17","slug":"motor-sizing-calculator","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/da\/calculators\/motor-sizing-calculator\/","title":{"rendered":"Motor-Shaft Load Point &#038; Candidate Capacity Worksheet"},"content":{"rendered":"\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Motor-Shaft Load Point and Candidate Capacity Worksheet\",\"description\":\"Convert one documented motor-shaft power or torque point and compare a user-specified candidate rating without automatic motor selection or invented starting multipliers.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/motor-sizing-calculator\/\",\"applicationCategory\":\"Engineering Reference\",\"operatingSystem\":\"Any\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"dateModified\":\"2026-07-12\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true}<\/script>\n<style>\n.ms-wrap{--ink:#17212b;--muted:#596775;--line:#d8e0e7;--soft:#f4f7f9;--blue:#1769aa;--blue2:#0f4f84;--warn:#fff7e5;max-width:980px;margin:0 auto;padding:20px 16px 46px;color:var(--ink);font:15px\/1.58 system-ui,-apple-system,\"Segoe UI\",sans-serif}.ms-wrap *{box-sizing:border-box}.ms-wrap [hidden]{display:none!important}.ms-hero{padding:38px 30px;border:1px solid var(--line);border-radius:18px;background:linear-gradient(135deg,#eef7ff,#fff 68%);box-shadow:0 10px 30px rgba(20,54,80,.07)}.ms-kicker{color:var(--blue);font-size:12px;font-weight:800;letter-spacing:.1em;text-transform:uppercase}.ms-hero h1{margin:8px 0 10px;font-size:clamp(27px,4vw,42px);line-height:1.12}.ms-lead{max-width:800px;margin:0;color:var(--muted);font-size:17px}.ms-badges{display:flex;flex-wrap:wrap;gap:8px;margin-top:18px}.ms-badge{padding:5px 10px;border:1px solid #b9d4e8;border-radius:999px;background:#fff;color:var(--blue2);font-size:12px;font-weight:700}.ms-main{margin-top:20px}.ms-panel,.ms-section{border:1px solid var(--line);border-radius:14px;background:#fff;box-shadow:0 5px 18px rgba(23,33,43,.05)}.ms-panel{padding:24px}.ms-panel h2,.ms-section h2{margin:0 0 8px;font-size:21px}.ms-note{margin:0 0 18px;color:var(--muted)}.ms-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}.ms-field{display:flex;flex-direction:column;gap:6px}.ms-wide{grid-column:1\/-1}.ms-label{font-weight:750}.ms-help{color:var(--muted);font-size:12px}.ms-input,.ms-select,.ms-textarea{width:100%;border:1.5px solid #bcc9d3;border-radius:8px;background:#fff;color:var(--ink);font:inherit;padding:10px 12px}.ms-textarea{min-height:100px;resize:vertical}.ms-input:focus,.ms-select:focus,.ms-textarea:focus{outline:3px solid rgba(23,105,170,.16);border-color:var(--blue)}.ms-error{min-height:24px;margin:14px 0 0;color:#a22727;font-weight:700}.ms-results{margin-top:20px;border:1px solid #b9d4e8;border-radius:12px;background:#f7fbff;padding:20px}.ms-rhead{display:flex;justify-content:space-between;gap:14px;align-items:flex-start}.ms-rtitle{font-size:19px;font-weight:800}.ms-rsub{max-width:590px;text-align:right;color:var(--muted);font-size:12px}.ms-rgrid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:11px;margin-top:14px}.ms-card{padding:14px;border:1px solid #d7e5f0;border-radius:10px;background:#fff}.ms-card h3{margin:0 0 7px;color:var(--muted);font-size:12px;text-transform:uppercase;letter-spacing:.04em}.ms-val{font-size:20px;font-weight:800;overflow-wrap:anywhere}.ms-unit{margin-top:3px;color:var(--muted);font-size:11px}.ms-alert{margin-top:18px;padding:15px 17px;border:1px solid #e8cf91;border-radius:10px;background:var(--warn);color:#624b13}.ms-section{margin-top:18px;padding:22px 24px}.ms-section p{margin:8px 0;color:var(--muted)}.ms-section ul{margin:10px 0 0;padding-left:22px;color:var(--muted)}.ms-code{font-family:ui-monospace,SFMono-Regular,Consolas,monospace;color:#113d62}.ms-table{width:100%;border-collapse:collapse;margin-top:12px}.ms-table th,.ms-table td{padding:10px;border:1px solid var(--line);text-align:left;vertical-align:top}.ms-table th{background:var(--soft)}.ms-section a{color:var(--blue2)}@media(max-width:680px){.ms-grid,.ms-rgrid{grid-template-columns:1fr}.ms-wide{grid-column:auto}.ms-hero{padding:26px 20px}.ms-panel,.ms-section{padding:19px}.ms-rhead{display:block}.ms-rsub{text-align:left;margin-top:5px}}@media print{.ms-wrap{max-width:none}.ms-hero,.ms-panel,.ms-section{box-shadow:none}}\n<\/style>\n<div class=\"ms-wrap\">\n<header class=\"ms-hero\"><div class=\"ms-kicker\">One mechanical shaft point \u00b7 documented project multiplier \u00b7 candidate comparison only<\/div><h1>Motor-Shaft Load Point &amp; Candidate Capacity Worksheet<\/h1><p class=\"ms-lead\">Convert one known shaft-power or shaft-torque point and compare it with a user-documented candidate rating. The worksheet does not select a motor,starter or VFD and does not create starting current,starting torque or \u201cstandard IEC size\u201d data.<\/p><div class=\"ms-badges\"><span class=\"ms-badge\">Starts blank<\/span><span class=\"ms-badge\">Exact2\u03c0 conversion<\/span><span class=\"ms-badge\">No hidden400V\/PF<\/span><span class=\"ms-badge\">No automatic recommendation<\/span><\/div><\/header>\n<main class=\"ms-main\"><section class=\"ms-panel\"><h2>Document the shaft load point<\/h2><p class=\"ms-note\">All quantities refer to the motor shaft at one steady operating point. Convert driven-equipment data through the documented gearbox\/coupling\/transmission model before using this worksheet.<\/p><form id=\"ms-form\" novalidate><div class=\"ms-grid\">\n<div class=\"ms-field ms-wide\"><label class=\"ms-label\" for=\"ms-basis\">Calculation basis<\/label><select class=\"ms-select\" id=\"ms-basis\"><option value=\"\">Select\u2026<\/option><option value=\"single-steady-motor-shaft-point\">Single steady motor-shaft load point;no acceleration or thermal sizing<\/option><\/select><\/div>\n<div class=\"ms-field\"><label class=\"ms-label\" for=\"ms-mode\">Known shaft quantity<\/label><select class=\"ms-select\" id=\"ms-mode\"><option value=\"\">Select\u2026<\/option><option value=\"shaft-power\">Mechanical shaft power P (kW)<\/option><option value=\"shaft-torque\">Mechanical shaft torque T (N\u00b7m)<\/option><\/select><\/div>\n<div class=\"ms-field\"><label class=\"ms-label\" for=\"ms-value\">Known value<\/label><input class=\"ms-input\" id=\"ms-value\" inputmode=\"decimal\" autocomplete=\"off\"><span class=\"ms-help\" id=\"ms-value-help\">Select a quantity.<\/span><\/div>\n<div class=\"ms-field\"><label class=\"ms-label\" for=\"ms-speed\">Shaft speed n (r\/min)<\/label><input class=\"ms-input\" id=\"ms-speed\" inputmode=\"decimal\" autocomplete=\"off\"><span class=\"ms-help\">Speed at this same load point.<\/span><\/div>\n<div class=\"ms-field\"><label class=\"ms-label\" for=\"ms-factor\">Documented capacity multiplier k<\/label><input class=\"ms-input\" id=\"ms-factor\" inputmode=\"decimal\" autocomplete=\"off\"><span class=\"ms-help\">Project\/OEM requirement,k\u22651;not an IEC or NEMA service factor invented here.<\/span><\/div>\n<div class=\"ms-field\"><label class=\"ms-label\" for=\"ms-candidate-power\">Candidate rated output (optional kW)<\/label><input class=\"ms-input\" id=\"ms-candidate-power\" inputmode=\"decimal\" autocomplete=\"off\"><span class=\"ms-help\">Manufacturer value for the candidate and applicable duty.<\/span><\/div>\n<div class=\"ms-field\"><label class=\"ms-label\" for=\"ms-candidate-speed\">Candidate rated speed (optional r\/min)<\/label><input class=\"ms-input\" id=\"ms-candidate-speed\" inputmode=\"decimal\" autocomplete=\"off\"><span class=\"ms-help\">Required together with candidate output.<\/span><\/div>\n<div class=\"ms-field ms-wide\"><label class=\"ms-label\" for=\"ms-source\">Load case,multiplier and candidate evidence<\/label><textarea class=\"ms-textarea\" id=\"ms-source\" maxlength=\"2400\" placeholder=\"Driven equipment and shaft location;torque-speed curve and load cycle;starts\/hour;inertia and acceleration time;transmission model;duty;ambient\/altitude\/cooling;supply and starter\/PDS;required multiplier source;candidate manufacturer curves and ratings\"><\/textarea><\/div>\n<\/div><p class=\"ms-error\" id=\"ms-error\" role=\"alert\"><\/p><\/form>\n<section class=\"ms-results\" id=\"ms-results\" hidden data-json=\"\"><div class=\"ms-rhead\"><div class=\"ms-rtitle\">Load-point arithmetic<\/div><div class=\"ms-rsub\" id=\"ms-summary\">\u2014<\/div><\/div><div class=\"ms-rgrid\">\n<article class=\"ms-card\"><h3>Angular speed<\/h3><div class=\"ms-val\" id=\"ms-r-omega\">\u2014<\/div><div class=\"ms-unit\">\u03c9=2\u03c0n\/60<\/div><\/article>\n<article class=\"ms-card\"><h3>Shaft load power<\/h3><div class=\"ms-val\" id=\"ms-r-power\">\u2014<\/div><div class=\"ms-unit\">mechanical power at this point<\/div><\/article>\n<article class=\"ms-card\"><h3>Shaft load torque<\/h3><div class=\"ms-val\" id=\"ms-r-torque\">\u2014<\/div><div class=\"ms-unit\">mean torque at this point<\/div><\/article>\n<article class=\"ms-card\"><h3>Documented required output<\/h3><div class=\"ms-val\" id=\"ms-r-required\">\u2014<\/div><div class=\"ms-unit\">P<sub>req<\/sub>=kP;planning arithmetic only<\/div><\/article>\n<article class=\"ms-card\"><h3>Required torque at this speed<\/h3><div class=\"ms-val\" id=\"ms-r-required-torque\">\u2014<\/div><div class=\"ms-unit\">kT at the recorded point<\/div><\/article>\n<article class=\"ms-card\"><h3>Candidate rated torque<\/h3><div class=\"ms-val\" id=\"ms-r-candidate-torque\">\u2014<\/div><div class=\"ms-unit\">candidate output\/candidate rated speed<\/div><\/article>\n<article class=\"ms-card\"><h3>Candidate capacity margin<\/h3><div class=\"ms-val\" id=\"ms-r-margin\">\u2014<\/div><div class=\"ms-unit\">candidate output\u2212documented required output<\/div><\/article>\n<article class=\"ms-card\"><h3>Candidate utilization<\/h3><div class=\"ms-val\" id=\"ms-r-util\">\u2014<\/div><div class=\"ms-unit\">P<sub>req<\/sub>\/candidate output;no pass\/fail<\/div><\/article>\n<article class=\"ms-card\"><h3>Candidate comparison<\/h3><div class=\"ms-val\" id=\"ms-r-candidate\">\u2014<\/div><div class=\"ms-unit\">numeric comparison only<\/div><\/article>\n<\/div><\/section>\n<div class=\"ms-alert\"><strong>Decision boundary:<\/strong> a non-negative capacity margin at one steady point does not prove adequate starting,acceleration,pull-up\/breakdown torque,thermal duty,overload,stall,braking,speed range,cooling,bearing,shaft,gearbox,converter,protection or process performance.<\/div><\/section><\/main>\n<section class=\"ms-section\"><h2>Equations and units<\/h2><table class=\"ms-table\"><thead><tr><th>Input basis<\/th><th>Independent relation<\/th><th>Output<\/th><\/tr><\/thead><tbody><tr><td>Known shaft power P in kW<\/td><td><span class=\"ms-code\">T=P\u00b71000\/[2\u03c0(n\/60)]<\/span><\/td><td>Mean shaft torque in N\u00b7m<\/td><\/tr><tr><td>Known shaft torque T in N\u00b7m<\/td><td><span class=\"ms-code\">P=T\u00b72\u03c0(n\/60)\/1000<\/span><\/td><td>Mechanical shaft power in kW<\/td><\/tr><tr><td>Documented multiplier k<\/td><td><span class=\"ms-code\">Preq=kP;Treq=kT<\/span><\/td><td>Arithmetic planning requirement at this same point<\/td><\/tr><\/tbody><\/table><p>The power\u2013torque conversion is ordinary mechanics,not an IEC motor-selection formula. The multiplier is supplied by the user from controlled project\/OEM evidence;the worksheet does not assign universal1.15\/1.25\/1.5 values.<\/p><\/section>\n<section class=\"ms-section\"><h2>Why one point cannot select a motor<\/h2><ul><li>Selection requires the full driven-load torque\u2013speed curve,breakaway torque,process transients,inertia,acceleration\/deceleration time,starts per hour and duty cycle.<\/li><li>Verify motor locked-rotor,pull-up,breakdown and accelerating torque against the load curve and supply\/starter conditions;do not replace those curves with a universal multiplier.<\/li><li>Check voltage,frequency,connection,ambient,altitude,cooling,enclosure,thermal class,permitted starts,overload and manufacturer tolerances.<\/li><li>For variable speed,verify the complete motor-converter-load system across constant-flux,field-weakening,low-speed cooling,regeneration and overload regions.<\/li><li>Oversizing is not automatically beneficial:it can worsen operating efficiency\/power factor and does not by itself extend bearing life.<\/li><\/ul><\/section>\n<section class=\"ms-section\"><h2>Standards and source boundary<\/h2><p><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/89961\" target=\"_blank\" rel=\"noopener\">IEC60034-1:2026,Edition15<\/a> is the current rotating-machine rating and performance standard and replaced2022. Exact duty,rating,tolerance and thermal requirements are <span class=\"ms-code\">NEEDS_LICENSED_SOURCE<\/span>;they are not replaced by this worksheet.<\/p><p><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/78133\" target=\"_blank\" rel=\"noopener\">IEC60034-12:2024,Edition4<\/a> has a specific scope for eight starting-performance designs of single-speed three-phase50\/60Hz cage induction motors up to1000V,intended for DOL or star-delta starting and based on S1 duty. It does not justify one universal DOL\/Y-\u0394\/soft-starter\/VFD current or torque multiplier.<\/p><p><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/62105\" target=\"_blank\" rel=\"noopener\">IEC61800-2:2021,Edition3<\/a> applies to adjustable-speed AC power-drive systems and provides criteria for selecting BDM\/CDM\/PDS performance and functional attributes. A VFD is a system selection,not a fixed1.2\u00d7 current entry.<\/p><p><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/67088\" target=\"_blank\" rel=\"noopener\">IEC60072-1:2022,Edition7<\/a> covers dimensions and output series for its stated industrial-machine scope. It does not prove that one hard-coded0.37\u2013315kW list is available or suitable for every technology,duty,speed,mounting or manufacturer.<\/p><\/section>\n<section class=\"ms-section\"><h2>What was corrected<\/h2><p>The former calculator ignored its load-type selector,rounded the torque conversion through9550 and multiplied the result by unsourced service-factor presets. It then chose from a partial hard-coded list;requirements above315kW silently returned315kW,creating a direct undersizing path.<\/p><p>Starting current was derived from hidden400V and PF0.85 assumptions while omitting motor efficiency,and fixed current\/torque multipliers were assigned to DOL,star-delta,soft starter and VFD without machine or system evidence. All automatic selection,starting estimates,standard-size tables and \u201calways oversize\u201d recommendations were removed.<\/p><\/section>\n<\/div>\n<script>(function(){'use strict';function $(id){return document.getElementById(id)}function num(s){s=String(s).trim();if(!s||s.includes('.')&&s.includes(',')||!\/^[+-]?(?:\\d+(?:[.,]\\d*)?|[.,]\\d+)(?:[eE][+-]?\\d+)?$\/.test(s))return NaN;var n=Number(s.replace(',','.'));return Number.isFinite(n)&&Math.abs(n)<=1e100?n:NaN}function fmt(n){if(n===0)return'0';var a=Math.abs(n);return a>=1e12||a<1e-8?n.toExponential(9):Number(n.toPrecision(12)).toLocaleString('en-US',{maximumFractionDigits:20})}function clear(){['ms-r-omega','ms-r-power','ms-r-torque','ms-r-required','ms-r-required-torque','ms-r-candidate-torque','ms-r-margin','ms-r-util','ms-r-candidate','ms-summary'].forEach(function(id){$(id).textContent='\u2014'});$('ms-results').hidden=true;$('ms-results').dataset.json=''}function fail(m){clear();$('ms-error').textContent=m}function sync(){var mode=$('ms-mode').value;$('ms-value-help').textContent=mode==='shaft-power'?'Enter mechanical shaft power in kW.':mode==='shaft-torque'?'Enter mechanical shaft torque in N\u00b7m.':'Select a quantity.'}function calc(){sync();var basis=$('ms-basis').value,mode=$('ms-mode').value,valueR=$('ms-value').value,speedR=$('ms-speed').value,factorR=$('ms-factor').value,cpR=$('ms-candidate-power').value.trim(),csR=$('ms-candidate-speed').value.trim(),source=$('ms-source').value.trim(),started=basis||mode||valueR.trim()||speedR.trim()||factorR.trim()||cpR||csR||source;if(!started){$('ms-error').textContent='';clear();return}if(basis!=='single-steady-motor-shaft-point'||!['shaft-power','shaft-torque'].includes(mode)||!source){fail('Select the controlled shaft-point basis and quantity,and document the load,multiplier and candidate sources.');return}if((cpR==='')!==(csR==='')){fail('Candidate rated output and candidate rated speed must be provided together or both left blank.');return}var value=num(valueR),speed=num(speedR),factor=num(factorR),candidatePower=cpR===''?null:num(cpR),candidateSpeed=csR===''?null:num(csR);if(![value,speed,factor].every(Number.isFinite)||candidatePower!==null&&(!Number.isFinite(candidatePower)||!Number.isFinite(candidateSpeed))){fail('Enter finite complete numbers;decimal point or decimal comma is accepted.');return}if(!(value>0&&speed>0&&factor>=1&&(candidatePower===null||candidatePower>0&&candidateSpeed>0))){fail('Known value and speed must be positive;documented multiplier must be at least1;optional candidate values must be positive.');return}var omega=2*Math.PI*speed\/60,power=mode==='shaft-power'?value:value*omega\/1000,torque=mode==='shaft-torque'?value:value*1000\/omega,requiredPower=power*factor,requiredTorque=torque*factor,candidateTorque=candidatePower===null?null:candidatePower*1000\/(2*Math.PI*candidateSpeed\/60),margin=candidatePower===null?null:candidatePower-requiredPower,util=candidatePower===null?null:requiredPower\/candidatePower*100;if(![omega,power,torque,requiredPower,requiredTorque].every(Number.isFinite)||[candidateTorque,margin,util].some(function(x){return x!==null&&!Number.isFinite(x)})){fail('The result exceeds the supported numerical range.');return}$('ms-error').textContent='';$('ms-r-omega').textContent=fmt(omega)+' rad\/s';$('ms-r-power').textContent=fmt(power)+' kW';$('ms-r-torque').textContent=fmt(torque)+' N\u00b7m';$('ms-r-required').textContent=fmt(requiredPower)+' kW';$('ms-r-required-torque').textContent=fmt(requiredTorque)+' N\u00b7m';if(candidatePower===null){$('ms-r-candidate-torque').textContent='Not evaluated';$('ms-r-margin').textContent='Not evaluated';$('ms-r-util').textContent='Not evaluated';$('ms-r-candidate').textContent='No candidate entered'}else{$('ms-r-candidate-torque').textContent=fmt(candidateTorque)+' N\u00b7m';$('ms-r-margin').textContent=fmt(margin)+' kW';$('ms-r-util').textContent=fmt(util)+' %';$('ms-r-candidate').textContent=fmt(candidatePower)+' kW at '+fmt(candidateSpeed)+' r\/min'}$('ms-summary').textContent='Single-point arithmetic only;no motor,starter,VFD or protection selection.';$('ms-results').dataset.json=JSON.stringify({basis:basis,known_quantity:mode,known_value:value,shaft_speed_rpm:speed,documented_capacity_multiplier:factor,angular_speed_rad_s:omega,shaft_load_power_kw:power,shaft_load_torque_nm:torque,documented_required_output_kw:requiredPower,documented_required_torque_at_load_speed_nm:requiredTorque,candidate_rated_output_kw:candidatePower,candidate_rated_speed_rpm:candidateSpeed,candidate_rated_torque_nm:candidateTorque,candidate_capacity_margin_kw:margin,candidate_utilization_percent:util});$('ms-results').hidden=false}$('ms-form').addEventListener('input',calc);$('ms-form').addEventListener('change',calc);sync();clear()})();<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Gratis motorst\u00f8rrelsesberegner. Indtast belastningstype, moment\/effekt, hastighed, driftscyklus og f\u00e5 den anbefalede motorst\u00f8rrelse fra standard IEC-omr\u00e5det 0,37-315 kW med estimater for startstr\u00f8m og moment.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100160","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/da\/wp-json\/wp\/v2\/calculator\/100160","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/da\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/da\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":2,"href":"https:\/\/vibromera.eu\/da\/wp-json\/wp\/v2\/calculator\/100160\/revisions"}],"predecessor-version":[{"id":102496,"href":"https:\/\/vibromera.eu\/da\/wp-json\/wp\/v2\/calculator\/100160\/revisions\/102496"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/da\/wp-json\/wp\/v2\/media?parent=100160"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/da\/wp-json\/wp\/v2\/categories?post=100160"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/da\/wp-json\/wp\/v2\/tags?post=100160"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}