Motor Power and Torque Calculator
ANA›Life Services Authority›National Calculator Authority›Motor Power and Torque Calculator
.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }
Motor Power and Torque Calculator
Calculate mechanical power, torque, and rotational speed for electric motors using standard engineering formulas.
Calculate:
Power (given Torque & Speed) Torque (given Power & Speed) Speed (given Power & Torque)
Torque (T):
N·m ft·lb in·lb kN·m
Rotational Speed (n):
RPM RPS (rev/s) rad/s
Power (P):
W kW hp
Motor Efficiency (η): (optional, 1–100%)
Calculate
function motUpdateMode() { var mode = document.getElementById('mot-calc-mode').value; document.getElementById('mot-torque-group').style.display = (mode === 'power') ? 'block' : (mode === 'speed' ? 'block' : 'none'); document.getElementById('mot-speed-group').style.display = (mode === 'power') ? 'block' : (mode === 'torque' ? 'block' : 'none'); document.getElementById('mot-power-group').style.display = (mode === 'torque') ? 'block' : (mode === 'speed' ? 'block' : 'none');
// torque group: show for power and speed modes document.getElementById('mot-torque-group').style.display = (mode === 'torque') ? 'none' : 'block'; // power group: show for torque and speed modes document.getElementById('mot-power-group').style.display = (mode === 'power') ? 'none' : 'block'; // speed group: show for power and torque modes document.getElementById('mot-speed-group').style.display = (mode === 'speed') ? 'none' : 'block';
document.getElementById('mot-result').innerHTML = ''; }
function motToNm(val, unit) { if (unit === 'Nm') return val; if (unit === 'ftlb') return val * 1.35582; if (unit === 'inlb') return val * 0.112985; if (unit === 'kNm') return val * 1000; return val; }
function motToRads(val, unit) { if (unit === 'rpm') return val * Math.PI / 30; if (unit === 'rps') return val * 2 * Math.PI; if (unit === 'rads') return val; return val; }
function motToWatts(val, unit) { if (unit === 'W') return val; if (unit === 'kW') return val * 1000; if (unit === 'hp') return val * 745.69987; return val; }
function motFormatPower(W) { if (W >= 1e6) return (W/1e6).toFixed(4) + ' MW'; if (W >= 1000) return (W/1000).toFixed(4) + ' kW'; return W.toFixed(4) + ' W'; }
function motFormatTorque(Nm) { if (Nm >= 1000) return (Nm/1000).toFixed(4) + ' kN·m'; return Nm.toFixed(4) + ' N·m'; }
function motFormatSpeed(rads) { var rpm = rads * 30 / Math.PI; return rpm.toFixed(2) + ' RPM (' + rads.toFixed(4) + ' rad/s)'; }
function motCalc() { var res = document.getElementById('mot-result'); var mode = document.getElementById('mot-calc-mode').value; var effVal = parseFloat(document.getElementById('mot-efficiency').value);
if (isNaN(effVal) || effVal 100) { res.innerHTML = 'Efficiency must be between 1 and 100%.'; return; } var eta = effVal / 100;
if (mode === 'power') { var T_raw = parseFloat(document.getElementById('mot-torque').value); var n_raw = parseFloat(document.getElementById('mot-speed').value); var T_unit = document.getElementById('mot-torque-unit').value; var n_unit = document.getElementById('mot-speed-unit').value;
if (isNaN(T_raw) || T_raw Please enter a valid positive Torque value.'; return; } if (isNaN(n_raw) || n_raw Please enter a valid positive Speed value.'; return; }
var T_Nm = motToNm(T_raw, T_unit); var omega = motToRads(n_raw, n_unit); var P_mech = T_Nm * omega; var P_elec = P_mech / eta;
res.innerHTML = 'Results:' + 'ω (angular velocity) = ' + omega.toFixed(4) + ' rad/s' + 'Mechanical Power (Pmech) = ' + motFormatPower(P_mech) + '' + (eta elec) = ' + motFormatPower(P_elec) + ' (at η = ' + effVal + '%)' : '') + 'Torque = ' + motFormatTorque(T_Nm) + 'Speed = ' + motFormatSpeed(omega);
} else if (mode === 'torque') { var P_raw = parseFloat(document.getElementById('mot-power').value); var n_raw = parseFloat(document.getElementById('mot-speed').value); var P_unit = document.getElementById('mot-power-unit').value; var n_unit = document.getElementById('mot-speed-unit').value;
if (isNaN(P_raw) || P_raw Please enter a valid positive Power value.'; return; } if (isNaN(n_raw) || n_raw Please enter a valid positive Speed value.'; return; }
var P_W = motToWatts(P_raw, P_unit); var omega = motToRads(n_raw, n_unit); var P_mech = P_W * eta; var T_Nm = P_mech / omega;
res.innerHTML = 'Results:' + 'ω (angular velocity) = ' + omega.toFixed(4) + ' rad/s' + 'Torque (T) = ' + motFormatTorque(T_Nm) + '' + 'Torque = ' + (T_Nm * 0.737562).toFixed(4) + ' ft·lb' + 'Torque = ' + (T_Nm * 8.85075).toFixed(4) + ' in·lb' + (eta Please enter a valid positive Power value.'; return; } if (isNaN(T_raw) || T_raw Please enter a valid positive Torque value.'; return; }
var P_W = motToWatts(P_raw, P_unit); var T_Nm = motToNm(T_raw, T_unit); var P_mech = P_W * eta; var omega = P_mech / T_Nm; var rpm = omega * 30 / Math.PI;
res.innerHTML = 'Results:' + 'Speed (n) = ' + rpm.toFixed(2) + ' RPM' + 'ω = ' + omega.toFixed(4) + ' rad/s' + 'Speed = ' + (omega / (2 * Math.PI)).toFixed(4) + ' RPS' + (eta
#### Formulas Used
Mechanical Power: P = T × ω where ω = 2πn/60 (rad/s) when n is in RPM
Torque: T = P / ω
Rotational Speed: ω = P / T → n (RPM) = ω × 60 / (2π)
Efficiency: Pmech = Pelec × η η = mechanical output power / electrical input power
Unit Conversions: 1 ft·lb = 1.35582 N·m | 1 in·lb = 0.112985 N·m 1 hp = 745.69987 W | 1 kW = 1000 W
#### Assumptions & References
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