How do I calculate torque from horsepower?

Torque (Nm) = Power (W) / Angular Velocity (rad/s), or Torque (lb·ft) = (HP × 5252) / RPM. For example, a 10 HP motor at 1750 RPM produces: T = (10 × 5252) / 1750 = 30 lb·ft = 40.7 Nm.

How do I size an HVAC duct using the equal friction method?

The equal friction method maintains constant pressure loss per unit length (typically 0.1 in.w.g./100 ft or 0.8 Pa/m). Duct size is found from: Q = A × V, where Q is airflow (CFM or m³/h) and V is velocity (typically 1,000–2,500 FPM for supply air). Use our HVAC Duct Sizing Calculator for instant results per ASHRAE standards.

What is the formula for pipe flow velocity?

Pipe flow velocity V = Q / A, where Q is volumetric flow rate (m³/s or GPM) and A is pipe cross-sectional area (m² or ft²). For a standard pipe: V = 4Q / (π × D²). Reynolds number Re = ρVD/μ determines flow regime (laminar 4000).

How do you calculate bearing L10 life?

Bearing L10 life = (C/P)^p × (10⁶/60n) hours, where C is dynamic load rating (kN), P is equivalent dynamic bearing load (kN), p is 3 for ball bearings or 10/3 for roller bearings, and n is rotational speed (RPM). This gives the life at which 90% of bearings will survive.

How do I calculate heat load for a room (HVAC)?

Heat load Q = U × A × ΔT for conduction through walls, plus solar gain, occupancy (75W sensible per person), lighting (10 W/m²) and equipment loads. Per ASHRAE, total cooling load = sensible + latent loads. Use our Heat Load Calculator for full Manual J-style calculations.

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Mechanical Engineering Calculator

Precision mechanical engineering calculators — Torque, Gear Ratio, Belt Drive, Spring Constant, Bearing Life, Shaft Power, Stress & Strain analysis with professional PDF reports.

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About Our Mechanical Engineering Calculators

Mechanical engineering calculators on AI Calculator solve the everyday math behind moving parts, structural members, fluid flow, heat transfer, and rotating equipment. Whether you are sizing a pump for a chilled-water loop, choosing a gear ratio for a conveyor drive, calculating the deflection of a simply supported beam, or estimating the bearing life of a rotating shaft, the goal of this suite is to give you a verified result in seconds, with the formula and the input assumptions visible right next to the answer. Every calculator on this page is built around the equations published in widely used references — the ASME Boiler & Pressure Vessel Code, the Crane Technical Paper No. 410 for fluid flow, Shigley's Mechanical Engineering Design for shaft and gear work, and Cameron's Hydraulic Data for pump head loss. Inputs are unit-aware, results are dimensioned, and every page can export a branded PDF report you can attach to a calculation file or a design review submittal.

Calculators in This Mechanical Suite

HVAC Calculator — duct sizing, cooling load (Manual J style), heating load, refrigeration tonnage, and chilled-water flow rate (gpm) from a heat-load input.
Pipe Sizing Calculator — Hazen-Williams and Darcy-Weisbach friction loss for water, with diameter recommendations for a target velocity (typically 1.5–2.4 m/s for chilled water).
Pump Head Calculator — total dynamic head from static lift, friction head, and pressure head; useful for centrifugal pump selection against a manufacturer curve.
Heat Exchanger Calculator — LMTD method and effectiveness-NTU for shell-and-tube and plate heat exchangers; outputs required surface area for a duty.
Reynolds Number Calculator — distinguishes laminar (Re < 2300), transitional, and turbulent (Re > 4000) flow regimes for any fluid in a circular pipe.
Torque Calculator — relates torque, power, and rotational speed (P = T·ω); also calculates motor full-load torque from kW and rpm.
Gear Ratio Calculator — output speed and torque multiplication for spur, helical, and bevel gear trains.

Common Formulas Used Across This Suite

The Reynolds number calculator implements Re = ρvD / μ, where ρ is fluid density (kg/m³), v is mean velocity (m/s), D is pipe inside diameter (m), and μ is dynamic viscosity (Pa·s). For water at 20 °C, μ ≈ 1.002 × 10⁻³ Pa·s. The pump head calculator uses the standard Bernoulli energy equation: H = (P₂ − P₁)/(ρg) + (z₂ − z₁) + (v₂² − v₁²)/(2g) + h_f, where h_f aggregates friction and minor losses. The torque calculator applies T (N·m) = 9550 × P(kW) / N(rpm), the workhorse equation when sizing a motor against a known driven-load torque. The HVAC calculator uses sensible cooling load Q = 1.08 × CFM × ΔT in IP units, or Q = 1.21 × L/s × ΔT in SI, with humidity-driven latent loads added separately.

When to Use Each Calculator

Pipe sizing and pump head go together: first run the pipe sizing calculator to lock in a diameter that keeps velocity in the 1.5–2.4 m/s sweet spot (lower causes silting, higher causes erosion and noise), then feed that diameter and the system layout into the pump head calculator to pick a centrifugal pump whose curve passes above your duty point at the system curve intersection. The Reynolds number calculator is your sanity check — if Re is below 2300 you are in the laminar regime and the friction factor follows f = 64/Re; above 4000 you need the Colebrook-White equation or the Moody chart. For HVAC work, start with the cooling load calculator to set the chilled-water tonnage, then size piping and pumping to deliver that tonnage at design ΔT (typically 6 °C / 11 °F).

Frequently Asked Questions

Which standards do the mechanical calculators reference?
Where applicable: ASME B31.1 (Power Piping), ASME B31.3 (Process Piping), ASHRAE Fundamentals (HVAC loads), Cameron's Hydraulic Data, and AGMA standards (gearing). Each calculator page lists its primary reference at the bottom of the page.

Are the results good enough for professional submittals?
The math is correct and the equations are the same ones in the source standards, but a calculator output is not a substitute for a stamped engineering review. Use these tools for first-pass sizing, design reviews, and learning. For construction documents, a licensed Professional Engineer should verify the assumptions and sign off.

Do the calculators support imperial (US) and metric (SI) units?
Yes — every input field has a unit selector. You can mix systems within one calculation (for example, enter pipe diameter in inches and flow rate in L/min); the engine converts internally to SI before computing.

Can I export results as a PDF?
Yes — every calculator has a PDF Report button that exports a branded one-page report including the inputs, the formula, intermediate steps where useful, and the final result with units. Useful as backup in a calculation file.

Related calculator categories: Electrical engineering · Civil & structural · Chemical & process · Physics · Engineering formulas reference