Free Converters & Engineering Calculators

31 instant tools for engineers, machinists and buyers — units, metal weights, threads, valve flow and pump hydraulics. All calculations run in your browser: fast, private, free.

Unit Converters

mm · cm · m · km · in · ft · yd · mi

g · kg · ton · oz · lb · stone

m² · ha · ft² · acre

L · m³ · gal · barrel · ft³

°C · °F · K · °R

km/h · mph · m/s · knot · SFM

MPa · bar · psi · kgf/cm² · atm

N·m · kgf·m · lbf·ft

N · kN · kgf · lbf · tf

J · kJ · cal · kWh · BTU

W · kW · hp · PS · BTU/h

m³/h · L/min · GPM · bbl/d

ms · s · min · h · day · year

° · rad · gon · arcmin

bit · B · KB · MB · GB · TB

Metal & Weight

Metal Weight Calculator

6 shapes × 12 materials

Steel Plate Weight

per plate & per m²

OD × wall × length

Round Bar Weight

D²/162 steel formula

Square Tube Weight

SHS hollow sections

across-flats hex stock

Metal Density Chart

25+ alloys, g/cm³ · lb/in³

Threads & Fasteners

Tap Drill Calculator

metric + UNC/UNF chart

Metric Thread Chart

M1.6–M64 full dimensions

UNC / UNF Chart

unified inch threads

Bolt Torque Calculator

8.8 / 10.9 / 12.9 / A2-70

Three-Wire Measurement

M value & best wire size

Fluid & Pump

Cv / Kv Converter

valve flow coefficient

Valve Kv Sizing

size valves from duty flow

Pump Head Calculator

TDH + hydraulic power

NPSH Calculator

cavitation risk check

Pipe Pressure Drop

Darcy-Weisbach Δp

Reynolds Number

laminar / turbulent + f

Joukowsky surge ΔP

Pump Specific Speed

Nq / Ns impeller type

Machining

RPM ↔ Cutting Speed

Vc · SFM · RPM

roughness conversion table

Most Popular Conversions

Conversion	Formula	Example
1 meter to mm	1 m = 1000 mm	2.5 m = 2500 mm
1 inch to mm	1 in = 25.4 mm	2 in = 50.8 mm
1 kg to lb	1 kg = 2.20462 lb	10 kg = 22.046 lb
1 MPa to psi	1 MPa = 145.038 psi	5 MPa = 725.19 psi
1 bar to MPa	1 bar = 0.1 MPa	16 bar = 1.6 MPa
1 N·m to lbf·ft	1 N·m = 0.73756 lbf·ft	50 N·m = 36.88 lbf·ft
Kv to Cv	Cv = 1.156 × Kv	Kv 25 = Cv 28.9