Free Engineering Tool
Mass & Weight Converter
Convert between all major mass and weight units instantly. Metric and imperial units shown simultaneously.
All Units
| Unit | = Kilograms | Notes |
|---|---|---|
| 1 mg | 0.000001 | Milligram |
| 1 grain | 0.00006479891 | Troy/Avoirdupois grain |
| 1 g | 0.001 | Gram |
| 1 oz | 0.028349523 | Avoirdupois ounce |
| 1 lb | 0.45359237 | Avoirdupois pound |
| 1 kg | 1 | SI base unit |
| 1 stone | 6.35029318 | 14 pounds |
| 1 short ton | 907.18474 | US ton (2000 lb) |
| 1 long ton | 1016.0469 | UK/Imperial ton (2240 lb) |
| 1 tonne | 1000 | Metric ton |
Common Engineering Mass Conversions
| From → To | Multiply by | Example |
|---|---|---|
| kg → lb | 2.20462 | 100 kg = 220.46 lb |
| lb → kg | 0.45359 | 100 lb = 45.36 kg |
| oz → g | 28.3495 | 1 oz = 28.35 g |
| g → oz | 0.03527 | 100 g = 3.53 oz |
| tonne → short ton | 1.10231 | 1 t = 1.102 short tons |
| short ton → tonne | 0.90718 | 1 ST = 0.907 t |
| stone → kg | 6.35029 | 10 stone = 63.5 kg |
Handy Memorization Tips
- 1 kg ≈ 2.2 lb (for quick estimates)
- 1 lb ≈ 454 g
- 1 ounce ≈ 28.35 g
- 1 stone = 14 lb = 6.35 kg (used in UK for body weight)
- 1 tonne = 1000 kg ≈ 2205 lb
- 1 short ton (US) = 2000 lb ≈ 907 kg
- 1 long ton (UK) = 2240 lb ≈ 1016 kg
- 1 grain ≈ 64.8 mg (used in ballistics and pharmacy)
Mass vs Weight
In everyday use, “weight” and “mass” are used interchangeably, but they differ:
- Mass (kg, lb-mass) is the amount of matter — constant everywhere
- Weight (N, lbf) is the gravitational force — varies with location
- On Earth’s surface: Weight (N) = Mass (kg) × 9.81 m/s²
- A 100 kg mass weighs 981 N on Earth but only 163 N on the Moon
Application-Specific Units
- Balancing: Unbalance measured in g·mm (grams × millimeters) or oz·in (ounces × inches)
- Pharmacy: Grains (1 gr = 64.8 mg), drams, scruples
- Precious metals: Troy ounce (31.103 g) ≠ Avoirdupois ounce (28.350 g)
- Gemstones: Carat (1 ct = 0.2 g)
Useful mass references for sanity-checking calculations and estimates.
| Object | Mass (kg) | Mass (lb) |
|---|---|---|
| M10 hex bolt (50mm) | 0.035 | 0.077 |
| Standard brick | 3.1 | 6.8 |
| Car wheel (steel, 16″) | 9 | 20 |
| Electric motor (1.5 kW, 4-pole) | 15 | 33 |
| Electric motor (7.5 kW, 4-pole) | 42 | 93 |
| Pallet of cement (40 bags) | 1000 | 2205 |
| Small car | 1200 | 2646 |
| Empty 20ft shipping container | 2300 | 5071 |
| Loaded 20ft shipping container (max) | 28200 | 62170 |
Steel Weight Quick Estimates
| Shape | Formula (kg) | Example |
|---|---|---|
| Steel plate (mm, m²) | thickness × area × 7.85 | 10mm × 1m² = 78.5 kg |
| Round bar (mm, m) | d² × length × 0.00617 | ø50 × 1m = 15.4 kg |
| Pipe (mm, m) | (OD² − ID²) × L × 0.00617 | ø114.3×3.6mm × 1m = 9.8 kg |
Professional engineering calculators and measurement instruments.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
