📖 11 min read

Understanding Kilograms and Pounds

In the United Kingdom, we live with a fascinating mix of measurement systems. While the metric kilogram is the official unit of mass, many Brits still think about their body weight in stone and pounds, weigh their babies in pounds and ounces, and compare weights using either system depending on the context.

The kilogram (kg) is the base unit of mass in the International System of Units (SI), defined since 2019 by the Planck constant. The pound (lb) is part of the imperial system, with its name derived from the Latin "libra" - which is why we abbreviate it as "lb".

Try Our Free KG to LBS Converter

Get instant results with our KG to LBS Converter. Also check our KG to Stone Calculator and BMI Calculator.

The Conversion Formulas

Kilograms to Pounds: Pounds = Kilograms × 2.20462
Pounds to Kilograms: Kilograms = Pounds × 0.45359

For everyday calculations, you can use simplified versions: multiply kg by 2.2 to get pounds, or divide pounds by 2.2 to get kilograms. This gives results accurate to within about 1%.

Quick Reference Conversion Table

Kilograms (kg) Pounds (lbs) Stone & Pounds
12.20st 2lb
511.00st 11lb
1022.01st 8lb
2044.13st 2lb
3066.14st 10lb
4088.26st 4lb
50110.27st 12lb
60132.39st 6lb
70154.311st 0lb
80176.412st 8lb
90198.414st 2lb
100220.515st 10lb
110242.517st 4lb
120264.618st 12lb

Body Weight Conversions

Body weight is where most people in the UK need to convert between kg and lbs. Whether you're tracking your weight on a metric scale or comparing with American fitness guidelines, these conversions are essential.

Common Body Weights

Weight (kg) Weight (lbs) UK Stone Common Reference
501107st 12lbLighter adult
571269st 0lbAverage woman (UK)
63.514010st 0lb10 stone exactly
7015411st 0lbAverage build
7616812st 0lb12 stone exactly
8318313st 1lbAverage man (UK)
8919614st 0lb14 stone exactly
10022015st 10lbHeavy build

NHS Weight Guidelines

The NHS uses Body Mass Index (BMI) calculated with weight in kilograms and height in metres:

  • Underweight: BMI below 18.5
  • Healthy weight: BMI 18.5 to 24.9
  • Overweight: BMI 25 to 29.9
  • Obese: BMI 30 or above

Baby Weight Conversions

In the UK, baby weights are often discussed in pounds and ounces, while medical records typically use kilograms. Here are common birth weight conversions:

Kilograms Pounds & Ounces Notes
2.55lb 8ozLow birth weight threshold
3.06lb 10ozSmaller newborn
3.47lb 8ozAverage UK birth weight
3.67lb 15ozHealthy newborn
4.08lb 13ozLarger newborn
4.59lb 15ozLarge birth weight

Fitness and Gym Applications

UK gyms often have equipment marked in both kg and lbs. Olympic and standard weight plates commonly come in these sizes:

Olympic Weight Plates

Plate (kg) Plate (lbs) Colour Code
1.252.76No standard
2.55.51No standard
511.02White
1022.05Green
1533.07Yellow
2044.09Blue
2555.12Red
Gym Equipment Note: American programmes often prescribe weights in pounds. When following US workout plans in a UK gym, remember to convert: 135 lbs ≈ 61 kg, 225 lbs ≈ 102 kg, 315 lbs ≈ 143 kg.

Luggage and Travel

Airlines typically specify baggage allowances in kilograms, though some American carriers use pounds:

Allowance (kg) Allowance (lbs) Common Usage
715.4Economy cabin bag
1022.0Hand luggage limit
1533.1Budget airline checked bag
2044.1Standard economy checked
2350.7Standard international
3270.5Business class / Premium

Worked Examples

Example 1: Body Weight Conversion

Your scales show 75 kg. What is this in stone and pounds?

Step 1: Convert to pounds: 75 × 2.20462 = 165.35 lbs

Step 2: Divide by 14 for stone: 165.35 ÷ 14 = 11.81 stone

Step 3: Get the remainder: 0.81 × 14 = 11.3 lbs

Answer: 75 kg = 11 stone 11 pounds

Example 2: Gym Weight Conversion

A workout plan says to squat 185 lbs. How many kg plates do you need?

Step 1: Convert to kg: 185 ÷ 2.20462 = 83.9 kg

Step 2: Subtract barbell weight (Olympic bar = 20 kg): 83.9 - 20 = 63.9 kg

Step 3: Divide by 2 for each side: 63.9 ÷ 2 = 32 kg per side

Answer: Load each side with 20 kg + 10 kg + 2.5 kg plates (or closest available)

Example 3: Baby Weight Update

Your baby weighed 3.2 kg at birth. The health visitor notes they've gained 1.8 kg. What do they weigh now in pounds?

Step 1: Add the weights: 3.2 + 1.8 = 5.0 kg

Step 2: Convert to pounds: 5.0 × 2.20462 = 11.02 lbs

Answer: Your baby now weighs 11 lbs (or 11 lbs 0 oz)

Mental Maths Shortcuts

These tricks help you estimate conversions without a calculator:

Frequently Asked Questions

How many pounds are in a kilogram?

One kilogram equals approximately 2.20462 pounds. For quick mental maths, you can use 2.2 lbs per kg as a good approximation.

How do I convert kg to lbs?

To convert kilograms to pounds, multiply the weight in kilograms by 2.20462. For example, 70 kg × 2.20462 = 154.32 lbs.

Is 1 kg the same as 2 lbs?

No, 1 kilogram is slightly heavier than 2 pounds. One kilogram equals approximately 2.2 pounds, so 1 kg is about 10% heavier than 2 lbs.

Why does the UK use both kilograms and pounds?

The UK officially adopted the metric system but retains imperial measurements in everyday life. People often weigh themselves in stone and pounds, while food packaging uses grams and kilograms.

How much is 10 stone in kilograms?

10 stone equals 140 pounds, which converts to approximately 63.5 kilograms.

Need quick weight conversions?

Try Our Free Online Calculators →

Weight Measurement in the UK: A Unique Situation

The United Kingdom occupies a unique position globally in its use of weight measurements, routinely switching between metric and imperial systems in everyday life. While the UK officially adopted the metric system for trade and commerce under the Weights and Measures Act 1985, the imperial system remains deeply embedded in daily culture. NHS records and GP surgeries record patient weights in kilograms, yet most British people express their personal weight in stone and pounds. Supermarkets price items per kilogram as required by law, but recipes and cookbooks frequently reference ounces and pounds.

This dual-system approach has historical roots. The UK began its metrication process in 1965 but never completed a full transition. Road signs remain in miles, pubs serve beer in pints, and body weight is colloquially discussed in stone. A 2022 YouGov survey found that 65% of UK adults preferred to give their weight in stone and pounds, while only 28% used kilograms. For fitness and health contexts, understanding both systems is essential. UK gym equipment typically displays both units, and popular UK health apps such as the NHS BMI Calculator accept input in either kilograms or stone and pounds.

Frequently Asked Questions About Kg to Lbs Conversion

Why do UK doctors use kilograms but patients think in stone?
The NHS adopted the metric system for all medical records because kilograms provide more precise measurements for calculating drug dosages, BMI scores, and clinical assessments. Medication doses are universally calculated per kilogram of body weight, making metric units essential for patient safety. However, most UK patients grew up using stone and pounds in daily life, so they naturally think and communicate in imperial units. GP surgeries and hospitals typically accommodate both by converting between systems, and digital health records automatically store weights in kilograms regardless of how the measurement was initially taken.
What is the difference between a UK pound and a US pound?
There is no difference. The avoirdupois pound used in the UK and the US are identical, both equalling exactly 0.45359237 kilograms. This international standard was agreed in 1959 by English-speaking nations. The only historical distinction was the troy pound (used for precious metals), which equals approximately 0.373 kg and is still used in the UK gold and silver trade. When converting kg to lbs for everyday purposes such as body weight, cooking, or shipping, the standard avoirdupois pound is always used in both countries.
How do I convert between stone, pounds, and kilograms?
One stone equals 14 pounds or approximately 6.35 kilograms. To convert from stone and pounds to kilograms, first convert everything to pounds (multiply stone by 14 and add any remaining pounds), then divide by 2.20462. For example, 11 stone 4 pounds equals 158 pounds, which converts to 71.67 kilograms. To go the other way, multiply kilograms by 2.20462 to get pounds, then divide by 14 to find the stone value with the remainder as pounds. For example, 80 kg equals 176.37 pounds, which is 12 stone 8.4 pounds.

Did You Know? Kilograms and Pounds in UK Life

The kilogram-to-pound conversion is uniquely important in the United Kingdom because British people use both systems regularly, often within the same conversation. Understanding when each unit is typically used helps make sense of the UK's distinctive measurement culture.

Body weight conventions. Most UK adults know their weight in stone and pounds rather than kilograms, even though NHS records use metric. The stone (14 pounds or 6.35 kg) is a unit almost exclusive to the UK and Ireland. When someone says they weigh 11 stone, they mean 154 pounds or approximately 70 kilograms. However, gym scales, medical records, and fitness apps default to kilograms, creating a constant need for conversion. The average UK adult male weighs approximately 84 kg (13 stone 3 lbs or 185 lbs), while the average UK adult female weighs approximately 72 kg (11 stone 5 lbs or 159 lbs), according to NHS Health Survey for England data.

Food shopping conversions. UK supermarkets price fresh produce per kilogram, as required by the Weights and Measures (Packaged Goods) Regulations. However, many shoppers, particularly older generations, still think in pounds when judging quantities. A pound of mince (454g) makes approximately four burgers. A kilogram of chicken breasts contains roughly four to five portions. Butchers and market traders in the UK may still accept orders in pounds, but their scales display kilograms, so understanding both systems helps you shop confidently in any setting.

Luggage allowances. UK airline luggage allowances are always stated in kilograms. Ryanair allows 10 kg for cabin bags and 20 kg for checked luggage. British Airways allows 23 kg per checked bag in economy. If you are accustomed to thinking in pounds, knowing that 23 kg equals about 50.7 pounds, or that 10 kg is approximately 22 pounds, helps you pack without exceeding limits and incurring excess baggage charges that can cost 10 to 15 pounds per kilogram at the airport.

Why does the UK use stone for body weight?
The stone has been used as a unit of weight in the British Isles since at least the 14th century, when it was formalised at 14 pounds by royal decree. Its persistence for body weight is a matter of cultural habit rather than legal requirement. The stone was officially removed from the list of legal units of measurement in the UK in 1985, but it remains universally understood and used in everyday conversation. No other country uses stone regularly, which often surprises UK travellers who discover that even Ireland, where stone is also used, is gradually shifting to kilograms for health records. The NHS records weight in kilograms, but most UK residents still describe their weight in stone to friends and family.
How do I convert between stone, pounds, and kilograms?
To convert stone to kilograms, multiply by 6.35. To convert stone to pounds, multiply by 14. To convert kilograms to stone and pounds, divide by 6.35 to get stone, then multiply the decimal remainder by 14 to get the remaining pounds. For example, 80 kg divided by 6.35 equals 12.6 stone, and 0.6 multiplied by 14 equals 8.4 pounds, so 80 kg is 12 stone 8 pounds (rounded). For quick mental conversion from kg to lbs, multiply by 2.2. From lbs to kg, multiply by 0.45 or divide by 2.2. These approximations are accurate enough for everyday use.
Are UK and US pounds the same weight?
Yes, the avoirdupois pound used in the UK and the US is identical, defined as exactly 0.45359237 kilograms. This was standardised in 1959 when the UK, US, Canada, Australia, New Zealand, and South Africa agreed on a single international definition. However, where confusion arises is with fluid measurements: the UK imperial gallon (4.546 litres) is larger than the US gallon (3.785 litres), and the UK pint (568 ml) is larger than the US pint (473 ml). So while a pound of sugar weighs the same in both countries, a pint of milk does not measure the same volume.
UK Calculator Financial Team

Our team of financial experts creates accurate, easy-to-use calculators and guides to help you make informed decisions about your money.

Dr. Sarah Chen, PhD

Dr. Sarah Chen, PhD

Research Scientist, Public Health

Sarah holds a PhD in Public Health from the University of Edinburgh and has published research on UK health metrics and obesity trends. She translates complex medical data into practical, accessible guidance for everyday readers.

Share this guide

Twitter Facebook LinkedIn WhatsApp Email

Last updated: February 2026 | Verified with latest UK rates