Common Weight Conversions Reference

Here are the weight conversions you actually need every day: water, body weight, baby weight, gym plates, luggage, and a few others. Knowing the conversion factor (1 kg = 2.2 lb) is one thing; having reference points memorized is what makes you fluent.

Body weight by age and sex

Group	Kg	Lb
Newborn (average)	3.4	7 lb 8 oz
Toddler (age 2)	12	26 lb
Child (age 6)	21	46 lb
Pre-teen (age 10)	32	71 lb
Teenager (age 15)	55	121 lb
Adult woman (avg US)	78	171 lb
Adult man (avg US)	90	199 lb
Adult woman (avg UK)	71	157 lb
Adult man (avg UK)	84	185 lb

Common household and travel weights

Item	Kg	Lb
Carry-on suitcase	5-10	11-22
Checked baggage (economy limit)	23	50
Checked baggage (premium limit)	32	70
Standard laptop with charger	2-3	4-7
Bag of rice (small)	1	2.2
Bag of rice (large)	5-10	11-22
Gallon of water (US)	3.8	8.3
Gallon of water (UK)	4.5	10
Bag of cement	25	55
Car battery	15-22	33-49

Gym weight plates

Olympic standard plates come in dual-labeled sizes. The kg plates round to 2.5, 5, 10, 15, 20, 25 kg. The corresponding pound plates are 5, 10, 25, 35, 45, 55 lb (note these are not exact conversions; gyms use rounded sizes for convenience). An empty Olympic barbell weighs 20 kg in metric gyms and 45 lb in US gyms.

Plate	Kg	Lb
Tiny	2.5	5
Small	5	10
Medium	10	25
Large	15	35
Standard	20	45
Big	25	55
Olympic barbell (empty)	20	45

Babies: weight by age

Healthy growth ranges based on WHO and CDC charts:

Age	Average kg	Average lb
Newborn	3.4	7 lb 8 oz
1 month	4.5	9 lb 14 oz
3 months	6.4	14 lb 2 oz
6 months	7.9	17 lb 7 oz
9 months	9.0	19 lb 13 oz
1 year	10.2	22 lb 8 oz
2 years	12.5	27 lb 9 oz

Why these conversions matter

Body weight: doctors and recipes for medication dose use kg; bathroom scales in the US use lb. Conversion fluency lets you understand a doctor's notes regardless of system. Baby weight: pediatric growth charts use kg internationally but lb-and-oz in the US, and converting between them is part of normal child-rearing. Gym plates: international gym chains and home gym buying often need kg-to-lb fluency. Airline luggage: international flights enforce kg limits but many US travelers think in lb.

The math itself is easy: kg × 2.2 = lb, lb / 2.2 = kg. The fluency comes from having reference points memorized so you can sanity-check quickly. Knowing 70 kg ≈ 154 lb and 90 kg ≈ 200 lb covers most adult body-weight conversions; knowing 1 gallon of water = 8.3 lb (US) or 10 lb (UK) covers most liquid contexts.

Frequently asked questions

How heavy is a gallon of water?

A US gallon of water weighs 3.785 kg (8.345 lb) at 4°C. A UK (imperial) gallon weighs 4.546 kg (10.02 lb). For most everyday math, treat a US gallon of water as 8.3 pounds and a UK gallon as 10 pounds. The famous rhyme "a pint's a pound the world around" is roughly true for US pints (about 1.04 lb) but less accurate for UK pints (1.25 lb).

How much does a baby weigh on average?

Average newborn birth weight in developed countries is about 3.4 kg (7 lb 8 oz). Healthy range: 2.5-4.5 kg (5 lb 8 oz to 9 lb 15 oz). Underweight: below 2.5 kg (5 lb 8 oz). Macrosomia: above 4.5 kg (9 lb 15 oz). Premature babies can weigh much less; the survivable range with modern care starts around 500 g (1 lb 2 oz).

How much does an average adult weigh?

Global average adult weight is about 62 kg (137 lb). US average for men is 90 kg (199 lb); for women 78 kg (171 lb). UK average for men is 84 kg (185 lb); for women 71 kg (157 lb). India average for men is 65 kg; for women 55 kg. Variations are partly genetic, partly nutritional, partly cultural.

What does a typical gym weight plate weigh?

Olympic plates (with 50 mm center hole) come in standard sizes: 25 kg / 55 lb, 20 kg / 45 lb, 15 kg / 35 lb, 10 kg / 25 lb, 5 kg / 10 lb, 2.5 kg / 5 lb. In the US, weights are labeled in pounds (5, 10, 25, 35, 45 lb). In metric gyms, plates are labeled in kg (2.5, 5, 10, 15, 20, 25 kg). An empty Olympic barbell weighs 20 kg / 45 lb.

What is the airline checked baggage limit?

Standard economy checked baggage is 23 kg (50 lb) on most international flights. Premium cabins often allow 32 kg (70 lb). Excess weight fees kick in above the limit at most carriers and can be steep (often $50-200 per overweight bag). Carry-on bags are typically 7-10 kg (15-22 lb), but enforcement varies by airline.

How much does a typical adult bicycle weigh?

Entry-level road bikes: 10-12 kg (22-26 lb). Performance road bikes: 7-9 kg (15-20 lb). High-end carbon road bikes: 6-7 kg (13-15 lb). Mountain bikes: 11-14 kg (24-31 lb). Electric bikes: 18-25 kg (40-55 lb) because of the battery and motor.

How much does a car battery weigh?

Standard 12V lead-acid car battery: 12-22 kg (26-49 lb). Heavy-duty batteries for trucks: 22-30 kg (49-66 lb). Electric vehicle traction batteries: 250-700 kg (550-1,540 lb) for the entire pack. The lead-acid weight is the reason proper lifting technique matters when replacing one.

How heavy is a person carrying their luggage?

Add typical luggage weights to body weight for elevator and weight-limit purposes. Carry-on suitcase: 5-10 kg (11-22 lb). Large checked suitcase: 15-23 kg (33-50 lb). Backpack with laptop: 2-5 kg (4-11 lb). A 75 kg adult with full luggage might total 95-105 kg (210-230 lb).

Common Weight Conversions: Water, Body Weight, Baby Weight