Weight Converter
Convert between pounds, kilograms, ounces, grams, and stone. Perfect for cooking, fitness tracking, shipping, and international travel.
Common Weight References
Related Calculators
About This Calculator
Whether you're trying to figure out your weight for a gym in Europe, converting a recipe from a British cookbook, or shipping a package internationally, weight conversions come up more often than you'd think. The most common question? "How many pounds are in a kilogram?" (It's 2.205, by the way—but who can remember that?) This Weight Converter instantly converts between pounds, kilograms, ounces, grams, and stone, so you never have to do the mental math again. Here's the thing: the metric system (kilograms, grams) is used by literally every country except the US, Myanmar, and Liberia. So if you're traveling, shopping online from international stores, or following a fitness plan from a European trainer, you'll run into metric weights constantly. And if you're from the UK, you've got the added fun of "stone"—a unit Americans find completely baffling. This calculator handles it all, whether you need to know how much 70 kg is in pounds (154 lbs—a healthy weight for many adults) or how many grams are in an ounce for your sourdough recipe (28.35g, for the curious bakers out there).
How to Use the Weight Converter
- 1Enter the weight value you want to convert in the input field.
- 2Select your starting unit (what you have) from the "From" column—kg, lbs, oz, grams, stone, or mg.
- 3Select your target unit (what you need) from the "To" column.
- 4Use the quick preset buttons for common conversions like kg→lbs or oz→g.
- 5Click the swap button (↔) to quickly reverse your conversion.
- 6View all equivalent weights at once in the results panel.
- 7Copy your result to paste into other apps, recipes, or shipping forms.
Formula
Target Weight = Source Weight × (Source Unit in Grams ÷ Target Unit in Grams)Weight conversion works by using a base unit (grams) as the common denominator. Every unit has a fixed relationship to grams: 1 kg = 1,000 g, 1 lb = 453.592 g, 1 oz = 28.3495 g, 1 stone = 6,350.29 g. To convert, we first change your input to grams, then divide by the target unit's gram equivalent. For example, to convert 10 pounds to kilograms: 10 lbs × 453.592 g/lb = 4,535.92 g ÷ 1,000 g/kg = 4.536 kg. The calculator does this math instantly for all units simultaneously.
Kilograms to Pounds: The Conversion Everyone Needs
Let's be honest—kg to lbs is probably why you're here. It's the most common weight conversion worldwide, especially for:
Body Weight:
- Gym machines in Europe display kg
- Medical records vary by country
- Fitness apps may default to metric
Quick Mental Math Trick: To roughly convert kg to lbs in your head: double it and add 10%
- 70 kg → 140 + 14 = ~154 lbs (actual: 154.3)
- 80 kg → 160 + 16 = ~176 lbs (actual: 176.4)
- 60 kg → 120 + 12 = ~132 lbs (actual: 132.3)
Common Body Weight Conversions:
| Kilograms | Pounds | Stone + Pounds |
|---|---|---|
| 50 kg | 110.2 lbs | 7 st 12 lbs |
| 60 kg | 132.3 lbs | 9 st 6 lbs |
| 70 kg | 154.3 lbs | 11 st 0 lbs |
| 80 kg | 176.4 lbs | 12 st 8 lbs |
| 90 kg | 198.4 lbs | 14 st 2 lbs |
| 100 kg | 220.5 lbs | 15 st 10 lbs |
Why the US Uses Pounds: The US adopted the British Imperial system before the metric system was standardized internationally. By the time the rest of the world switched to metric (1960s-70s), American infrastructure was too entrenched in imperial units. There have been multiple failed attempts to "go metric" in the US—the most recent serious effort was in the 1970s.
Pounds to Kilograms: For Americans Abroad
If you're American traveling, working out overseas, or buying from international websites, you'll need to convert pounds to kilograms constantly.
Quick Mental Math Trick: To roughly convert lbs to kg: divide by 2, then subtract 10%
- 150 lbs → 75 - 7.5 = ~67.5 kg (actual: 68.0)
- 180 lbs → 90 - 9 = ~81 kg (actual: 81.6)
- 200 lbs → 100 - 10 = ~90 kg (actual: 90.7)
Common Pound to Kilogram Conversions:
| Pounds | Kilograms | Common Context |
|---|---|---|
| 1 lb | 0.454 kg | Grocery item |
| 5 lbs | 2.27 kg | Bag of flour |
| 10 lbs | 4.54 kg | Newborn baby |
| 20 lbs | 9.07 kg | Carry-on luggage limit |
| 50 lbs | 22.7 kg | Checked bag limit (some airlines) |
| 100 lbs | 45.4 kg | |
| 150 lbs | 68.0 kg | Average adult |
| 200 lbs | 90.7 kg |
Airline Baggage (Why This Matters):
- US airlines: typically 50 lbs (23 kg) checked bag limit
- European airlines: often 20-23 kg limits
- Overweight fees kick in at these thresholds
- Knowing the conversion saves you money at check-in!
Ounces and Grams: For Cooking and Baking
When precision matters—like in baking—you need exact conversions between ounces and grams. One wrong measurement can ruin a soufflé or throw off your bread's hydration ratio.
The Key Conversion:
- 1 ounce = 28.35 grams (often rounded to 28g)
- 1 gram = 0.035 ounces
Why Grams Are Better for Baking: Professional bakers worldwide use grams because:
- More precise (no fractions)
- Easier to scale recipes
- Consistent results every time
- Less room for measuring errors
Common Cooking Conversions:
| Ounces | Grams | Common Ingredient |
|---|---|---|
| 1 oz | 28 g | Cheese slice |
| 2 oz | 57 g | Pasta serving |
| 4 oz (¼ lb) | 113 g | Burger patty |
| 8 oz (½ lb) | 227 g | Steak |
| 16 oz (1 lb) | 454 g | Ground beef pack |
Baking Ingredients by Weight:
| Ingredient | 1 Cup | Grams |
|---|---|---|
| All-purpose flour | 1 cup | 120-125 g |
| Sugar (granulated) | 1 cup | 200 g |
| Butter | 1 cup | 227 g |
| Chocolate chips | 1 cup | 170 g |
| Brown sugar (packed) | 1 cup | 220 g |
Pro Tip: Invest in a kitchen scale that shows both ounces and grams. It's a game-changer for consistent baking.
Stone to Pounds: Understanding British Weights
If you've ever watched British TV or read UK health articles, you've encountered "stone"—a unit that confuses Americans and puzzles even some Brits under 30.
What is a Stone?
- 1 stone = 14 pounds = 6.35 kg
- Used primarily in UK and Ireland for body weight
- Officially phased out for trade but culturally persistent
- Named for actual stones used as counterweights historically
Why Stone Persists: The UK officially adopted metric in 1965, but stone stuck around for body weight because:
- It's how parents and grandparents measured
- Gives "rounder" numbers for typical body weights
- British media still uses it
- NHS still records weight in stone
Stone to Pounds/Kilograms Table:
| Stone | Pounds | Kilograms |
|---|---|---|
| 8 st | 112 lbs | 50.8 kg |
| 9 st | 126 lbs | 57.2 kg |
| 10 st | 140 lbs | 63.5 kg |
| 11 st | 154 lbs | 69.9 kg |
| 12 st | 168 lbs | 76.2 kg |
| 13 st | 182 lbs | 82.6 kg |
| 14 st | 196 lbs | 88.9 kg |
| 15 st | 210 lbs | 95.3 kg |
Mixed Stone + Pounds: Brits often say "11 stone 7" meaning 11 stone and 7 pounds (161 lbs / 73 kg).
- 10 st 6 lbs = 146 lbs = 66.2 kg
- 12 st 10 lbs = 178 lbs = 80.7 kg
Shipping and Postage Weight Conversions
Whether you're selling on eBay, shipping internationally, or mailing packages, getting the weight right saves money and avoids surprises.
Shipping Weight Thresholds:
| Service | Weight Limit | In Other Units |
|---|---|---|
| USPS First Class | 13 oz | 368 g / 0.81 lbs |
| USPS Priority Flat Rate | 70 lbs | 31.75 kg |
| UPS Ground | 150 lbs | 68 kg |
| FedEx Express | 150 lbs | 68 kg |
| International Air | 70 lbs | 31.75 kg |
Dimensional vs Actual Weight: Carriers charge by whichever is greater:
- Actual weight: What the scale says
- Dimensional weight: Size-based calculation
E-commerce Shipping Tips:
- Weigh products with packaging
- Round up to nearest ounce for safety
- Include weight in product listings
- Remember: 16 oz = 1 lb exactly
International Shipping Gotchas:
- Canada/Europe use kg exclusively
- Customs forms require metric
- Many countries have 2 kg small packet limits
- DHL/FedEx calculators accept both units
Fitness and Gym Weight Conversions
At the gym, you'll encounter both pounds and kilograms depending on where you are and what equipment you're using.
Olympic Weights Are Metric: Standard Olympic barbells and competition plates are always in kilograms:
| Plates (kg) | In Pounds | Per Side |
|---|---|---|
| 25 kg | 55 lbs | "Big plate" |
| 20 kg | 44 lbs | |
| 15 kg | 33 lbs | |
| 10 kg | 22 lbs | |
| 5 kg | 11 lbs | |
| 2.5 kg | 5.5 lbs | |
| 1.25 kg | 2.75 lbs |
Olympic Barbell:
- Men's bar: 20 kg (44 lbs)
- Women's bar: 15 kg (33 lbs)
Common Gym Lifts Converted:
| Lift | Pounds | Kilograms |
|---|---|---|
| "1 plate" bench | 135 lbs | 61 kg |
| "2 plates" bench | 225 lbs | 102 kg |
| "3 plates" bench | 315 lbs | 143 kg |
| "4 plates" squat | 405 lbs | 184 kg |
| Beginner deadlift | 135 lbs | 61 kg |
| Intermediate deadlift | 315 lbs | 143 kg |
| Advanced deadlift | 500 lbs | 227 kg |
Dumbbell Quick Reference:
- 10 lb dumbbell ≈ 4.5 kg
- 20 lb dumbbell ≈ 9 kg
- 30 lb dumbbell ≈ 13.5 kg
- 50 lb dumbbell ≈ 23 kg
The History of Weight Measurement
Understanding where these units came from helps explain why we're still stuck with such a confusing system.
The Kilogram:
- Created during the French Revolution (1795)
- Originally defined as the mass of 1 liter of water at 4°C
- From 1889-2019, defined by a platinum-iridium cylinder in Paris
- Now defined by the Planck constant (2019 redefinition)
- Goal was a universal, reproducible standard
The Pound:
- Derives from the Roman "libra pondo" (hence "lb")
- Has varied wildly throughout history (300-560 grams!)
- The modern avoirdupois pound was standardized in 1959
- Exactly 453.59237 grams by international agreement
- 16 ounces = 1 pound (but this wasn't always true)
The Stone:
- Originally the weight of a standard trading stone
- Varied by region and commodity
- Standardized at 14 pounds in 1835 (UK)
- Still used colloquially for body weight in UK/Ireland
The Ounce:
- From Latin "uncia" (1/12th)
- Confusingly, there are multiple types of ounces:
- Avoirdupois ounce: 28.35 g (what we use)
- Troy ounce: 31.1 g (for precious metals)
- Fluid ounce: volume, not weight!
Why Metric Won: The metric system's beauty is its base-10 simplicity:
- 1000 mg = 1 g
- 1000 g = 1 kg
- 1000 kg = 1 metric ton
Meanwhile, imperial gives us: 16 drams = 1 ounce, 16 ounces = 1 pound, 14 pounds = 1 stone, 2000 pounds = 1 ton...
Medical and Pharmaceutical Weight Conversions
In healthcare, precision weight measurements can be life-or-death—especially for medication dosing.
Medication Dosing Units:
| Unit | Equivalent | Common Use |
|---|---|---|
| 1 gram (g) | 1,000 mg | Antibiotics, vitamins |
| 1 milligram (mg) | 1,000 mcg | Most prescription drugs |
| 1 microgram (mcg/μg) | 0.001 mg | Thyroid meds, folic acid |
| 1 grain (gr) | 64.8 mg | Aspirin, older prescriptions |
Weight-Based Dosing: Many medications are dosed by body weight, especially for children:
- Pediatric doses: typically mg/kg of body weight
- Chemotherapy: often calculated per m² of body surface area
- Anesthesia: precise weight needed for safe dosing
Why Hospitals Use Metric:
- Eliminates conversion errors
- International drug databases use metric
- Decimal system prevents fraction mistakes
- WHO recommends metric for all medical records
Common Medical Weight Conversions:
| Patient Weight | Kilograms | For Dosing |
|---|---|---|
| Newborn | 2.5-4 kg | 5.5-8.8 lbs |
| 1 year old | 9-10 kg | 20-22 lbs |
| 5 year old | 18-20 kg | 40-44 lbs |
| Adult female avg | 70 kg | 154 lbs |
| Adult male avg | 84 kg | 185 lbs |
Critical Note: Never estimate patient weight for medication dosing. Even small errors can lead to underdosing (ineffective treatment) or overdosing (toxicity). Always use calibrated medical scales.
Precious Metals: Troy vs Avoirdupois Weights
Gold, silver, and platinum use a completely different weight system than everyday items—and mixing them up is expensive!
Troy Weight System:
- Used exclusively for precious metals
- 1 troy ounce = 31.1035 grams
- 1 avoirdupois ounce = 28.3495 grams
- Troy ounce is ~10% heavier than regular ounce!
Why Troy Ounces? Named after Troyes, France—a major medieval trading center for precious metals. The system predates the avoirdupois system and stuck around because:
- Established pricing conventions
- International gold markets standardized on troy
- Changing would cause market chaos
Gold Weight Conversions:
| Troy Ounces | Grams | Avoirdupois Oz | Common Form |
|---|---|---|---|
| 1 ozt | 31.1 g | 1.097 oz | Gold coin |
| 10 ozt | 311 g | 10.97 oz | Small bar |
| 32.15 ozt | 1,000 g | 35.27 oz | 1 kg bar |
| 100 ozt | 3,110 g | 109.7 oz | Large bar |
| 400 ozt | 12,441 g | 438.9 oz | "Good Delivery" bar |
2026 Gold Price Context:
- Gold trades at ~$2,050/troy ounce (as of early 2026)
- 1 gram of gold ≈ $66
- The troy/avoirdupois difference = ~$205 per "ounce" error!
Silver and Platinum:
- Silver: ~$24/troy ounce
- Platinum: ~$1,000/troy ounce
- All quoted in troy ounces on commodity exchanges
Jewelry Weight: Jewelry often uses grams or pennyweight (dwt):
- 1 pennyweight = 1.555 grams
- 20 pennyweight = 1 troy ounce
- Used by jewelers for pricing repairs and custom work
International Food Labels and Nutrition
Understanding weight on food labels helps you compare products internationally and track nutrition accurately.
US vs International Labels:
| Component | US Label | International |
|---|---|---|
| Serving size | Cups/oz | Grams/mL |
| Net weight | Oz and g | Grams only |
| Nutrients | Per serving | Per 100g |
Why "Per 100g" Is Better: International labels show nutrition per 100 grams, making comparison easy:
- Compare any two products directly
- No serving size manipulation
- Calculate exact intake mathematically
Common Package Sizes:
| US Size | Metric Equivalent |
|---|---|
| 12 oz can | 355 mL |
| 16 oz (1 lb) | 454 g |
| 2 liter bottle | 67.6 fl oz |
| 100 g bar | 3.5 oz |
| 500 g package | 1.1 lbs |
| 1 kg bag | 2.2 lbs |
Nutrition Tracking Tips:
- Weigh food in grams for accuracy
- "1 serving" varies wildly between brands
- Use 100g values for meal planning
- Digital food scales are cheap and essential for macro tracking
International Shopping: When buying food abroad or from international websites:
- European products: always metric
- Asian products: often metric or local units
- UK products: mix of imperial and metric
- Australian products: fully metric
Pro Tips
- 💡For kg to lbs: double it and add 10%. It's not exact but gets you within 1% for quick estimates.
- 💡Remember: 1 kg ≈ 2.2 lbs. Just multiply by 2.2 for most practical purposes.
- 💡At the gym, Olympic plates are always in kg. A "plate" (big one) is 20 kg or 45 lbs.
- 💡For baking, invest in a kitchen scale that shows both grams and ounces—it's a game changer.
- 💡Airline baggage: 23 kg = 50 lbs is the magic number. Memorize it to avoid overweight fees.
- 💡British body weight uses stone (14 lbs = 1 stone). 10 stone = 140 lbs = 63.5 kg.
- 💡When shipping internationally, always use metric—customs forms require kilograms.
- 💡For cooking: 1 oz ≈ 28g. Round to 30g if you need a quick mental estimate.
- 💡Gold and precious metals use troy ounces (31.1g), not regular ounces (28.35g). Don't mix them up!
- 💡The metric system is base-10: 1000g = 1kg, 1000kg = 1 metric ton. Much easier than imperial!
- 💡Body weight changes about 2-4 lbs (1-2 kg) throughout the day due to food, water, and waste.
- 💡For fitness tracking: most apps let you switch between kg/lbs in settings. Choose one and stick with it.
Frequently Asked Questions
One kilogram equals exactly 2.20462 pounds. For quick mental math, just double the kilograms and add 10%. So 70 kg is roughly 140 + 14 = 154 lbs (actual: 154.3 lbs). This is the most common weight conversion worldwide, especially for body weight, luggage limits, and international shipping.
