Oz to Kg Converter
Weight Converter
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Convert ounces to kilograms quickly and accurately with our comprehensive conversion tool. Whether you’re cooking, shipping packages, or working with different measurement systems, get precise results instantly.
Important: Types of Ounces
This converter handles WEIGHT ounces (avoirdupois ounces)
- 1 ounce (oz) = 0.0283495 kilograms (kg)
- 1 kilogram (kg) = 35.274 ounces (oz)
Not to be confused with:
- Fluid ounces (volume measurement for liquids)
- Troy ounces (precious metals and jewelry)
Quick Conversion Formulas
Ounces to Kilograms
Formula: oz ÷ 35.274 = kg
- Example: 100 oz ÷ 35.274 = 2.835 kg
Kilograms to Ounces
Formula: kg × 35.274 = oz
- Example: 5 kg × 35.274 = 176.37 oz
Essential Conversion Tables
Common Food Portions (oz to kg)
| Ounces (oz) | Kilograms (kg) | Common Food Example |
|---|---|---|
| 1 oz | 0.028 kg | 1 slice of bread |
| 4 oz | 0.113 kg | Burger patty |
| 8 oz | 0.227 kg | Cup of milk |
| 16 oz | 0.454 kg | 1 pound of butter |
| 32 oz | 0.907 kg | Large bag of flour |
| 64 oz | 1.814 kg | Large container yogurt |
Package Shipping Weights
| Ounces (oz) | Kilograms (kg) | Shipping Category |
|---|---|---|
| 1-3 oz | 0.028-0.085 kg | Letter/document |
| 4-8 oz | 0.113-0.227 kg | Small package |
| 16 oz | 0.454 kg | Standard package |
| 32 oz | 0.907 kg | Medium package |
| 64 oz | 1.814 kg | Large package |
| 80 oz | 2.268 kg | Extra large package |
Extended Conversion Chart
| Ounces | Kilograms | Pounds + Ounces |
|---|---|---|
| 0.5 oz | 0.014 kg | 0 lb 0.5 oz |
| 1 oz | 0.028 kg | 0 lb 1 oz |
| 2 oz | 0.057 kg | 0 lb 2 oz |
| 4 oz | 0.113 kg | 0 lb 4 oz |
| 8 oz | 0.227 kg | 0 lb 8 oz |
| 12 oz | 0.340 kg | 0 lb 12 oz |
| 16 oz | 0.454 kg | 1 lb 0 oz |
| 24 oz | 0.680 kg | 1 lb 8 oz |
| 32 oz | 0.907 kg | 2 lb 0 oz |
| 48 oz | 1.361 kg | 3 lb 0 oz |
| 64 oz | 1.814 kg | 4 lb 0 oz |
| 80 oz | 2.268 kg | 5 lb 0 oz |
| 96 oz | 2.722 kg | 6 lb 0 oz |
| 128 oz | 3.629 kg | 8 lb 0 oz |
| 160 oz | 4.536 kg | 10 lb 0 oz |
Cooking and Baking Applications
Recipe Conversion Guide
Converting US Recipes to Metric:
| US Measurement | Ounces | Kilograms | Metric Equivalent |
|---|---|---|---|
| 1/4 cup flour | 1.1 oz | 0.031 kg | 31 grams |
| 1/2 cup flour | 2.2 oz | 0.062 kg | 62 grams |
| 1 cup flour | 4.4 oz | 0.125 kg | 125 grams |
| 1 cup sugar | 7.1 oz | 0.200 kg | 200 grams |
| 1 cup butter | 8 oz | 0.227 kg | 227 grams |
| 1 cup rice | 6.5 oz | 0.184 kg | 184 grams |
Meat Portions by Weight
| Portion Size | Ounces | Kilograms | Serves |
|---|---|---|---|
| Individual steak | 6-8 oz | 0.17-0.23 kg | 1 person |
| Chicken breast | 4-6 oz | 0.11-0.17 kg | 1 person |
| Ground beef patty | 4 oz | 0.11 kg | 1 burger |
| Roast chicken | 48-64 oz | 1.36-1.81 kg | 4-6 people |
| Whole turkey | 160-240 oz | 4.54-6.80 kg | 8-12 people |
International Shopping Guide
Understanding Package Labels
US Products to International:
- 12 oz can = 0.340 kg
- 16 oz package = 0.454 kg
- 32 oz bottle = 0.907 kg
- 5 lb bag = 80 oz = 2.268 kg
Price Comparison Conversions:
- Price per oz × 35.274 = Price per kg
- Price per kg ÷ 35.274 = Price per oz
Example: If nuts cost $0.50 per oz
- $0.50 × 35.274 = $17.64 per kg
Pharmaceutical and Medical Uses
Medication Dosage Context
Important Note: Always consult healthcare providers for medication conversions.
| Body Weight (Common) | Ounces | Kilograms | Medical Context |
|---|---|---|---|
| Newborn baby | 112-140 oz | 3.2-4.0 kg | Pediatric dosing |
| 1-year-old | 352 oz | 10 kg | Child dosing reference |
| Adult female | 2204 oz | 62.5 kg | Standard adult dosing |
| Adult male | 2822 oz | 80 kg | Standard adult dosing |
Pet Medication Reference
| Pet Size | Weight Range (oz) | Weight Range (kg) | Common Pets |
|---|---|---|---|
| Tiny | 35-70 oz | 1-2 kg | Chihuahua, hamster |
| Small | 176-352 oz | 5-10 kg | Cat, small dog |
| Medium | 705-1058 oz | 20-30 kg | Beagle, bulldog |
| Large | 1411-2116 oz | 40-60 kg | German shepherd |
| Extra Large | 2469+ oz | 70+ kg | Great Dane |
Industrial and Scientific Applications
Laboratory Measurements
| Sample Size | Ounces | Kilograms | Lab Application |
|---|---|---|---|
| Micro sample | 0.001 oz | 0.000028 kg | Chemical analysis |
| Small sample | 0.1 oz | 0.0028 kg | Quality testing |
| Standard sample | 1 oz | 0.028 kg | Material testing |
| Large sample | 10 oz | 0.28 kg | Bulk analysis |
Manufacturing Tolerances
Precision Requirements by Industry:
- Pharmaceuticals: ±0.001 oz (±0.000028 kg)
- Food production: ±0.1 oz (±0.0028 kg)
- Chemical manufacturing: ±0.01 oz (±0.00028 kg)
- Jewelry/precious metals: Use troy ounces instead
Postal and Shipping Guidelines
International Shipping Limits
| Service Type | Max Weight (oz) | Max Weight (kg) | Notes |
|---|---|---|---|
| Standard letter | 3.5 oz | 0.099 kg | Most countries |
| Large envelope | 13 oz | 0.369 kg | Documents only |
| Small package | 35 oz | 0.992 kg | Economy shipping |
| Standard package | 70 oz | 1.984 kg | Regular rates |
| Express package | 70 oz | 1.984 kg | Faster delivery |
Shipping Cost Brackets (USPS Example)
| Weight Range (oz) | Weight Range (kg) | Cost Category |
|---|---|---|
| 0-1 oz | 0-0.028 kg | Letters |
| 1-3 oz | 0.028-0.085 kg | Large envelopes |
| 3-13 oz | 0.085-0.369 kg | First-Class Package |
| 13-70 oz | 0.369-1.984 kg | Priority Mail |
| 70+ oz | 1.984+ kg | Priority Mail Express |
Precious Metals – Troy Ounces
Important Distinction: Precious metals use troy ounces, NOT standard ounces.
| Troy Ounces | Standard Ounces | Kilograms | Metal |
|---|---|---|---|
| 1 troy oz | 1.097 oz | 0.0311 kg | Gold/Silver unit |
| 10 troy oz | 10.97 oz | 0.311 kg | Small bar |
| 32.15 troy oz | 35.27 oz | 1.000 kg | 1 kg gold bar |
Troy Ounce Formula:
- 1 troy ounce = 31.1035 grams = 0.0311 kg
- 1 kg = 32.15 troy ounces
Sports and Fitness Applications
Boxing Weight Classes (Amateur)
| Weight Class | Limit (oz) | Limit (kg) | Division |
|---|---|---|---|
| Flyweight | 1867 oz | 52.9 kg | Light |
| Bantamweight | 1962 oz | 55.6 kg | Light |
| Featherweight | 2009 oz | 57.0 kg | Light |
| Lightweight | 2116 oz | 60.0 kg | Light |
| Welterweight | 2469 oz | 70.0 kg | Medium |
| Middleweight | 2646 oz | 75.0 kg | Medium |
| Heavyweight | 3175+ oz | 90.1+ kg | Heavy |
Weightlifting Equipment
| Equipment | Weight (oz) | Weight (kg) | Use |
|---|---|---|---|
| Standard plate | 88 oz | 2.5 kg | Home gym |
| Olympic plate | 176 oz | 5 kg | Professional |
| Dumbbell (light) | 35 oz | 1 kg | Rehab/seniors |
| Dumbbell (medium) | 176 oz | 5 kg | General fitness |
| Dumbbell (heavy) | 705 oz | 20 kg | Strength training |
| Kettlebell | 564 oz | 16 kg | Functional fitness |
Historical Context and Definitions
Origin of the Ounce
Avoirdupois Ounce (Weight):
- Derived from Roman “uncia” meaning “twelfth part”
- Standardized in 1959 as exactly 28.349523125 grams
- 1/16 of an avoirdupois pound
- Used primarily in United States and few other countries
Countries Using Ounces:
- United States (primary)
- Liberia (limited use)
- Myanmar (transitioning to metric)
- UK (informal use in some contexts)
Scientific Definition Updates
Modern Kilogram (2019 Redefinition):
- Now defined by Planck’s constant
- Previously defined by physical prototype in France
- More stable and reproducible standard
- Maintains same practical size and relationships
Common Conversion Mistakes to Avoid
Frequent Errors
- Confusing fluid ounces with weight ounces
- ❌ Using 1 fl oz = 0.0295 kg (this is volume!)
- ✅ Using 1 weight oz = 0.0283 kg
- Mixing troy and avoirdupois ounces
- ❌ Using standard oz for gold/silver
- ✅ Using troy oz for precious metals
- Rounding errors in pharmaceutical contexts
- ❌ Using 35 instead of 35.274 for medical calculations
- ✅ Using precise conversion factors
- Context-inappropriate precision
- ❌ Giving 6 decimal places for cooking
- ✅ Using appropriate precision for the application
Regional Usage Patterns
Where Ounces Are Still Common
United States:
- Food packaging and nutrition labels
- Postal services and shipping
- Retail products and portions
- Recipe measurements
- Body weight (informal)
Other Countries:
- UK: Beer sales, some food items
- Canada: Some food packaging (dual labeling)
- Bahamas: Limited use
Scientific/International:
- Generally use metric (kg/grams)
- Exception: Troy ounces for precious metals globally
Quick Reference Formulas
Mental Math Shortcuts
Ounces to Kilograms:
- Divide by 35 (approximate)
- Or divide by 36 for quick estimate
- 100 oz ÷ 35 ≈ 2.86 kg (actual: 2.835 kg)
Kilograms to Ounces:
- Multiply by 35 (approximate)
- Or multiply by 36 for quick estimate
- 3 kg × 35 ≈ 105 oz (actual: 105.82 oz)
Cooking Conversions:
- 1 cup ≈ 8 oz ≈ 0.23 kg
- 1 pound = 16 oz = 0.454 kg
- 1 stick butter = 4 oz = 0.113 kg
Frequently Asked Questions
Q: What’s the difference between weight ounces and fluid ounces? A: Weight ounces measure mass (like this converter), while fluid ounces measure volume of liquids. They’re completely different units.
Q: Why doesn’t the US use kilograms? A: Historical reasons. The US adopted the imperial system before metric standardization and has been slow to transition, unlike most other countries.
Q: Are troy ounces the same as regular ounces? A: No. Troy ounces (31.1g) are heavier than avoirdupois ounces (28.35g) and are used only for precious metals.
Q: How precise do I need to be? A: Depends on context:
- Cooking: 1-2 decimal places
- Shipping: 1 decimal place
- Medicine: 3+ decimal places
- Science: As precise as needed
Q: Can I use this for liquid measurements? A: Only if you know the liquid’s density. This converts weight ounces to kg. For liquids, you typically need fluid ounces to liters conversion.