What Is Ounces to Grams Conversion?

Ounces are the standard small weight unit in the United States, while grams are used internationally. Converting between them is necessary for shipping abroad, sharing recipes globally, and understanding metric product labels.

When You Need This Conversion

International shipping — Customs forms require gram weights
Sharing recipes — Converting for metric-using audiences
Buying imported products — Understanding gram labels
Science and medicine — Metric is the standard
Postal services — Many countries use gram-based rates
E-commerce — Product specifications for global markets

The Conversion Factor

One ounce equals exactly 28.3495 grams. For quick calculations, multiply ounces by 28 for a close approximation.

Why Grams Are the Global Standard

The gram is part of the metric system, adopted by nearly every country. International commerce, science, and postal services standardize on grams for consistency.

How to Convert Ounces to Grams

Using This Converter

Enter the weight in ounces in the left field
See the gram equivalent instantly
Use swap to convert grams to ounces
Copy results for shipping labels or documents

Quick Mental Math

Multiply by 28 — Close approximation
Multiply by 30 — Easier math, slightly over

Common Reference Points

1 oz = 28.35g (single letter weight)
2 oz = 56.7g (thick envelope)
4 oz = 113g (small package)
8 oz = 227g (half pound)
16 oz = 454g (one pound)

For International Shipping

When shipping to most countries, convert ounce weights to grams for customs declarations. This ensures accurate duty calculation and prevents shipping delays.

Features & Use Cases

Instant Bidirectional Conversion

Switch between ounces→grams and grams→ounces with one click. Useful when comparing US and international product weights.

Common Use Cases

International Shipping

Customs forms worldwide require gram weights. Convert your ounce measurements accurately to avoid delays and ensure correct duty assessment.

Recipe Sharing

When posting American recipes online for international audiences, convert ounce measurements to grams for wider accessibility.

Product Comparison

Compare products sold in different markets. A 12 oz package in the US equals 340g — useful for price comparison with metric-labeled alternatives.

Postal Services

Many postal services outside the US use gram-based rate tiers. Convert to find the right rate for international mail.

Science & Education

Academic work requires metric units. Convert any ounce-based data to grams for proper scientific notation.

Reference Table

The quick reference shows common postal weights, helping you estimate shipping costs at a glance.

Frequently Asked Questions

How many grams are in an ounce?

One ounce equals exactly 28.3495 grams. For most purposes, 28g per oz is accurate enough.

How do I convert ounces to grams for shipping?

Multiply your ounce weight by 28.35. For a 6 oz package: 6 × 28.35 = 170 grams. Round up for safety.

Is there a difference between food ounces and postal ounces?

No, avoirdupois ounces are standard for both. However, precious metals use troy ounces (31.1g), which are different.

Why don't American recipes use grams?

American home cooking traditionally uses volume measures (cups, tablespoons). Professional bakers often do use grams for precision.

What's 8 oz in grams?

8 ounces equals 226.8 grams, commonly rounded to 227g. This is half a pound or about 250ml of water.

How accurate does my conversion need to be?

For cooking, ±5g won't matter. For shipping and customs, round up to the nearest gram. For science, use the full precision (28.3495).

Ounces to Grams