Pennyweight to Grams Converter

Convert between pennyweight (dwt) and grams (g) using the exact troy-weight relationships. The tool also shows equivalent troy ounces and grains, making it ideal for jewelry workshops, bullion dealers, assay labs and appraisers.

Calculation engine based on 1 dwt = 24 grains, 1 grain = 0.06479891 g, 1 troy ounce = 20 dwt.

dwt ⇄ grams conversion

Troy system / SI
Conversion direction

Suitable for casting trees, scrap lots, investment bars and calibrated jewelry components.

Results

Pennyweight (dwt):
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Grams (g):
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Troy ounces (ozt):
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Grains (gr):
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Enter a value and click “Convert” to see the equivalent in grams, troy ounces and grains.

Pennyweight to grams – quick reference table

This table provides common dwt values with their gram, troy ounce and grain equivalents. Handy at the bench when you want a quick check without a calculator.

Pennyweight (dwt) Grams (g) Troy ounces (ozt) Grains (gr)

All values are based on 1 dwt = 1.55517384 g = 24 grains and are rounded to a practical number of decimals.

What is a pennyweight (dwt)?

The pennyweight (abbreviated dwt) is a unit of mass in the troy weight system. It is widely used in jewelry manufacturing, precious metal trading and dental alloys. In the modern definition:

Exact relationships

1 pennyweight (dwt) = 24 grains (gr)

1 grain = 0.06479891 grams

⇒ 1 dwt = 24 × 0.06479891 g = 1.55517384 grams

Pennyweight is part of the same system as troy ounces, not to be confused with the avoirdupois ounce (used for everyday items). In troy weight:

  • 1 troy ounce (ozt) = 20 dwt
  • 1 troy ounce = 480 grains
  • 1 troy ounce ≈ 31.1034768 grams

Formulas used by the pennyweight ⇄ grams calculator

Pennyweight to grams

Formula

Let mdwt be the mass in pennyweight.

grams = m_dwt × 1.55517384

Example: 10 dwt → 10 × 1.55517384 ≈ 15.5517 g

Grams to pennyweight

Formula

Let mg be the mass in grams.

pennyweight = m_g ÷ 1.55517384

Example: 5 g → 5 ÷ 1.55517384 ≈ 3.214 dwt

Derived conversions (troy ounces, grains, carats)

Troy relationships

  • troy ounces: ozt = dwt ÷ 20
  • grains: grains = dwt × 24

Optional: carats (for gemstones)

1 carat = 0.2 g, so carats = grams ÷ 0.2.

Worked examples

Example 1 – Convert 12 dwt to grams and troy ounces

  1. Grams: 12 dwt × 1.55517384 ≈ 18.6621 g.
  2. Troy ounces: 12 dwt ÷ 20 = 0.6 ozt.
  3. Grains: 12 × 24 = 288 grains.

Example 2 – Convert 7.5 g of gold to pennyweight

  1. Pennyweight: 7.5 g ÷ 1.55517384 ≈ 4.822 dwt.
  2. Troy ounces: 4.822 ÷ 20 ≈ 0.2411 ozt.
  3. Grains: 4.822 × 24 ≈ 115.7 grains.

Best practices in professional use

In jewelry and bullion applications, small numeric differences can have significant financial impact. To minimise errors:

  • Use a calibrated scale with an appropriate resolution (e.g. 0.01 g or better).
  • Record weights in grams in your internal systems, then convert to dwt/ozt for legacy workflows.
  • Clearly indicate the unit in all documents and price lists (for example “Price per dwt (14K)” or “Price per gram (24K)”).
  • When invoicing or buying scrap, keep at least 3–4 decimal places during calculation and only round at the final step.

This calculator follows the standard relationships used by major refineries and assay offices, but cannot replace your local legal metrology requirements. Always follow your jurisdiction’s regulations on weights and measures.

Frequently asked questions about pennyweight and grams

Why do jewelers still use pennyweight instead of grams? ▾
Pennyweight is deeply rooted in the troy system historically used for gold, silver and platinum. Many price lists, labor formulas and legacy documents are expressed in dwt, especially in North America. However, grams are increasingly common for international trading and are the SI standard, which is why a reliable converter is essential.
Can I mix troy ounces and regular ounces in calculations? ▾
No. The troy ounce (used for precious metals) is about 31.103 g, while the avoirdupois ounce (used for most other goods) is about 28.35 g. Mixing the two leads to systematic errors. When working with pennyweight you are always in the troy system, so make sure any “oz” you use is explicitly troy ounces (ozt).
What rounding is appropriate when buying and selling gold? ▾
Many shops weigh to 0.01 g or 0.001 ozt and keep at least 3–4 decimal places in intermediate calculations. The final invoice is often rounded to 2 decimal places in the currency, not in the weight. Consistency and transparent rounding rules are more important than the exact convention chosen.
Is there any difference between “dwt” and “pwt”? ▾
Historically both abbreviations were used, but dwt (from denarius weight) is the standard modern abbreviation in jewelry and bullion contexts. This calculator assumes dwt as the unit symbol.
Can I use this tool for dental alloys and laboratory work? ▾
Yes. The underlying physics is the same for all precious metal applications. For laboratory protocols and regulated medical materials, always verify that your internal documentation uses the same unit conventions (troy vs SI) and roundings as this calculator.