How many grams are in one dram (avoirdupois)?

One avoirdupois dram is defined as one sixteenth of an avoirdupois ounce and corresponds to approximately 1.771845 grams. The calculator uses this exact factor for conversions.

How many grams are in one apothecaries dram?

One apothecaries dram corresponds to 60 grains and is equal to roughly 3.8879346 grams. This is about 2.2 times heavier than an avoirdupois dram, so choosing the correct system in the converter is essential.

What is the difference between avoirdupois and apothecaries drams?

Both are historical units called dram, but they belong to different systems. The avoirdupois dram is part of the everyday imperial weight system based on 16 ounces per pound, while the apothecaries dram derives from the old pharmacy system with 12 ounces per pound. They have different gram equivalents, so they are not interchangeable.

Can I use this tool to calculate medical doses?

No. This converter is intended only for historical, educational and non-medical technical use. Do not use it for prescribing or adjusting any medication. Always follow current medical guidelines and a licensed professional’s instructions.

Can the calculator convert grams to drams as well?

Yes. You can choose grams as the input unit and either avoirdupois drams or apothecaries drams as the output unit. The tool will convert in both directions using the appropriate factors.

Dram to Grams Converter – Avoirdupois & Apothecaries (dr ⇄ g)

How to Use This Converter

Enter the value you want to convert, pick the original unit, and select the target unit. The calculator uses grams as a pivot to keep both directions aligned and shows the equivalent amounts next to the main result.

Type the numeric value you want to convert.

Choose whether the entry starts in grams or one of the dram systems.

Select the target unit—grams or one of the dram systems.

Hit Calculate or wait a moment for the values to refresh automatically.

Methodology

The converter pivots every calculation through grams. It applies the exact factors used historically for avoirdupois and apothecaries drams and then rounds the display to six decimal places with exponential notation for very large or small magnitudes.

Key factors: 1 avoirdupois dram = 1.7718451953125 grams, 1 apothecaries dram = 3.8879346 grams.

Full original guide (expanded)

Quick reference: drams to grams

The table below compares avoirdupois and apothecaries drams for common small integer values.

Drams (dr)	Grams (avdp)	Grams (apothecaries)
1	1.771845	3.887935
2	3.543690	7.775869
4	7.087381	15.551738
8	14.174761	31.103477
16	28.349922	62.206954

Understanding the dram units

The term dram (or drachm) appears in more than one historical system of units. For mass, the two most commonly referenced are:

Avoirdupois dram – part of the everyday imperial system used for goods, where 16 ounces make one pound.
Apothecaries dram – part of the historical pharmacy system, where 12 ounces make one pound.

Exact relationships used in this calculator

From drams to grams

Grams from avoirdupois drams: \(\text{g} = \text{dr}_{\text{av}} \times 1.7718451953\)

Grams from apothecaries drams: \(\text{g} = \text{dr}_{\text{ap}} \times 3.8879346\)

From grams to drams

Avoirdupois drams: \(\text{dr}_{\text{av}} = \dfrac{\text{g}}{1.7718451953}\)

Apothecaries drams: \(\text{dr}_{\text{ap}} = \dfrac{\text{g}}{3.8879346}\)

Worked example: 5 drams (avdp) to grams

Select From: drams (avoirdupois) and To: grams.
Enter value 5 in the main field.
The calculator multiplies 5 × 1.771845 ≈ 8.859225 g.
The synchronized view also shows the equivalent apothecaries drams for the same gram value.

Worked example: 10 grams to apothecaries drams

Select From: grams and To: drams (apothecaries).
Enter value 10.
The calculator divides 10 by 3.8879346, giving approximately 2.571 dr (apothecaries).
The synchronized view shows the equivalent value in avoirdupois drams as well.

FAQ: dram to grams conversions

Which dram should I use for non-medical technical work?

For most non-medical, non-pharmacy applications, if a “dram” appears without further context, it is usually safer to assume the avoirdupois dram. If you are dealing with historical pharmaceutical recipes or texts, the apothecaries dram is more likely.

Why is there a warning about medical use?

Modern pharmacology uses the metric system (mg, g, mL) with strictly defined dosing protocols. Historical dram-based prescriptions are not meant to be recreated directly. This converter is purely educational and technical, not a substitute for medical judgment.

Why do different websites show slightly different decimal values?

The underlying conversion factors are exact or well-established, but different tools may round at different stages or show fewer digits. This calculator keeps sufficient precision internally and rounds the display to a practical number of decimals for readability.

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