What is the weight of a silver Mercury or Roosevelt dime in troy ounces?
Executive summary
A U.S. 90% silver Mercury dime (1916–1945) and a 90% silver Roosevelt dime (1946–1964) each have a total mass of about 2.5 grams and contain roughly 90% silver by weight, which industry sources translate to about 0.0723–0.07234 troy ounces of pure silver per coin (while the whole coin’s weight in troy ounces is commonly listed near 0.0804 troy oz) [1] [2] [3] [4] [5] [6].
1. The basic numbers: coin mass and alloy stated by multiple bullion dealers
Numismatic and bullion retailers uniformly report that pre‑1965 dimes struck in the U.S. — Mercury dimes (1916–1945) and silver Roosevelt dimes (through 1964) — were struck in a 90% silver / 10% copper alloy and that each coin’s minted mass is 2.5 grams, a figure cited across product pages and guides [1] [4] [7] [5].
2. How that mass converts to troy ounces: whole coin vs. silver content
When dealers convert the 2.5‑gram minted mass into troy ounces they commonly report the entire coin weighing about 0.0804 troy ounces (a conversion explicitly shown by at least one source) [6], and they then apply the 90% silver purity to give the bullion (melt) silver contained in each dime — reported by multiple sellers as about 0.0723 to 0.07234 troy ounces of pure silver per coin [1] [2] [3] [5].
3. Minor discrepancies in published figures and why they appear
A few online calculators and vendor pages list slightly different per‑coin silver numbers (for example 0.0715 troy oz in one calculator and small rounding differences elsewhere) [8] [4], reflecting either rounding, differing unit conversions, or typographic variance; the dominant, repeated figure used by major bullion merchants is ~0.07234 troy ounces of silver per 90% dime [2] [3] [5].
4. Practical implication for melt value and stacking
Dealers selling bulk face‑value lots use the per‑dime silver weight to compute total troy ounces in a roll or bag — for example a $100 face‑value bag of Mercury dimes is listed as containing roughly 71.5 troy ounces of silver (which aligns with about 0.715 troy oz of silver per dollar of face value using the ~0.07234 per‑dime figure) [9] [3]. This is the number used to calculate bullion melt value against the current silver spot price rather than any numismatic premium the coin might carry [3].
5. Sources, motives and where to be cautious
The consensus figures are drawn from coin dealers and bullion sellers who have a commercial incentive to present clean, simple melt‑value math [2] [3] [9]; small variations in published per‑coin weights on hobby or retail sites can reflect rounding, marketing copy, or calculator formulas [8] [4]. If exact arithmetic is required for a large lot, consulting the mint specification and performing the gram→troy‑ounce conversion (1 troy oz = 31.1034768 g) or using established bullion tables used by multiple dealers is recommended — those tables underpin the commonly quoted 0.07234 troy oz figure cited by several vendors [2] [3] [5].
6. Bottom line answer (concise and authoritative)
A silver Mercury or Roosevelt dime minted as 90% silver weighs 2.5 grams in total (commonly listed as ~0.0804 troy ounces total weight) and contains roughly 0.0723–0.07234 troy ounces of pure silver per coin; minor published variations exist but the prevailing industry standard used for melt calculations is ~0.07234 troy ounces of silver per dime [1] [2] [3] [6] [5].