Source Naturals Magtein Magnesium L-Threonate 667 mg

Mass budget · computed; capsule comparison · modelled

What the declared salt would weigh

Source Naturals Magtein Magnesium L-Threonate 667 mg declares 147 mg of elemental magnesium per serving in NIH DSLD 274903, requiring 1,781.82 mg of magnesium l-threonate under the salt model calculated 2026-09-13.

Size 0 holds about 545 mg, size 00 about 730 mg, and size 000 about 1,100 mg at powder density 0.6–0.8 g/mL. These are model inputs, not measurements of this product's capsule. Read the mass-budget method.

Label facts and derived measurements

The numbers for this label

Source Naturals Magtein Magnesium L-Threonate 667 mg has 14 published fields below, traced to NIH DSLD 274903 and the 2026-08-10 registry snapshot, with calculations dated 2026-09-13.

Observed means a value transcribed from a label or price observation. Computed means arithmetic or normalization of those inputs. Modelled means the result depends on a stated physical assumption, including capsule capacity. Evidence tiers and their limits.

Source transcription · observed

Magnesium lines as filed

Source Naturals Magtein Magnesium L-Threonate 667 mg retains 1 magnesium-related rows in NIH DSLD 274903, including 1 rows selected for the primary serving, from label 2022-09-22, examined 2026-09-13.

The elemental amount comes from the selected magnesium line. A salt named under another nutrient does not make that nutrient's quantity an elemental magnesium value. Distinct unresolved primary amounts remain ambiguous; they are not added together.

Within one salt · computed from observed prices

Cost per 100 mg within threonate

Source Naturals Magtein Magnesium L-Threonate 667 mg's $0.3491 per 100 mg of elemental magnesium is at percentile 100 among 3 threonate labels with observed prices, using confirmed gold-set matches observed 2026-08-10 to 2026-09-07, calculated 2026-09-13.

Percentile = 100 × the number of prices at or below this EC100 ÷ the number of observed prices in this salt, rounded to an integer. Ties receive the same percentile. The comparison includes this label; a high percentile means higher observed cost. Price is the dated item observation, excluding tax, shipping, coupons and subscriptions.

Package arithmetic · observed inputs, computed totals

What the package works out to

Source Naturals Magtein Magnesium L-Threonate 667 mg works out to 60 days per package at the label's own serving and filed frequency of 1 servings per day, according to label 2022-09-22, calculated 2026-09-13.

Days = filed servings per container ÷ filed servings per day. If the label gives a frequency range, the largest frequency gives the shortest duration. Cost per serving = observed item price ÷ filed servings; cost per label-day multiplies this by the filed frequency. This follows the label's own instructions; it is package arithmetic, not intake advice.

Percent daily value · observed and computed

The label's percent daily value, recomputed

Source Naturals Magtein Magnesium L-Threonate 667 mg files 1 magnesium percent-daily-value entries in NIH DSLD 274903; the check below applies the group-specific references in 21 CFR 101.9 to its 147 mg primary serving, calculated 2026-09-13.

Percent daily value = declared elemental mg ÷ the group's reference mg × 100, rounded to an integer. The adult and age-four-plus reference is 420 mg. Historical labels can use earlier references; a difference does not establish a filing error. Full-record entries may cover multiple serving sizes, so this table identifies the primary-serving basis explicitly. Group references and interpretation.

Composition · observed

Other ingredients in the filed record

Source Naturals Magtein Magnesium L-Threonate 667 mg lists 4 other ingredients in NIH DSLD 274903, label dated 2022-09-22, examined 2026-09-13.

Capsule material: gelatin. The material classification follows the filed ingredient names; it is not a test of the shell.

This label lists magnesium stearate, whose reference elemental fraction is 4.1% by mass. No stearate quantity is available in this record as of 2026-09-13, so its magnesium contribution cannot be quantified or added to the Supplement Facts magnesium total.

Label declarations · observed

Target groups as filed

Source Naturals Magtein Magnesium L-Threonate 667 mg has 3 target-group entries in NIH DSLD 274903, label dated 2022-09-22, examined 2026-09-13.

Provenance · observed

Registry record, versions and scanned label

The registry holds 1 versions of this label for Source Naturals Magtein Magnesium L-Threonate 667 mg, according to the retained record examined 2026-09-13; the label date is 2022-09-22.

The barcode is retained as an identifier, not as proof of a retail match. A registry version count records the number held; it does not reveal what changed. The label date, registry snapshot and price-observation date describe different events.