Magnesium Intake Calculator
Daily magnesium mg vs RDA from foods plus supplement.
What it does
Magnesium hides in nuts, greens, and beans in uneven chunks. An ounce of almonds carries 80 mg while half a cup of cooked spinach carries 78, against RDAs of 400-420 mg for men and 310-320 for women. Two handfuls plus greens still leave gaps most days.
The tool above sums four lines against the RDA. Enter nuts, greens, other foods, and supplement milligrams, pick the age-sex RDA, and it prints total, target, gap, and percent. Defaults total 232 mg against 420: 188 mg short at 55.2 %.
NIH tables supply every constant. Its professional sheet sets RDA rows with foods at almonds 80, spinach 78, cashews 74, and black beans 60, while the consumer sheet confirms the 400/420 and 310/320 ladders. The National Academies IOM report stands behind the RDAs with a 350 mg supplemental upper limit.
Gaps close from food first. Beans, whole grains, and nuts stack steadily without pills, and split supplement doses absorb better than single megadoses. Laxative effects and drug interactions make higher doses a clinician conversation.
How to use
- Enter nuts mg (almonds 80/oz).
- Enter greens mg (spinach 78).
- Enter other food and supplement mg.
- Pick the RDA for age and sex.
- Read total first, then the gap.
- Close gaps with food first.
Formula
- nuts
- Mg from nuts and seeds.
- rest
- Mg from greens, beans, other foods, pills.
- RDA
- 310/320 women, 400/420 men.
RDA and food mg follow NIH ODS professional and consumer sheets with the IOM 1997 report behind them.
Worked example
Example: 232 mg vs 420 RDA
Defaults: nuts 154, greens 78, RDA 420.
- Inputs: nuts 154 mg (almonds 80 + cashews 74), greens 78, RDA 420 (man 35).
- Total: 154 + 78 = 232 mg.
- Gap: 420 minus 232 = 188 mg short.
- Share: 232 / 420 x 100 = 55.2 %.
- Tool shows 232 mg, 420 mg RDA, 188 mg short.
Reference table
| Item | mg | Note |
|---|---|---|
| Men 19-30 RDA | 400 | Baseline |
| Men 31+ RDA | 420 | Higher need |
| Women 19-30 RDA | 310 | Baseline |
| Women 31+ RDA | 320 | Higher need |
| Almonds 1 oz | 80 | Top nut |
| Spinach 1/2 cup | 78 | Top green |
Limits
- Planning math only. Absorption varies.
- Food mg are averages; brands differ.
- Upper limits need a clinician.
- Conditions adjust needs.
Common mistakes
- Counting one food and ignoring the rest.
- Megadosing past the 350 supplemental UL.
- Skipping the percent-of-RDA check.
- Treating the RDA as a ceiling.
- Ignoring drug interactions.
Try it yourself
Quick checks. Answers sit tucked under each question.
Nuts 80, other 60, RDA 310?
Total 80 + 0 + 60 + 0 = 140. Gap 310 minus 140 = 170 mg short.
Greens 156, other 60, RDA 400?
Total 0 + 156 + 60 + 0 = 216. Gap 400 minus 216 = 184 mg short.
Questions
How is the gap figured?
Sum food and supplement mg against the RDA. Here 232 vs 420 leaves 188 mg short.
What is the magnesium RDA?
Men 19-30: 400. Men 31+: 420. Women 19-30: 310. Women 31+: 320.
How much magnesium per food?
Almonds 80/oz, spinach 78/half-cup, cashews 74/oz, black beans 60/half-cup.
Can I split food groups?
Yes. Enter nuts, greens, other foods, and supplement lines separately.
Food or pills?
Food first per NIH, then supplements to close gaps. Supplemental UL runs 350 mg for adults.
Can I overdo magnesium?
Yes. Laxative effects and drug interactions need a clinician past food amounts.
Sources
- NIH ODS: Magnesium Professional Sheet (RDA, foods)
- NIH ODS: Magnesium Consumer Sheet (RDA ladder)
- National Academies: DRI Calcium/Magnesium Report (RDA values)