Identify vitamin and mineral deficiencies by comparing your daily intake to RDA targets. Find gaps and get food source recommendations.
Micronutrient deficiencies are surprisingly common, even in well-fed populations. Studies show that over 90% of Americans fall short of the RDA for at least one essential vitamin or mineral. The most common gaps include vitamin D (42% deficient), vitamin E (>90%), magnesium (~50%), calcium (~40%), and potassium (~97%).
This calculator helps you identify YOUR specific nutrient gaps by comparing your estimated daily intake against the Recommended Dietary Allowance (RDA) or Adequate Intake (AI) for your age and sex. It highlights which nutrients are critically low, which are adequate, and which might benefit from dietary adjustments or supplementation.
Rather than guessing which supplements to take, use this tool to find your actual gaps first. You may discover you're already meeting most needs through food, or you may uncover deficiencies you didn't expect. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation.
Blind supplementation wastes money and can cause harm (excess vitamin A, iron, or calcium can be toxic). This tool identifies your specific gaps so you can target exactly what you need — whether through food choices or focused supplementation. It's particularly valuable for vegetarians, dieters, older adults, and athletes who are at higher risk of specific deficiencies.
Gap = RDA Target – Daily Intake Gap Percentage = (Gap ÷ RDA Target) × 100 Status Classification: • Critically Low: <50% of RDA • Below Target: 50–99% of RDA • Adequate: 100–200% of RDA • High: >200% of RDA (check upper limits)
Result: 3 gaps found: Vitamin D (40%), Calcium (46%), Potassium (43%)
For a 31–50 year old female: Vitamin D intake of 8 mcg vs RDA of 15 mcg = 53% (Below Target). Calcium 600 mg vs RDA 1,000 mg = 60% (Below Target). Potassium 2,000 mg vs AI 2,600 mg = 77% (Below Target). Iron 12 mg vs RDA 18 mg = 67% (Below Target). Vitamin C 70 mg vs RDA 75 mg = 93% (Below Target, but close). These are common gaps for women.
Women of reproductive age: iron (due to menstruation), folate (critical before pregnancy), calcium (lower dairy intake). Older adults: vitamin D (reduced skin synthesis), B12 (reduced stomach acid absorption), calcium. Vegetarians/vegans: B12 (no plant sources), iron (lower bioavailability), zinc, omega-3. Athletes: iron (increased losses), magnesium (sweat losses), vitamin D (if indoor training). Dieters: nearly all micronutrients due to reduced food intake.
Fatigue can indicate iron, B12, vitamin D, or magnesium deficiency. Muscle cramps suggest magnesium or potassium. Frequent illness may indicate vitamin C, D, or zinc deficiency. Hair loss can be linked to iron, zinc, or biotin deficiency. Bone pain suggests vitamin D deficiency. Mouth sores can indicate B vitamins. These symptoms overlap with many conditions, so blood testing is needed for diagnosis.
Not all nutrients are equally absorbed. Heme iron (from meat) is absorbed at 15–35%, while non-heme iron (plants) is absorbed at 2–20%. Calcium from dairy is absorbed at ~30%, from spinach only ~5% (due to oxalates). Vitamin C enhances iron absorption, while coffee/tea inhibit it. Vitamin D aids calcium absorption. These interactions matter when planning how to close nutrient gaps.
RDA (Recommended Dietary Allowance) is the amount sufficient to meet the needs of 97–98% of healthy individuals, based on strong scientific evidence. AI (Adequate Intake) is used when insufficient evidence exists for an RDA — it's an estimated adequate amount based on observed intakes. Both are valid targets, but AI has more uncertainty. Potassium, for example, uses AI rather than RDA.
Extremely common. NHANES data shows 45% of the US population doesn't meet the EAR (Estimated Average Requirement) for vitamin A, 46% for vitamin C, 95% for vitamin D (from food alone), 97% for potassium, and 52% for magnesium. Dieting and restricting calories makes these gaps worse since there's less food to provide micronutrients.
Yes. Fat-soluble vitamins (A, D, E, K) accumulate in body fat and can reach toxic levels. Excess vitamin A causes liver damage; excess iron can cause organ damage. The Tolerable Upper Intake Level (UL) is the maximum daily amount unlikely to cause harm. Most people won't exceed ULs from food alone, but supplements can push you over.
A multivitamin can serve as "insurance" for common gaps, but it's not a replacement for a balanced diet. Many multivitamins contain inadequate amounts of the most-needed nutrients (vitamin D, magnesium, potassium) while providing excess of others. Targeted supplementation based on identified gaps is more effective and cost-efficient.
Vitamin D (very few food sources; mostly from sun exposure), potassium (requires very high vegetable/fruit intake), magnesium (soil depletion has reduced content in foods), and omega-3 fatty acids (requires regular fatty fish consumption). Vitamin B12 is impossible to get on a strict vegan diet without supplementation.
Significantly. Below 1,500 kcal/day, it becomes very difficult to meet all micronutrient needs from food alone. Below 1,200 kcal, deficiencies are nearly guaranteed without supplementation. This is why crash diets and very low-calorie diets often cause fatigue, hair loss, and weakened immunity — common signs of micronutrient deficiencies.