Daily Vitamin C Intake Target Calculator
**Vitamin C (L-ascorbic acid)** is a water-soluble essential nutrient — humans (and a handful of other primates) lack L-gulonolactone oxidase, so we cannot synthesise it and must obtain it from food. It is central to *collagen synthesis* (blood vessels, skin, bone, gums), *iron absorption* (reducing non-heme Fe³⁺ to absorbable Fe²⁺), *immune-cell function*, *neurotransmitter synthesis* (dopamine, noradrenaline) and serves as a powerful *antioxidant*. This tool looks up the US NIH Dietary Reference Intake (DRI, 2000) RDA table by age, sex, life stage and smoking status, returns your daily mg target, converts it into common food portions and shows the safe Tolerable Upper Intake Level (UL).
Enter a realistic age and matching life stage.
Daily vitamin C target
90 mg / day
19+ yr, male
Includes the +{mg} mg smoker adjustment
Tolerable UL: 2000 mg / day
Equivalent food servings (any one)
- 1.3 medium orange (~70 mg each)
- 0.5 cup raw red bell pepper (~190 mg per cup)
- 0.9 cup cooked broccoli (~101 mg per cup)
- 1.0 cup fresh strawberries (~89 mg per cup)
- 0.7 cup fresh-squeezed orange juice 240 mL (~124 mg per cup)
% of target
56%
Notes
- Targets follow the US IOM (2000) / NIH Dietary Reference Intake (DRI) tables. EFSA adult PRI is slightly higher (males 110, females 95 mg) and WHO / FAO recommends 45 mg. The NIH figures are the most widely used in North America, the UK and most of Asia.
- Vitamin C (ascorbic acid) is a water-soluble antioxidant essential to collagen synthesis (skin, blood vessels, wound healing), iron absorption (Fe³⁺ → Fe²⁺), immune-cell function and the synthesis of neurotransmitters (dopamine, noradrenaline). Severe deficiency causes scurvy — bleeding gums, poor wound healing, bruising.
- Adult UL is 2 000 mg / day; over-dosing mainly causes osmotic diarrhoea and abdominal cramping, and modestly raises calcium-oxalate kidney-stone risk (people with a stone history should keep supplemental vitamin C ≤ 200 mg / day). Vitamin C is destroyed by heat, prolonged storage, water-soaking and air exposure — eat fresh produce promptly.
Formula
target_mg = lookup(ageBand, sex, lifeStage) + (smoker && age ≥ 14 ? 35 : 0) Age bands (mg / day, NIH ODS Vitamin C Fact Sheet): 0–6 mo : AI 40 7–12 mo : AI 50 1–3 yr : RDA 15 4–8 yr : RDA 25 9–13 yr : RDA 45 14–18 yr male : 75 female: 65 19+ yr male : 90 female: 75 Pregnancy 14–18 : 80 Pregnancy 19+: 85 Lactation 14–18 : 115 Lactation 19+: 120 UL (mg / day): 1–3:400, 4–8:650, 9–13:1200, 14–18:1800, ≥19:2000
- · **Source**: US Institute of Medicine, "Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids" (2000); NIH Office of Dietary Supplements, *Vitamin C Fact Sheet for Health Professionals* — https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/. EFSA 2013 PRI is higher (males 110, females 95 mg); WHO / FAO 2004 recommends 45 mg.
- · **Smoker +35 mg / day**: the IOM notes that smokers have ~30 % lower plasma vitamin C and elevated oxidative / metabolic turnover; people with regular second-hand-smoke exposure should also add the +35 mg. This tool applies the bump only to active smokers; passive-smoke households can mirror it manually.
- · **Iron-absorption synergy**: 50–100 mg of vitamin C taken with non-heme iron (spinach, beans, fortified cereal) raises iron absorption ~3-fold. Particularly useful for vegetarians, pregnant people and those with heavy menstrual losses.
- · **Food vs. supplements**: dietary sources also deliver flavonoids, fibre and other antioxidants. Supplemental doses above ~200 mg / day hit a saturation ceiling — absorption efficiency drops sharply and the excess is excreted in urine; little extra benefit, little harm short of the UL.
- · **Storage losses**: vitamin C is degraded by heat (> 70 °C), water-soaking, prolonged storage and air contact — cut bell peppers lose ~30 % over 24 h; cooked broccoli loses ~50 % (steamed > microwaved > boiled). Eat fresh, eat soon, cut just before serving.
- · **Overdose risks**: UL is 2 000 mg / day for adults; over-dosing mainly causes diarrhoea, nausea and osmotic cramping. People with a history of calcium-oxalate kidney stones should keep supplements ≤ 200 mg / day. Hereditary hemochromatosis patients should avoid large doses (boosts iron over-absorption).
Frequently asked
Doesn't one orange cover my full day's vitamin C — do I still need vegetables?
**Hitting the RDA is not the same as being optimised.** A medium orange (~70 mg) already covers most of the 75 / 90 mg RDA. **But**: (1) **smokers add +35 mg**, so 110–125 mg is needed and one orange falls short; (2) **illness, wounds, heavy exercise** raise oxidative stress; observational data support ~200 mg / day; (3) the **RDA is the minimum to prevent scurvy**, not the dose to *saturate plasma* (≥ 50 µmol/L), which generally needs 100–200 mg; (4) vitamin C **half-life is 8–40 h** — split intake across meals absorbs better than one big dose. **Practical advice**: put one serving of fresh produce on each plate (orange, red pepper, broccoli, strawberries, kiwi). You will naturally reach 150–300 mg / day, well above the RDA but well below the UL, while also getting fibre, flavonoids, folate and potassium.
I take a 1 000 mg vitamin C supplement to prevent colds — does that actually work?
**Cochrane 2013 meta-analysis (n > 11 000)** found: (1) for the general population, ≥ 200 mg / day vitamin C does **not** reduce cold incidence; (2) it **shortens** cold duration by ~8 % in adults and ~14 % in children (a 7-day cold becomes ~6.4 days — modest); (3) for **heavy-exertion or extreme-cold groups** (marathon runners, soldiers, cross-country skiers) 200–1 000 mg / day cut cold incidence ~50 %. **Bottom line**: no prevention benefit for sedentary people; meaningful benefit for high-stress athletic / extreme-environment groups. **Safety**: 1 000 mg is still well below the 2 000 mg UL, but absorption efficiency falls with dose (~75 % at 500 mg, ~50 % at 1 500 mg, much lower past that). Splitting into 2 × 500 mg morning and evening absorbs better than 1 × 1 000 mg.
How much vitamin C survives cooking? My household tends to over-boil vegetables.
**Prolonged boiling is the worst way to handle vitamin C**, because it is both *water-soluble* and *heat-labile*. **Typical retention vs raw**: (1) **raw / fresh juice**: 95–100 %; (2) **brief steam 3–5 min**: 80–90 %; (3) **microwave with little water**: 70–85 %; (4) **stir-fry 2 min**: 70–80 %; (5) **boil 10 min**: 30–50 % (much leaches into the water); (6) **refrigerated 1 week**: 60–80 %; (7) **canned / cooked-then-frozen**: 50–70 %. **How to preserve more**: (a) cut into large pieces (less surface); (b) cut just before cooking; (c) prefer steam, microwave or stir-fry over boiling; (d) drink the cooking water (most vitamin C is in there); (e) stop *just* when tender. A 100 g serving of raw red pepper has ~127 mg; after 10 min boiling it has ~50 mg — still useful but you need roughly double the portion for the same intake.
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Enter age, sex and life stage; the tool returns the daily folate target in µg DFE from the NIH ODS Folate Fact Sheet RDA (adults 400, pregnancy 600, lactation 500, supplement UL 1000 µg / day) — the B-vitamin central to cell division, red-blood-cell formation and the prevention of fetal neural-tube defects.
Workout Rest Between Sets Calculator
Enter your training goal (maximal strength, hypertrophy, muscular endurance, power) and load intensity (% 1RM); the tool returns evidence-based rest-interval seconds between sets and the matching set / rep ranges, per NSCA Essentials of Strength Training (4th ed.) and ACSM guidelines.
Daily Vitamin B12 Intake Target Calculator
Look up your daily vitamin B12 RDA (μg/day) by age, sex and pregnancy / lactation status using NIH ODS values, with B12 amounts in common foods and supplementation notes for vegetarians and vegans.
Daily Iodine Intake Target Calculator
Look up your daily iodine RDA (μg/day) by age, sex and pregnancy / lactation status using NIH ODS values, with iodine content in iodised salt, seafood and common foods — guarding against deficiency (goitre) and excess (thyroid dysfunction).
Daily Vitamin A Intake Target Calculator
Look up your daily vitamin A RDA (μg RAE/day) and tolerable upper intake (UL) by age, sex and pregnancy / lactation status using NIH ODS values; converts retinol and β-carotene to RAE so you can avoid deficiency (night blindness) and retinol overdose.
HRV RMSSD Calculator (Heart Rate Variability)
Paste a list of RR intervals (in ms, comma- / space- / newline-separated); the tool returns RMSSD = √(mean((RR_{i+1} − RR_i)²)), SDNN, mean heart rate, and an interpretation following the 1996 Task Force HRV standards — handy for sanity-checking HRV figures from a Garmin, Apple Watch or Polar device.
Running Shoe Replacement Distance Calculator
Enter the shoe type (max-cushion, daily trainer, racing flat and more), runner weight tier and miles already logged; the tool uses the 300–500 mile sports-medicine wear-out range to return the miles remaining and a months-of-use estimate at your current cadence — handy for avoiding knee pain and plantar fasciitis from worn midsoles.
Caffeine Half-Life Decay Calculator
Caffeine's half-life averages about 5 hours — a 200 mg morning coffee still leaves ~100 mg in your blood at 5 pm and ~50 mg by 11 pm. Enter the dose and time taken to see exactly how much is still circulating when you try to sleep.
BMI Prime Calculator
BMI Prime = BMI ÷ 25 — expresses any BMI as a fraction of the normal-weight upper limit, so 1.00 means right at the cap and 1.20 means 20 % above it. Enter height and weight to read it instantly.
Spherical Equivalent (SE) Eye Prescription Calculator
Spherical equivalent SE = Sphere + (Cylinder ÷ 2) collapses a cylindrical (astigmatism) prescription into a single spherical power — routinely used for ordering contact lenses, refractive-surgery screening, and basic vision reports. Also returns the vertex-compensated corneal-plane power for high Rx.
Pregnancy Weight Gain Calculator (IOM Guidelines)
Enter pre-pregnancy height and weight (for BMI), gestational week and current weight; the tool returns the recommended total weight-gain range and weekly rate for singleton or twins based on the Institute of Medicine (IOM/NAM 2009) guidelines, comparing to actual gain.
Life Expectancy by Current Age Calculator
Enter current age and sex; using the WHO Global Health Observatory period life table, the tool estimates remaining life expectancy and projected age at death assuming present-day mortality.
Sunscreen Amount & SPF Protection Time Calculator
Using the dermatology 2 mg/cm² standard, work out how many grams of sunscreen (≈ the "shot-glass rule") you need for full body or each zone, then estimate reapplication interval from the classic "SPF × natural burn time" formula.
Hike Difficulty (Petzoldt Energy Miles) Calculator
Enter trail distance, elevation gain and walking pace; using outdoor educator Paul Petzoldt's "energy miles" rule (+2 miles per 1,000 ft gain), the tool returns effective distance, estimated time and a difficulty rating.
Marathon Fueling Gels Calculator
Enter race distance, projected finish time and carb intake target (g/h); based on the 30–90 g/h sports nutrition range, returns how many gels and at what spacing.
Cooper 12-Minute Run VO₂max Calculator
Enter your 12-minute run distance (m or mi), age and sex; the tool estimates VO₂max via Cooper's 1968 JAMA formula and maps it to a six-band age/sex fitness classification.
Max Heart Rate (HRmax) Formula Comparison Calculator
Enter age (and optional resting HR); compare HRmax estimates from Fox (220−age), Tanaka, Gellish and the Nes / HUNT3 formula side-by-side, plus Karvonen training-zone bpm ranges.
Bone Density T-Score / Z-Score Interpretation Calculator
Enter DEXA-scan T-score (and optional Z-score); classifies as normal / osteopenia / osteoporosis per WHO 1994 + ISCD 2019 criteria and shows relative fracture-risk multiplier.
Cycling FTP (Functional Threshold Power) Estimator + Training Zones
Enter your best 20-minute average power (watts) to get your FTP (= 20-min × 0.95) and the seven Coggan training zones (Z1 Recovery through Z7 Neuromuscular).
WHO Oral Rehydration Solution (ORS) Recipe Calculator
Enter the total water volume (ml) — get the grams of salt, glucose (or substitute sucrose) and optional potassium chloride needed for a WHO/UNICEF low-osmolarity ORS, the standard rehydration recipe for diarrhoea worldwide.
Reading Glasses (Near-Add) Diopter by Age Calculator
Enter your age and habitual reading distance — get a quick estimate of the near-add power (+0.50 to +3.00 D) for off-the-shelf reading glasses, based on the Hofstetter 1944 accommodation formula and standard optometric guidance.