Blood Donation Eligibility Calculator
Check blood donation eligibility from age, weight, health status, and recent activities.
Covers the 110 lb minimum, 56-day interval, and travel restrictions.
Blood donation eligibility is determined by a set of criteria established by organizations such as the American Red Cross, AABB, and equivalent bodies worldwide. These criteria exist to protect both the donor and the recipient. This calculator is a general pre-screening. Final eligibility is always decided by blood bank staff on the day.
Basic Requirements for Whole Blood Donation:
| Criteria | Requirement |
|---|---|
| Age | 17+ years (16 with parental consent in some regions) |
| Weight | At least 110 lbs (50 kg) |
| Hemoglobin | Female: 12.5 g/dL minimum. Male: 13.0 g/dL minimum |
| Health | Generally healthy, feeling well on day of donation |
| Time since last donation | Whole blood: 56 days (8 weeks). Platelets: 7 days. Plasma: 28 days |
Common Temporary Deferrals:
- Tattoo or piercing: 3–12 months depending on location and regulation
- Travel to malaria-endemic areas: 3–12 months after return
- Recent illness (cold, flu): Until fully recovered, typically 7–14 days
- Antibiotics: Until course is completed and infection is resolved
- Surgery: 6–12 months depending on type
- Pregnancy: 6 weeks after delivery
- Vaccination: Varies by vaccine type (0–14 days for most, 2 weeks for live vaccines)
Donation Types and Frequency:
| Type | Frequency | Duration | Volume |
|---|---|---|---|
| Whole blood | Every 56 days | 8–10 minutes | 1 pint (~470 mL) |
| Platelets (apheresis) | Every 7 days (max 24/year) | 1.5–2.5 hours | Platelets only |
| Plasma | Every 28 days | 1–1.5 hours | Plasma only |
| Double red cells | Every 112 days | 30 minutes | 2 units red cells |
Weight and Blood Volume: Total blood volume runs at roughly 70 mL per kilogram of body weight, which works out at about one pint per 14 lbs of you. The 110 lb (50 kg) minimum exists so that a single pint stays a safe share of the total: at exactly the minimum weight, 470 mL out of about 3,500 mL is 13%. At 180 lb it is closer to 8%, which is why larger donors tolerate it more easily and why the floor is set where it is.
After Donation Tips: Drink extra fluids for the next 24 to 48 hours and skip heavy lifting or hard exercise for a day. Eat iron-rich foods, and pair them with vitamin C, which meaningfully improves absorption of the iron in plants. Fluid volume is back within 24 hours, but red cells take 4 to 6 weeks and iron stores can take longer still. That gap is the whole reason for the 56-day interval.
One Donation Can Save Up to Three Lives: Whole blood is separated into red cells, platelets and plasma, and each component can go to a different patient. Regular donors carry the supply, and demand never pauses.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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