How Often Can You Donate Blood
Updated May 2026
Reference summary
Donation intervals exist to protect the donor from iron depletion and to allow each blood component to replenish before the next donation. The intervals differ by donation type and by jurisdiction. This page summarises the current US and UK rules. The donor centre will check your last donation date at each visit.
Quick reference table
| Donation type | US (Red Cross) | UK (NHSBT) |
|---|---|---|
| Whole blood | 56 days, max 6/year | 12 wk men / 16 wk women |
| Power Red | 112 days, max 3/year | Limited availability |
| Apheresis platelets | 7 days, max 24/year | 14-28 days, max 24/year |
| Apheresis plasma | 28 days | Limited availability since vCJD pause |
Sources: American Red Cross eligibility, NHSBT who can give blood.
Whole blood: 56 days (US) or 12-16 weeks (UK)
The minimum interval after a whole blood donation is set by how long the body takes to replenish red cell mass. Red blood cells have a lifespan of about 120 days; the body produces about 1 percent of its red cell mass per day. After a whole blood donation removes about 10 percent of total red cell mass, the body needs around 8 weeks (the US 56-day interval) to restore baseline.
Iron repletion lags red cell replenishment. The body uses about 200 mg of iron per donated unit, which must be replaced from dietary sources (or supplements). For donors with adequate iron intake (red meat, leafy greens, fortified foods), repletion typically completes within the donation interval. For donors with marginal intake, especially women in their reproductive years and frequent donors, repletion can take longer.
The longer UK interval (12 weeks for men, 16 weeks for women) was set after the 2017 INTERVAL trial compared shorter intervals to standard. The trial showed that shorter intervals do collect more units but at a cost of more deferrals for low haemoglobin and more donor iron deficiency. UK guidance reflects the conservative end of the evidence; US guidance reflects the more aggressive end.
Power Red: 112 days
Power Red apheresis collects two units of red cells per visit while returning plasma, platelets, and saline. The donor loses twice the red cell mass of a whole blood donation, so the interval is twice as long: 112 days, up to 3 times per year.
Eligibility for Power Red requires higher haemoglobin and weight thresholds than whole blood (typically 5'1" / 130 lb for women and 5'3" / 150 lb for men, with corresponding higher haemoglobin minima). The donor centre will check at each visit. The donor needs adequate iron stores to support the doubled red cell loss.
Power Red is a good fit for donors who want higher impact per visit and prefer longer intervals between visits. The total annual red cell contribution from a maximum-frequency Power Red donor (3 times a year, 6 units) is the same as a maximum-frequency whole blood donor (6 times a year, 6 units), but with half the visits.
Apheresis platelets: 7 days, max 24/year
Platelet apheresis returns red cells and plasma, removing only platelets. The donor's platelet count drops slightly after donation but recovers within a few days because platelet half-life is short (about 7 to 10 days) and the bone marrow continuously produces new platelets. The minimum interval of 7 days reflects this rapid recovery.
The annual cap of 24 visits exists to limit cumulative procedural exposure (citrate administration, venous access, time on the apheresis machine) rather than because of any specific platelet replenishment concern. The cap is identical in the US and UK.
Most regular platelet donors give every 2 weeks, not every week, balancing convenience with impact. UK NHSBT often schedules platelet donors at 14 to 28 day intervals rather than the 7-day minimum, partly to spread donor capacity across the schedule.
Apheresis plasma: 28 days
Plasma apheresis removes plasma and returns red cells and platelets. The donor loses plasma volume (replaced by saline during the procedure) and the protein content of the plasma (mostly albumin and immunoglobulins). The interval of 28 days allows protein replenishment.
US paid plasma centres allow more frequent donation (typically twice per week) under FDA regulations that apply to source plasma supplied to fractionation companies. The shorter intervals reflect different supply chains, different regulatory frameworks, and (controversially) different risk tolerances. Volunteer plasma donation in the US (American Red Cross) follows the 28-day standard.
UK plasma apheresis was paused following the 1990s vCJD concerns and reintroduced in 2021 for limited use. The UK plasma supply for FFP and immunoglobulin manufacturing was historically dependent on imported plasma, with a gradual return to UK-sourced plasma now under way.
Planning a regular donation schedule
Most regular whole blood donors give 3 to 4 times a year, slightly less than the maximum of 6 (US) or 4 (UK). The lower frequency allows generous iron repletion and reduces the risk of low-haemoglobin deferrals at the next visit. The Red Cross and NHSBT both publish iron-replacement guidance for donors who want to give close to the maximum frequency.
For platelet apheresis donors, the typical pattern is every 2 to 4 weeks, contributing 12 to 24 donations per year. This is a substantial commitment but produces an enormous impact: each apheresis donation supports a full adult therapeutic dose of platelets.
See our donation types page for the time and impact comparison across donation types, and our eligibility page for the wider deferrals that affect schedule.