What this calculator does
Different donation types deplete different things, so the waiting period between them varies considerably. Platelets regenerate within days; red cells take far longer, and a double red cell donation takes twice as long again.
The intervals run from 7 to 112 days. Platelets allow donation every 7 days, plasma every 28, whole blood every 56, and double red cells every 112.
The formula
The minimum interval for the selected donation type is added to the date of the last donation, giving the earliest eligible date and the days remaining until it.
| Term | Meaning |
|---|---|
| Whole blood | The standard donation, with a 56 day minimum interval. |
| Double red cells | An apheresis donation taking two units of red cells, requiring 112 days. |
| Apheresis | Donation where components are separated and the rest returned, allowing shorter intervals. |
The inputs explained
| Field | What to enter |
|---|---|
| Date of last donation | The date of your most recent donation. |
| Donation type | Which type of donation it was, which sets the interval. |
When to use it
Planning your next donation
Knowing the earliest date avoids a wasted trip.
Choosing a donation type
Platelet donors can give far more frequently than whole blood donors.
Scheduling around a drive
Checking eligibility before a blood drive saves being turned away.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How long between each type of donation?
The four donation types and their waiting periods.
| Donation type | Minimum interval used | Note |
|---|---|---|
| Platelets | 7 days | US Red Cross minimums; local blood services may set different intervals |
| Plasma | 28 days | US Red Cross minimums; local blood services may set different intervals |
| Whole blood | 56 days | US Red Cross minimums; local blood services may set different intervals |
| Double red cells | 112 days | US Red Cross minimums; local blood services may set different intervals |
Questions
Why can platelets be donated so often?
Because apheresis returns your red cells and plasma, taking only the platelets, and platelet counts recover within a few days. Whole blood removes red cells, which take considerably longer to replace.
Are these intervals the same everywhere?
No. These are US Red Cross minimums, and other countries differ: several set whole blood intervals at 12 or 16 weeks, and some apply different intervals by sex. Check your local blood service.
What else affects eligibility?
A great deal besides timing: haemoglobin level, recent travel, medications, tattoos, illness and more. The interval is a necessary condition rather than a sufficient one, and screening happens at every donation.
Why is there an interval at all?
To protect the donor. Replacing the iron in a whole blood donation takes months, and donating too frequently causes iron deficiency. The intervals exist to keep donors healthy rather than to ration supply.
For blood type inheritance, see the blood type calculator. For red cell indices, see the MCH and MCHC calculator.