What this calculator does
Next blood donation eligibility date works out earliest date you can donate again, from your last donation and the donation type. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaNext eligible date = last donation date + minimum interval (whole blood 56 days, double red cells 112 days, platelets 7 days, plasma 28 days)
The inputs explained
| Field | What to enter |
|---|---|
| Date of last donation | A calendar date. |
| Donation type | Choose from Whole blood (56 days), Double red cells (112 days), Platelets (7 days), Plasma (28 days). |
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 the answer changes with donation type
Every other input is held at the calculator’s starting values. Select any row to load that scenario.
How the answer changes with donation type
| Donation type | Next eligible date | Days until eligible | Minimum interval used |
|---|---|---|---|
| Whole blood (56 days) | 4 Sep 2026 | 26 days | 56 days |
| Double red cells (112 days) | 30 Oct 2026 | 82 days | 112 days |
| Platelets (7 days) | 17 Jul 2026 | Eligible now | 7 days |
| Plasma (28 days) | 7 Aug 2026 | Eligible now | 28 days |