Next-date calculator
Country × donation type × sex × last date → the exact next-eligible date on the ring.
A free, offline tool for blood donors
How to know exactly when you can donate blood again
The week after you give blood, one question comes up: “when can I donate again?” The honest answer is a single date. donorbook computes it on your own device — from cited national rules — and never sends your health information anywhere.
14
days to go
The problem
Search “when can I donate blood again” and you get everything but a date.
Most results are a vague blog post, or a lead-generation page that wants your name, phone number and medical history before it tells you anything. The real answer is arithmetic anyone can do — last donation + your country's interval — and it should not cost you your privacy.
what you usually get
- ✕ “It depends” blog posts with no date
- ✕ Forms that harvest your details first
- ✕ Rules for the wrong country
- ✕ No sense of which rule applies to you
what you actually need
- ✓ One exact next-eligible date
- ✓ The cited rule behind it
- ✓ A private place to log donations
- ✓ Nothing sent to anyone, ever
How it works
Your last donation, plus one published interval, becomes an exact date.
Pick your country and donation type. donorbook reads the interval straight from its cited ruleset and adds it to your last-donation date. The eligibility ring then fills up as the wait elapses — a live countdown to the day you can give again.
last donation
01 Jan
+
NBTC interval (male)
90 days
=
next eligible
01 Apr
Calendar arithmetic that clamps month-ends and handles leap years — proven to the day in the app's tests.
29
days to go
The ring is the motif — the same countdown carried into the icon and the OG card.
Every verdict is cited
No number appears without the rule it came from.
donorbook never authors a rule from memory. Each interval, age floor and deferral is quoted verbatim from a named authority — NBTC India, the American Red Cross, UK NHSBT — with a source link and the date it was last verified. And any medication or detailed-history question resolves to a single honest answer: ask the blood bank.
Likely eligible
Whole blood, every 56 days.
American Red Cross · verified 2026-07-22
Deferred until 12 Aug
Tattoo in the last 3 months — wait to the resume date.
UK NHSBT · verified 2026-07-22
Ask the blood bank
Started a new medication — never computed here.
Policy by design · not medical advice
Privacy you can verify
The browser itself blocks any send. It is not a promise — it is enforced.
donorbook ships one line in its security policy: connect-src 'none'.
That instructs your browser to refuse every network request the page could make — fetch, upload,
analytics, all of it. Your donation history stays in this browser's storage and physically cannot leave.
your device
logbook
blood group
next date
the internet
Every packet that tries to leave is stopped at the browser. Offline by construction — it even works with no signal.
A quick tour
Five things donorbook does — all on your device.
Guided pre-check
Age, weight, haemoglobin and a fixed set of deferrals → a verdict with its cited rule.
Private logbook
Date, type, centre, notes — stored only in your browser, with a yearly count vs the cap.
Group compatibility
Any of the 8 groups → donate-to / receive-from, for red cells or plasma.
Exports as the handoff
CSV of the logbook, a downloadable .ics reminder, and a printable wallet donor card.
Full sources panel
Every rule with its authority, verbatim quote, link and last-verified date.
Find your next-eligible date now.
Free, offline, no account. It opens in your browser and computes everything on your device.
Open donorbook →No install. No sign-up. Nothing leaves your browser.