Blood Donor Calculator
Check blood type compatibility for donation and transfusion
Check Blood Compatibility
Select your blood type including Rh factor (+ or -)
Compatibility Results
You can donate blood to:
How it works
Blood compatibility depends on ABO antigens (A, B, AB, O) and Rh factor (+/-). You can only receive blood from compatible donors to avoid dangerous reactions.
⚠️ Medical Disclaimer: This calculator provides general compatibility information for educational purposes. Actual blood transfusion decisions require professional medical evaluation and cross-matching tests.
Blood Compatibility Charts
Blood Donation Compatibility
| Donor ↓ / Recipient → | O+ | O- | A+ | A- | B+ | B- | AB+ | AB- |
|---|---|---|---|---|---|---|---|---|
| O+ | ✓ | ✗ | ✓ | ✗ | ✓ | ✗ | ✓ | ✗ |
| O- | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| A+ | ✗ | ✗ | ✓ | ✗ | ✗ | ✗ | ✓ | ✗ |
| A- | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ | ✓ | ✓ |
| B+ | ✗ | ✗ | ✗ | ✗ | ✓ | ✗ | ✓ | ✗ |
| B- | ✗ | ✗ | ✗ | ✗ | ✓ | ✓ | ✓ | ✓ |
| AB+ | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ | ✓ | ✗ |
| AB- | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ | ✓ | ✓ |
Plasma Donation Compatibility
| Donor ↓ / Recipient → | O | A | B | AB |
|---|---|---|---|---|
| O | ✓ | ✓ | ✓ | ✓ |
| A | ✗ | ✓ | ✗ | ✓ |
| B | ✗ | ✗ | ✓ | ✓ |
| AB | ✗ | ✗ | ✗ | ✓ |
Universal Types
Blood
O-: Universal donor
AB+: Universal recipient
Plasma
AB: Universal donor
O: Universal recipient
Blood Type Facts
Antigens & Antibodies
Blood type is determined by proteins (antigens) on red blood cell surfaces and corresponding antibodies in plasma.
Rh Factor
Rh+ blood contains the Rh protein, Rh- does not. This affects blood donation compatibility.
Agglutination
Mixing incompatible blood types causes clumping (agglutination), which can be life-threatening.
Understanding Blood Type Compatibility
Blood Type System
Human blood is classified into four main groups based on the presence or absence of specific antigens on red blood cell surfaces: A, B, AB, and O. Each group also has a positive (+) or negative (-) Rh factor, creating eight distinct blood types.
Type A
Has A antigens, makes B antibodies
Type B
Has B antigens, makes A antibodies
Type AB
Has both A and B antigens, makes no antibodies
Type O
Has no antigens, makes both A and B antibodies
Compatibility Rules
Safe Transfusion
Blood can only be transfused if the recipient doesn't have antibodies against the donor's antigens. This prevents dangerous immune reactions.
Rh Factor Rules
Rh- individuals can receive both Rh+ and Rh- blood, but Rh+ individuals should ideally receive Rh+ blood to avoid sensitization.
Plasma vs Blood
Plasma compatibility follows opposite rules to blood compatibility because plasma contains antibodies rather than antigens. Rh factor doesn't matter for plasma.
Emergency Situations
In life-threatening emergencies, O- blood (universal donor) may be used when the patient's blood type is unknown, but cross-matching is always preferred.
Frequently Asked Questions
What happens if incompatible blood is transfused?
Incompatible blood causes agglutination (clumping), which can block blood vessels and cause organ failure, kidney damage, or death.
Why is O- called the universal donor?
O- blood has no A, B, or Rh antigens, so it won't react with any recipient's antibodies, making it safe for emergency transfusions.
Can I receive my own blood type?
Yes, you can always safely receive your own blood type, plus compatible donor types as shown in the compatibility chart.
How is blood compatibility tested?
Cross-matching tests mix donor blood with recipient serum to check for reactions. Type and screen tests identify blood type and check for antibodies.
Are there other blood group systems besides ABO and Rh?
Yes, there are over 300 blood group systems, but ABO and Rh are the most clinically important for transfusion compatibility.