Basophil count optimal range and reference range
Compiled by Alina Radu, founder of Sera, from the published sources below · Last reviewed November 9, 2026
Sera's bands for Basophil count:
- Optimal 0.02 – 0.08 ×10⁹/L (0.02 – 0.08 ×10³/μL); sufficient 0.01 – 0.1 ×10⁹/L (0.01 – 0.1 ×10³/μL); out of range above 0.1 ×10⁹/L.
Evidence grade: Published reference interval. A band that primarily reflects a published adult laboratory or population reference interval. It is not necessarily applicable to every assay or laboratory.
All units
| Unit | Optimal | Sufficient | Out of range |
|---|---|---|---|
| ×10⁹/L | 0.02 – 0.08 | 0.01 – 0.1 | above 0.1 |
| ×10³/μL | 0.02 – 0.08 | 0.01 – 0.1 | above 0.1 |
| K/μL | 0.02 – 0.08 | 0.01 – 0.1 | above 0.1 |
| /mm³ | 20 – 80 | 10 – 100 | above 100 |
| x E9/L | 0.02 – 0.08 | 0.01 – 0.1 | above 0.1 |
Bounded on the high side only — a low result is not treated as out of range. Most laboratories start the basophil interval at zero and no source defines a low basophil threshold.
What the evidence says
The acceptable band ends at 0.1, the adult upper reference limit at most laboratories checked; one NHS laboratory uses 0.2. Basophils are normally so few that a low count has no accepted meaning, and most laboratories start the interval at zero. The optimal ceiling of 0.08 has no published source. The count is interpreted mainly when it is persistently raised, alongside the total white cell count, and a trend matters more than a single value.
Sources
- Haematology reference ranges — Gloucestershire Hospitals NHS Foundation Trust, 2026 · Laboratory / reference-interval sourceAdult basophils 0.02 to 0.10 ×10⁹/L. Matches Sera's sufficient upper edge of 0.1; its lower limit of 0.02 equals Sera's optimal lower edge.
- FBC — University Hospitals Sussex NHS Foundation Trust, Pathology, 2022 · Laboratory / reference-interval sourceAdult basophils 0 to 0.1 ×10⁹/L. Matches Sera's sufficient upper edge; the lower limit is zero.
- Full blood count (FBC) — Black Country Pathology Services (NHS), 2026 · Laboratory / reference-interval sourceAdult basophils 0 to 0.1 ×10⁹/L. Matches Sera's sufficient upper edge; the lower limit is zero. The page shows no review date; 2026 is the footer year.
- AUTO DIFF (test catalog entry) — MHCC Laboratory, test catalog powered by Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdult absolute basophils 0.0 to 0.1 ×10³/μL. Matches Sera's sufficient upper edge; the lower limit is zero. The page shows no review date; 2026 is the copyright year.
What Basophils # measures
The number of basophils, the rarest white blood cells, which take part in inflammation and allergic reactions.
Usually very low. A rise can point to allergies or long-term inflammation.
Related blood cell health markers
- RBC # (Red Blood Cell Count)
- Hemoglobin (HGB)
- Hematocrit (HCT)
- Mean Corpuscular Volume (MCV)
- Mean Corpuscular Hemoglobin (MCH)
- Mean Corpuscular Hemoglobin Concentration (MCHC)
- RDW (Red Cell Distribution Width)
- WBC # (White Blood Cell Count)
- Neutrophils #
- Lymphocytes #
- Monocytes #
- Eosinophils #
- Neutrophils %
- Lymphocytes %
- Monocytes %
- Eosinophils %
- Basophils %
- Immature Granulocytes %
- Platelets (Thrombocytes)
- PCT (Plateletcrit)
- Reticulocytes (Absolute)
- Reticulocytes (%)
- Ferritin
- Iron (Serum)
- Transferrin
- TIBC (Total Iron Binding Capacity)
- Transferrin Saturation
- UIBC (Unsaturated Iron Binding Capacity)