Corrected calcium calculator
Correct your total calcium for your albumin using the standard Payne formula. Because roughly 40% of blood calcium is bound to albumin, a low albumin makes total calcium read falsely low — this adjusts for it, in mg/dL or mmol/L.
Your privacy: this calculator runs entirely in your browser — nothing you type is sent anywhere. It's the same on-device principle Quanome is built on.
Educational reference only — not medical advice. The albumin correction is an estimate; when it matters, a directly measured ionised calcium is the gold standard. Reference ranges vary by lab — interpret with a clinician.
## What corrected calcium numbers mean
| Corrected calcium | Category |
| --- | --- |
| < 8.6 mg/dL (< 2.15 mmol/L) | Low (hypocalcaemia) |
| 8.6–10.2 mg/dL (2.15–2.55 mmol/L) | Normal |
| > 10.2 mg/dL (> 2.55 mmol/L) | High (hypercalcaemia) |
These are the same bands used for total calcium, and they vary a little between labs. A corrected value only tells you whether a low or high total calcium is likely *real* or just an albumin effect — it isn't a diagnosis on its own.
## The formula
**Payne formula (the standard albumin correction):**
- **mg/dL:** corrected calcium = total calcium + 0.8 × (4.0 − albumin g/dL)
- **SI (mmol/L):** corrected calcium = total calcium + 0.02 × (40 − albumin g/L)
It assumes a normal albumin of 4.0 g/dL (40 g/L) and shifts calcium up by 0.8 mg/dL for every 1 g/dL that albumin is below normal. If albumin is normal, the correction is zero and corrected calcium equals the measured value. The formula can over- or under-correct at very low albumin or in kidney disease, where a **directly measured ionised calcium** is more reliable.
## The rest of your metabolic panel
Calcium and albumin sit on the same comprehensive metabolic panel (CMP):
- **Albumin** — the protein doing the correction; see [what your albumin & the metabolic panel mean](/blog/albumin-alp-metabolic-panel-explained/).
- **Albumin/globulin ratio** — another way albumin is read; see [what your albumin/globulin ratio means](/blog/what-your-albumin-globulin-ratio-means/).
- Working in different units? The [mmol/L ↔ mg/dL converter](/tools/mmol-mg-dl-converter/) switches lipids and glucose between systems (note: calcium uses its own conversion, ~4 mg/dL = 1 mmol/L).
## Track your labs over time — privately
A single calcium is a snapshot; the value is in the **trend**. [Quanome](/) pulls your labs, Apple Health, and even your DNA into one private timeline on your device — parsed locally, never uploaded — with an AI coach that reads your metabolic panel in whichever units you use.
Track your labs over time, privately
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