Enter the calcium and phosphorus values into the calculator to determine the calcium/phosphorus ratio.

Calcium/Phosphorus Ratio Calculator

Enter your calcium and phosphorus to get the Ca:P ratio and see how it compares to healthy targets.

Ca:P Ratio
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Educational use only; not medical advice. This calculator compares dietary calcium and phosphorus amounts (e.g., mg per serving or mg/day) and is not for interpreting blood or urine lab results. Do not use it to diagnose, treat, or set supplement/medication doses. Discuss changes with a clinician or registered dietitian—especially if you have kidney disease, parathyroid/bone-mineral disorders, or take phosphate binders, calcium, or vitamin D. For general nutrition guidance, see the NIH Office of Dietary Supplements fact sheets for Calcium and Phosphorus.

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Calcium/Phosphorus Ratio Formula

The following formula is used to calculate the calcium/phosphorus ratio from calcium and phosphorus amounts.

R = \frac{Ca}{P}

Variables:

  • R is the calcium/phosphorus ratio
  • Ca is the amount of calcium (typically listed in mg on labels; the calculator can also convert from g)
  • P is the amount of phosphorus (typically listed in mg on labels; the calculator can also convert from g)

To calculate the calcium/phosphorus ratio, divide the amount of calcium by the amount of phosphorus.

What is the Calcium/Phosphorus Ratio?

The calcium-to-phosphorus (Ca/P) ratio is sometimes used as a rough way to compare dietary calcium and phosphorus amounts (for example, across foods, supplements, or a day’s total intake). In general, most nutrition guidance focuses on meeting recommended intakes for calcium and phosphorus rather than targeting one universal ratio, and needs can vary by age and health status.

How to Calculate Calcium/Phosphorus Ratio?

The following steps outline how to calculate the Calcium/Phosphorus Ratio.

  1. First, determine the amount of calcium (Ca) in milligrams (mg).
  2. Next, determine the amount of phosphorus (P) in milligrams (mg).
  3. Finally, calculate the ratio using the formula R = Ca / P.
  4. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Calcium (Ca) = 800 mg

Phosphorus (P) = 400 mg