Calculator
What the GFR Calculator does
GFR Calculator: calculates eGFR and CKD Stage (approx) from Serum Creatinine, Age and Sex. Example: serum creatinine 1 mg/dL, age 45 years and sex Female gives egfr 59.957.
Enter Serum Creatinine, Age, Sex and Race coefficient (older MDRD) and the GFR Calculator reports eGFR and CKD Stage (approx). The result recalculates on every keystroke without a button press or a page reload.
It is mostly used by people tracking a goal. Context matters more than the number itself. Age, build and activity all shift it.
There is no account, no upload and no server round trip, because the page does the work itself.
The meaning of each field, the formula in use, and a worked example that starts from the default inputs are all further down.
What do the GFR Calculator fields mean?
The GFR Calculator uses 4 inputs. The defaults are there to be replaced. They exist so the tool is never showing an empty result.
| Field | What to enter | Default |
|---|---|---|
| Serum Creatinine | measured in mg/dL; accepts 0.1 to 20 | 1.0 |
| Age | measured in years; accepts 18 to 100 | 45 |
| Sex | choose from Female or Male | Female |
| Race coefficient (older MDRD) | choose from Do not apply or Apply ×1.212 (legacy MDRD) | Do not apply |
How does the GFR Calculator work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same calculation.
Checks happen up front, so errors surface next to the form instead of hiding in the output.
Worked example
These are the values the GFR Calculator loads by default, and the result it produces from them. These are the tool’s own default values and the result they produce, not an invented illustration.
| Serum Creatinine | 1 mg/dL |
|---|---|
| Age | 45 years |
| Sex | Female |
| Race coefficient (older MDRD) | Do not apply |
| eGFR | 59.957 |
|---|---|
| CKD Stage (approx) | G3a |
| What this means | Estimated GFR ≈ 60 mL/min/1.73m² → G3a. Educational estimate only; labs use validated equations. |
How to use it
- Enter Serum Creatinine in mg/dL (0.1 to 20).
- Set Age in years (18 to 100).
- Pick a value for Sex: the options are Female or Male.
- Pick a value for Race coefficient (older MDRD): the options are Do not apply or Apply ×1.212 (legacy MDRD).
- Each keystroke triggers a fresh calculation, which is cheap because it happens locally.
- You get eGFR, CKD Stage (approx) and What this means back.
- Both Copy Link and Print capture the current state, so pick whichever suits how you file things.
What this tool does not do
- Body composition, ethnicity and age all shift what a "normal" result means.
- These formulas come from population averages and cannot account for your medical history.
- There is no audit trail: if you need one, record the inputs alongside the output.
- It validates ranges, not intent. A value can be accepted and still be the wrong one to use.
Frequently asked questions
Enter Serum Creatinine in mg/dL and Age in years. Look for the unit beside each label; the result is reported in a stated unit as well.
Serum Creatinine accepts 0.1 to 20 mg/dL. Out-of-range entries are refused up front, which is safer than silently clamping them.
With the values loaded when the page opens, egfr comes out as 59.957. It recalculates the moment an input changes, which makes comparing scenarios quick.
Not at all: the whole thing runs offline once the page has loaded, which tells you nothing is being sent.
It costs nothing, and there is no limit on repeat use.
Good enough to track a trend over time, not precise enough to act on a single reading. Repeat measurements under the same conditions tell you far more than one number does.