Free health tools
Check a number. Save it. The rest follow.
Emergency? Call your local emergency number. Do I need a doctor today?
Start here
Tests that track lifespan
Track your numbers
Test yourself
Plan your habits
Or pick the result you are holding
A result is rarely the only one on the page. Each of these gives the bands, in both unit systems, and what happens next.
- Cholesterol ratio6 bands
- CRP result5 bands
- Cycle length5 bands
- Do you need a booster for this wound?6 bands
- eGFR number11 bands
- Eosinophil count5 bands
- ESR result6 bands
- Every line on an EOB, in order6 bands
- Exercise heart rate7 bands
- Fasting triglyceride result4 bands
- Ferritin result6 bands
- HbA1c8 bands
- HDL result6 bands
- Health age result6 bands
The numbers these tools use
Written out, so you can check them, take them to your doctor, or work the answer yourself.
What blood pressure is too high?
Under 120 over 80 is normal. 120 to 129 with a diastolic under 80 is elevated. 130 to 139, or 80 to 89 diastolic, is stage 1. 140 over 90 or above is stage 2. Above 180 over 120 with symptoms is an emergency. One reading decides nothing: pressure moves with the hour, the cuff and the ten minutes before it, so the average of several readings across a week is what a doctor acts on.
Check a readingWhat HbA1c counts as prediabetes?
Below 5.7 percent is the normal range. 5.7 to 6.4 is the prediabetes range. 6.5 and above is the diabetes range on a repeated test. The prediabetes band is the one worth catching, because it is usually reversible and it carries no symptoms at all.
Convert A1c to average sugarWhat is a normal fasting blood sugar?
Fasting, 99 mg/dL and below is normal, 100 to 125 is the prediabetes range, and 126 and above on a repeated test is the diabetes range. Two hours after a meal, under 140 is normal and 200 or above is the diabetes range. Below 70 is low, and below 54 with symptoms needs treating on the spot.
Track your readingsWhat eGFR is normal?
90 and above is normal or high, and 60 to 89 is mildly decreased, which is usually ordinary with age. 45 to 59 and 30 to 44 are the moderate bands, 15 to 29 is severe, and under 15 is the kidney failure range. A single low result is not a diagnosis: the number has to persist for three months before it means chronic kidney disease.
Work it out from a creatinine resultWhich tool should I use if I only have one number?
Type it into the box at the top of this page. It reads blood pressure, HbA1c, cholesterol, eGFR, TSH, vitamin D, ferritin, CRP and two dozen other results, bands the value and says what usually happens next. If the number is not one it knows, it points you at the guide that explains it.
Try the result lookupWhat is a fever in an adult?
100.4 F, or 38 C, is the usual line for a fever. How high it goes matters far less than how long it lasts and what comes with it. A fever past three days, or one with confusion, a stiff neck, a rash that does not fade under pressure, or breathlessness, is a same-day call regardless of the reading.
Check a temperatureHow many calories do I actually need?
Start from your resting burn, which is set mostly by weight, height, age and sex, then multiply by how much you move: about 1.2 for a desk day, 1.55 for moderate activity, 1.725 for hard training. The number on a food label is a population average, not a prescription for you.
Get your numberWhat cholesterol ratio should I aim for?
Total divided by HDL under about 3.5 is good and above 5 is worth acting on. Non-HDL cholesterol, which is total minus HDL, tracks risk better than LDL alone for most people. No single figure decides anything on its own, and your blood pressure, smoking status and family history move the answer as much as the panel does.
Read your panelHow accurate are they?
A calculator is exactly as good as the number you put in and the assumption built into it. These are exact about the arithmetic and honest about the rest. Where a threshold is a range in the guidelines, the tool says so instead of inventing one figure.
What none of them can do is examine you. A result can sit inside a normal band and still matter in someone with kidney disease, a heart condition or a new symptom. Treat every answer as the start of a decision. When a tool says see a doctor, that is the answer, not a disclaimer.
Terms you will see
Your average blood sugar over roughly three months, as a percentage. One blood test, no fasting, and the most useful single number in diabetes.
Estimated glomerular filtration rate: how well the kidneys filter, worked out from a creatinine result plus age and sex. Reported in mL/min per 1.73 square metres.
The two blood pressure numbers. Systolic is the pressure as the heart pushes, diastolic the pressure as it refills. Written systolic over diastolic.
Two cholesterol carriers. LDL deposits into artery walls, HDL clears it away. This is why one is described as bad and the other as good, which is a simplification.
Weight over height squared. A population screening measure, not a verdict on one person, and it cannot tell muscle from fat. Waist adds what it misses.
The calories your body uses doing nothing at all. Every feeding or weight calculation starts here and is then multiplied by how much you move.
Tools measure. The Circle answers.
Members ask one question a month and the right expert answers from your saved numbers. $29 a month, cancel in two clicks.
Also in this section
Sorted against published guidelines. They do not diagnose, and they say so when a result needs a doctor.