Calculator glossary: plain-language terms for finance, health, math & more.

A Body Shape Index (ABSI) is an anthropometric metric that evaluates abdominal fat risk by normalizing waist circumference to height and BMI.

The alveolar-arterial (A-a) oxygen gradient is a clinical measurement of the difference between alveolar and arterial oxygen concentrations, assessing lung gas exchange efficiency.

A1C (Hemoglobin A1c) is a diagnostic blood biomarker measuring the percentage of glycated hemoglobin to estimate average blood glucose levels over the preceding 2 to 3 months.

The absolute eosinophil count (AEC) converts the eosinophil percentage from a WBC differential into an actual cell count, which is what determines eosinophilia severity.

A complete blood count with differential reports lymphocytes as a percentage of the total white blood cell count.

The absolute neutrophil count (ANC) converts a routine CBC differential into a single number that tells you how many infection-fighting neutrophils are actually circulating in the blood.

The absolute reticulocyte count (ARC) converts the reticulocyte percentage from a CBC into an actual cell count, giving a more reliable picture of how hard the bone marrow is working to replace red blood cells.

Acetaminophen (Tylenol) is one of the most commonly given pediatric medications, and also one of the most common causes of accidental drug overdose in children — almost always from stacking too many doses too close together, not from a single large dose.

This calculator compares the added sugar you eat or drink in a day against the American Heart Association's recommended daily limit — 25 g for women and 36 g for men — and converts the total to teaspoons so it's easier to picture.

Premature infants are often compared to developmental milestones designed for full-term babies, which can make a preemie appear "behind" when they are actually right on track for how early they arrived.

Adjusted body weight (AdjBW) is a calculated weight figure used, alongside actual weight and ideal body weight, to estimate medication dosing and nutrition needs for people whose actual weight is well above their ideal weight.

The exercise intensity below which energy production is almost entirely aerobic. Training below this threshold (typically 60–75% of max heart rate) improves base fitness with minimal recovery demand.

A D-dimer test is a common first step when venous thromboembolism (VTE) — deep vein thrombosis or pulmonary embolism — is suspected.

The albumin-to-creatinine ratio (ACR) is a spot urine test that screens for kidney damage by measuring how much albumin leaks into the urine relative to creatinine excretion.

The albumin/globulin (A/G) ratio compares the two main categories of blood protein — albumin and globulin — to help screen for liver disease, kidney disease, and conditions that raise antibody or other globulin levels.

Alcohol is often called an "empty calorie" source because it supplies energy without the nutrients found in most food, and its calories rarely appear on a nutrition label the way a soda's or a snack's do.

Knowing how many alcohol units are in your drink is the single most practical step toward making informed choices about your drinking.

The Aldrete Score is one of the most widely used tools for tracking a patient's recovery from anesthesia and deciding when they are ready to leave the post-anesthesia care unit (PACU).

Maximum allowable blood loss (MABL) estimates how much blood a patient can lose during surgery before their hematocrit falls to a clinician-chosen floor.

Acute appendicitis is one of the most common surgical emergencies, but its presentation overlaps with many other causes of abdominal pain.

The amniotic fluid index (AFI) is one of the two standard ultrasound methods for estimating how much amniotic fluid surrounds the fetus, alongside the single deepest pocket (SDP/DVP) technique.

Amoxicillin dosing for children is not one number — it depends on which infection is being treated, the child's age and weight, and whether the regimen comes from the FDA label or a professional-society guideline.

The exercise intensity at which lactic acid accumulates faster than it can be cleared, causing fatigue. Also called the lactate threshold. Training near this point improves performance and VO2 max.

The anion gap is a quick screening calculation from a basic metabolic panel — sodium minus the sum of chloride and bicarbonate — that flags whether unmeasured acids or other anions have accumulated in the blood.

The ankle-brachial index is a simple, non-invasive ratio that compares blood pressure at the ankle to blood pressure at the arm — and it's one of the most widely used screening tools for peripheral artery disease.

The APACHE II score turns a snapshot of a patient's first 24 hours in intensive care into a single number that reflects how critically ill they are.

The Apgar score is the standard first assessment of a newborn's condition, recorded by the attending clinician at 1 minute and 5 minutes after birth.

APRI — the AST to Platelet Ratio Index — is a simple, biopsy-free score built from two routine lab values that can flag liver fibrosis or cirrhosis.

Draw length is one of the two measurements — along with draw weight — that determine whether a bow fits you.

Army Directive 2026-13 now uses waist-to-height ratio (WHtR) as the sole Army body-composition assessment.

The Army Fitness Test (AFT) became the Army's physical fitness test of record on 1 June 2025, replacing the Army Combat Fitness Test (ACFT).

Arterial (or vascular) age reframes cardiovascular risk as an age instead of a percentage — a way of saying 'your combined risk factors look like those of a person this many years older than you, if that older person had ideal levels of everything else.' This calculator builds that estimate from a published, point-based cardiovascular risk model.

The AST/ALT ratio — also known as the De Ritis ratio — divides two liver enzymes to reveal a pattern, not just a level.

Blood Alcohol Concentration (BAC) measures the percentage of alcohol in the bloodstream, determined by drink volume, alcohol percentage, body weight, biological sex, and metabolic elimination rate.

Benzodiazepines vary enormously in potency by weight — a milligram of alprazolam is not comparable to a milligram of diazepam.

The bicarbonate deficit is a weight-based estimate of how much sodium bicarbonate would be needed to raise a patient's serum HCO3 from its current value to a target value.

Biological age measures how old your body functions compared to the population average for your years — giving you a more actionable health picture than the date on your birth certificate alone.

The biophysical profile (BPP) is an antepartum test that combines four ultrasound observations of fetal activity with the non-stress test to assess fetal wellbeing.

The Bishop score grades how ready the cervix is for induction of labor using five findings from a routine cervical exam.

Blood donation eligibility guidelines establish minimum donor age, body weight, hemoglobin levels, and safety deferral intervals required by the FDA and Red Cross for whole blood and apheresis donations.

The concentration of glucose (sugar) in the blood, measured in mg/dL. Normal fasting glucose is 70–99 mg/dL. Consistently elevated blood glucose is diagnostic of diabetes or prediabetes.

Blood pressure is one of the most important vital signs your doctor measures at every visit — and for good reason.

Blood glucose is reported in two different units depending on where you are: mg/dL in the United States, and mmol/L almost everywhere else.

Blood type follows clean Mendelian inheritance patterns established by Karl Landsteiner's 1900 discovery.

Estimated total blood volume is a reference figure used in transfusion medicine and fluid management, most often to calculate allowable blood loss or guide replacement volumes.

Body Mass Index (BMI) is a screening metric derived from a person's weight divided by the square of their height, used to categorize body weight and assess weight-related health risk.

Body mass index (BMI) is calculated the same way for children as for adults — weight divided by height squared — but a single BMI number cannot be read the same way for a child.

BMI is calculated the same way at any age — weight divided by height squared — but for a teenager that raw number means little on its own.

The number of calories your body burns at rest to maintain basic life functions like breathing, circulation, and cell production. BMR is the largest component of daily energy expenditure.

The BODE Index is a validated prognostic tool for chronic obstructive pulmonary disease (COPD), combining four independent domains — Body-mass index, airflow Obstruction, Dyspnea, and Exercise capacity — into a single 0-10 point score.

Body Adiposity Index is a body-fat estimate built from just two measurements — hip circumference and height — with no weight, age, or sex required.

Body fat percentage represents the proportion of total body weight composed of adipose tissue relative to lean mass such as muscle, bone, and organs.

Body frame size is a traditional, easy-to-measure way of estimating overall bone structure — small, medium, or large — using nothing more than your height and wrist circumference.

"Body recomposition" — losing fat and building muscle at the same time — sounds too good to be true, but it's genuinely supported by exercise science.

Body Roundness Index is a body-shape metric that uses your waist and height to estimate how much fat you carry — especially the central, abdominal fat most tied to health risk.

Body-shape typing — Pear, Apple, Hourglass, Rectangle — is a popular, easy way to describe how your waist, hip, and bust measurements relate to one another.

Body surface area is one of the most useful single numbers in clinical medicine.

The BUN/creatinine ratio is a simple bedside calculation — blood urea nitrogen divided by serum creatinine — that helps clinicians distinguish prerenal azotemia from intrinsic renal disease when kidney function tests are abnormal.

Burnout was formally recognized by the World Health Organization in ICD-11 (2019) as an occupational phenomenon — not a personal failing or weakness.

Caffeine is the most widely consumed psychoactive substance in the world, used daily by roughly 90% of Americans.

A unit of energy. In nutrition, the term usually refers to a kilocalorie (kcal) — the energy needed to raise 1 kilogram of water by 1 degree Celsius. Used to measure the energy content of food.

A calorie deficit is the single non-negotiable requirement for fat loss — but how large the deficit is, how it's structured, and how you protect muscle during it determines whether the weight you lose is actually fat.

The Calories Burned Calculator uses the MET framework to translate your body weight, activity choice, duration, and intensity into a concrete calorie and fat-burn estimate — helping you plan workouts, track deficits, and compare activities side by side.

Carbohydrate is the body's most flexible fuel — vital for endurance athletes, optional in very small amounts for keto dieters, and somewhere in between for everyone else.

The Calvert formula doses carboplatin to a target exposure (AUC) rather than by body surface area, which is why it needs an accurate glomerular filtration rate.

Cardiac index takes the single most important number in hemodynamics — how much blood the heart pumps per minute — and corrects it for the one variable that makes raw comparisons misleading: body size.

Cardiac output is the single number that captures how much blood the heart delivers to the body each minute — the product of how much it ejects per beat and how often it beats.

Most sore throats are viral and resolve without antibiotics, but distinguishing a viral sore throat from group A streptococcal pharyngitis by symptoms alone is unreliable.

Cerebral perfusion pressure (CPP) is the single number neurocritical care teams watch most closely after a severe brain injury — it captures, in one value, whether the brain is getting enough blood flow despite whatever is happening to intracranial pressure.

This calculator turns a series of timestamped cervical exams into a rate of change (cm/hr) and compares that rate to labor-progress benchmarks by parity.

Atrial fibrillation is the most common sustained cardiac arrhythmia, affecting more than 30 million people worldwide, and it carries a four-to-five-fold increase in the risk of ischemic stroke.

Child development milestone tracking monitors pediatric gross motor, fine motor, communication, and cognitive milestones across age intervals based on CDC and AAP developmental guidelines.

The Child-Pugh score (formally the Child-Turcotte-Pugh score) grades the severity of liver cirrhosis using five simple clinical and laboratory measures.

Cholesterol lipids (HDL and LDL) are essential fatty compounds in the bloodstream evaluated in lipid panels to screen cardiovascular disease and arterial plaque risk.

The cholesterol ratio, or TC/HDL ratio, is a simple screening figure that combines total cholesterol and HDL cholesterol from the same lipid panel into one number.

Lab reports show cholesterol and triglyceride results in one of two units depending on where you live: mg/dL in the United States, or mmol/L almost everywhere else.

Conception is possible during only about six days of every menstrual cycle — a narrow window that most people cannot pinpoint without understanding their own cycle.

The anion gap is a quick screening calculation, but it has a blind spot: it depends heavily on serum albumin, which is never directly included in the formula.

Total serum calcium readings are influenced by how much albumin is in the blood, because roughly 40% of calcium circulates bound to albumin.

After a platelet transfusion, the raw rise in platelet count depends heavily on the patient's size and how many platelets were transfused — so a bigger patient given a smaller dose can look like a 'poor responder' even with a completely normal transfusion response.

A raw reticulocyte percentage can be misleading in anemia, because it is a percentage of a shrunken red-cell pool rather than an absolute count.

When blood glucose is high, the measured serum sodium can look falsely low. This calculator applies the two published corrections — Katz (1.6) and Hillier (2.4) — to estimate the true sodium once glucose is accounted for, and shows both side by side so no single convention is silently assumed.