Fitness and health
Body measurements, energy and pace, with the formula named.
17 calculators
- BMI CalculatorBMI is a rough screening number, not a diagnosis. It is useful for spotting a trend and useless for telling a muscular person anything at all.
- Calorie CalculatorThis uses the Mifflin-St Jeor equation, which is the one most dietitians reach for. It gives what you burn in a day, then what to eat to move in either direction.
- Body Fat CalculatorThis is the US Navy tape method. All you need is a tape measure, and it gets within about three or four percent of a proper body scan, which is enough to track a direction.
- Protein Intake CalculatorProtein needs scale with body weight and with what you are asking your body to do. This gives a daily target and, more usefully, a per-meal one.
- Water Intake CalculatorThe eight glasses rule was never based on anything. Intake scales with your size, how much you sweat and how hot it is, so this starts from those.
- Ideal Weight CalculatorFour formulas, four answers, all of them defensible. They were written for drug dosing rather than for aesthetics, and the spread between them is the honest part.
- Macro CalculatorEnter your daily calories, from the calorie calculator or from experience, and pick a split. The grams matter more than the percentages, so those come first.
- Sleep CalculatorSleep runs in cycles of about 90 minutes. Waking at the end of one feels far better than waking in the middle, even when the middle gives you more sleep.
- Heart Rate Zone CalculatorEnter your age, and your resting heart rate if you know it. With a resting rate this uses the Karvonen method, which is noticeably more accurate than percentages of maximum.
- Waist to Hip Ratio CalculatorWhere fat sits matters more than how much of it there is. These two ratios predict health risk better than BMI does, and they need nothing but a tape measure.
- BMR CalculatorWhat your body burns at complete rest. Three accepted equations are shown side by side, because they disagree by a few hundred calories and it is worth seeing that.
- TDEE CalculatorWhat you actually burn in a day, resting plus moving. Every activity level is listed, because overestimating that multiplier is the single most common reason a diet stalls.
- Running Calorie CalculatorCalories burned on a run, from your weight, your distance and your pace. It uses published MET values rather than the flat 100 per mile rule, which is only right in the middle.
- Pregnancy Due Date CalculatorEnter the first day of your last period and you get the due date, how many weeks along you are today, and the dates the trimesters and the main milestones fall on.
- Ovulation CalculatorEnter the first day of your last period and your usual cycle length. You get the likely ovulation day and the fertile window around it, dated day by day.
- Dog Age CalculatorThe seven-times rule is wrong at both ends. This uses the staged rule vets use, adjusted for size, and shows the epigenetic formula alongside it.
- Blood Alcohol CalculatorAn estimate of blood alcohol content from what you drank, your weight and the time since the first drink. It is an estimate only, it can be badly wrong for any one person, and it is never a reason to drive.
Reading the results
Each calculator names the formula it uses, such as Mifflin-St Jeor for BMR or the US Navy method for body fat, so you can see where a number comes from and compare it with what a doctor or trainer gives you.
BMR is the energy your body uses at rest. TDEE adds your daily activity on top. The calorie and macro calculators start from TDEE and adjust it for your goal, which is why they ask how active you are. BMI, ideal weight and waist to hip ratio are screening measures: useful for tracking change over time, but none of them can tell muscle from fat on its own.
These results are estimates for planning, not medical advice. For pregnancy, ovulation, blood alcohol or any health condition, check with a doctor before acting on a number.