🧮Calculators
Calculators cover finance, health, math, physics, engineering and everyday life: interest and loans, net salary, BMI, rule of three, conversions and more. Results are informational and educational — for important decisions, confirm with a professional and official sources.
2904 tools
Froude Number
Compute the Froude number Fr = v/√(g·L).
Weber Number
Compute the Weber number We = (ρ·v²·L)/σ.
Wind Chill Index
Compute wind chill via the NWS formula.
Height from Arm Span
Estimate stature from arm span via the practical ratio rule.
Fat-Free Mass Index
Compute FFMI = lean mass (kg) / height² (m²).
Tanaka Max Heart Rate
Estimate max HR with Tanaka's formula: HRmax = 208 − 0.7 × age.
Gulati Max Heart Rate
Estimate female max HR via Gulati: HRmax = 206 − 0.88 × age.
Equivalent Radiation Dose
Compute equivalent dose H = D × WR (Sv).
Caffeine Decay
Estimate remaining caffeine after t hours assuming 5h half-life.
Blood Alcohol Decay
Estimate BAC after t hours using the linear Widmark elimination rate.
Aircraft Takeoff Speed
Estimate rotation speed VR ≈ 1.1·Vstall as a practical rule of thumb.
Stall Speed
Compute Vstall = √(2·m·g/(ρ·S·CLmax)).
Takeoff Distance Estimate
Estimate takeoff distance d ≈ V²/(2·a).
Jet Engine Thrust
Compute thrust F = ṁ·(Ve − V0).
Landing Distance Estimate
Estimate landing distance d ≈ V²/(2·a).
Aircraft Fuel Efficiency
Compute aircraft fuel efficiency = distance / fuel.
Density Altitude
Estimate density altitude DA = PA + 120·(OAT − ISA) in feet.
Parachute Terminal Velocity
Compute terminal velocity Vt = √(2·m·g/(ρ·Cd·A)).
Circular Orbit Period
Compute T = 2π·√(r³/(G·M)) for a circular orbit.
Journal Impact Factor
Compute JIF = citations / articles published in the two prior years.
Citations Per Paper
Compute average citations per paper = total citations / total papers.
Battery Life (mAh)
Estimate battery life: t (h) = capacity (mAh) / draw (mA).
Battery Charge Time (mAh)
Estimate charge time t (h) = capacity (mAh) / charger current (mA).
BMR Calculator (Mifflin-St Jeor)
Estimate basal metabolic rate with Mifflin-St Jeor: 10 x kg + 6.25 x cm - 5 x age, plus 5 for men or minus 161 for women. Result in kcal/day.
BMR Katch-McArdle
Calculate your basal metabolic rate with the Katch-McArdle formula, which uses lean body mass for a sharper estimate when you know your body-fat percentage.
Daily Protein Intake Calculator (g/kg)
Multiplies body weight by a g/kg target to show daily protein in grams, with five presets from 0.8 sedentary up to 2.2 hypertrophy.
Body Fat Calculator (US Navy)
Calculate your body fat percentage with the US Navy method, using neck, waist and hip measurements. No special scale required.
Cooper Test VO2max Calculator (12-Minute Run)
Estimates VO2max in mL/kg/min from the 12-minute Cooper run, using the field formula (distance in meters minus 504.9) divided by 44.73.
Karvonen Target Heart Rate Calculator (HRR)
Target heart rate by the Karvonen formula: HR_rest + intensity% of the heart rate reserve, with HR_max estimated as 220 minus your age, in bpm.
1RM Calculator (Brzycki)
Calculate your one-rep max (1RM) with the Brzycki formula from the weight lifted and the number of reps. Set your training loads with precision.
1RM O'Conner
Estimate your one-rep max (1RM) with the O'Conner formula from the weight lifted and reps performed. Plan training loads without attempting a true max.
Calories Burned by MET
Calculate how many calories you burn in a physical activity from its MET value, your body weight and the time spent. Compare running, lifting, cycling and more.
Child BMI (approximate Z-score)
Compute a child's BMI from weight and height and read it against the approximate CDC percentile bands for ages 5 to 17, where the same number means different things at different ages. Returns the BMI and the band it falls in. Enter weight, height and age.
Adult Height Predictor
Estimate how tall a child will be as an adult with the mid-parental method, using the height of both parents. A simple prediction based on genetics.
Heart Rate Recovery Calculator (1-Minute HRR)
Subtracts the heart rate measured 1 minute after exercise from peak heart rate and rates the drop: above 25 bpm excellent, 16 to 25 good, 15 or less fair.
VO₂max Rockport Walk Test
Estimate your VO₂max with the Rockport walking test (1 mile). Enter age, weight, time and heart rate to gauge your aerobic fitness.
Biological Age Calculator (Simple Estimate)
Adjusts your chronological age using sleep hours, weekly exercise and cigarettes per day for a rough biological age. Educational, not a clinical test.
Peak Respiratory Rate Estimator
Estimate your maximum respiratory rate from your age using a common rule of thumb. Useful as a reference for training, physiology and monitoring.
Heart Rate Training Zones Calculator (5 Zones)
Splits your max heart rate into the five classic training zones in bpm, from Z1 recovery at 50-60% up to Z5 VO2max at 90-100%.
Daily Energy Balance Calculator (Calorie Surplus)
Calculates your daily calorie surplus or deficit in kcal: intake minus total expenditure, where expenditure is BMR times an activity factor of 1.2 to 1.9.
Calorie Deficit Calculator for Weekly Weight Loss
Turns a target weekly fat loss into the daily calorie deficit you need, using 1 kg of body fat as about 7700 kcal: deficit = kg per week x 7700 / 7.
Rental Income Tax (Carnê-Leão)
Calculate the tax due on rental income under the Brazilian Carnê-Leão, using the monthly progressive income tax table. Know how much to pay each month.
DARF Day Trade Tax Calculator (Brazil, 20%)
Works out the 20 percent day trade income tax Brazilian traders pay through a DARF (federal tax payment form), applied to profit after brokerage fees.
Swing Trade Tax (DARF)
Calculate the tax due on swing trades via the Brazilian DARF: 15% on the monthly profit, with an exemption for sales up to R$20k. Know how much income tax to pay.
Crypto DARF Calculator (Brazil)
Works out the crypto DARF (Brazilian federal tax payment form): monthly sales up to R$ 35,000 are exempt; above that, 15% on the capital gain.
Carne-Leao Calculator (Brazil monthly income tax)
Enter the monthly taxable base and get the tax due under Brazil's 2024 progressive table: exempt to R$ 2,259.20, then 7.5% to 27.5%.
Self-Employed INSS Calculator (Brazil)
Monthly INSS (Brazil social security) contribution for self-employed workers: 11 or 20 percent of a base kept between the minimum wage and the INSS ceiling.
INSS Facultativo Calculator (Brazil social security)
Calculates the optional INSS (Brazil's social security) contribution in BRL at the 5% low-income, 11% simplified or 20% regular rate over your chosen base.
Net Pro-Labore Calculator
Calculate a partner net pro-labore after deducting the 11% INSS and withholding income tax. Know how much a business owner actually takes home each month.
Dividend Yield (DY)
Calculate a stock's dividend yield (DY) by dividing the dividends paid over a year by its current price. See how much a share pays out, in seconds.
P/E Ratio (Price/Earnings)
Calculate a stock's P/E ratio by dividing its share price by earnings per share. Compare companies and gauge whether a stock looks cheap or expensive.
ROE Calculator
Calculate ROE (return on equity) by dividing net income by shareholders equity. Measures the profitability generated for shareholders.
Gross Margin
Calculate gross margin as a percentage from revenue and cost of goods sold (COGS). See how much each sale keeps before operating expenses.
Markup vs Margin
Convert markup to profit margin and back, so you stop mixing the two up. Enter a percentage and instantly see the matching selling price.
Fund Management Fee Impact Calculator
Compounds an initial contribution at the gross annual return minus the management fee over the years you set and shows the final net balance in R$.
IPI Tax Calculator
Calculate the Brazilian IPI tax on a product from the tax base and rate. Instantly see the tax amount and the total price with IPI included.
Interstate ICMS Calculator
Calculate interstate ICMS tax on a sale using the 7% and 12% rates based on the origin and destination regions. Essential for issuing correct invoices in Brazil.
ITBI Calculator (Brazilian Property Transfer Tax)
Enter the property value and your city rate to get the ITBI, the Brazilian municipal property transfer tax. Typical rates run from 2% to 3%.
ITCMD: Brazil Inheritance and Gift Tax
Asset value times the state rate gives the tax due on a Brazilian inheritance or donation: 4 percent in Sao Paulo, 4 to 8 percent in Rio.
Recipe Scaler and Ingredient Multiplier
Scales a recipe by any factor: paste the ingredient list and each line has its leading quantity multiplied, so 200 g flour with factor 2 becomes 400 g.