Calculators
Planning tools related to air quality & smoke-free living, with visible assumptions and clearly explained results.
Estimate air changes per hour from a room's volume and the airflow delivered by ventilation or filtration equipment. The result assumes the airflow rate is maintained and distributed through the room.
Estimate annual air filter spending by multiplying the number of filters replaced per year by the price of each filter. This simple estimate excludes labor, delivery, taxes, and other costs.
Estimate the electricity cost of running an air purifier over a chosen number of days using its power draw, daily operating hours, and your electricity price.
Calculate the combined face area of air purifier filters from their length, width, and quantity. The estimate assumes each filter is a flat rectangle and counts one face per filter.
Estimate the minutes needed for an air purifier to deliver one room-volume equivalent of clean air, using room volume and the purifier’s clean air delivery rate (CADR). This simplified turnover estimate assumes the room volume and CADR are accurate and does not account for mixing, filter condition, pollutant sources, or air leakage.
Estimate the airflow rate in cubic feet per minute (CFM) needed to exchange the air in a room within a chosen number of minutes. This room-volume model assumes ideal mixing and does not account for ventilation standards or equipment performance.
Estimate body mass index (BMI) from your weight and height using weight in kilograms and height in centimeters. The result is a screening measure and does not assess health on its own.
Estimate basal metabolic rate (BMR) in kilocalories per day using the Mifflin–St Jeor equation and your age, height, weight, and sex category used by the equation.
Add the caffeine amounts from drinks and foods you consume to estimate your total intake in milligrams. This simple tally does not assess personal safety or provide medical guidance.
Estimate daily maintenance energy needs for adults using the Mifflin–St Jeor equation and an activity multiplier. This is a general planning estimate, not a diagnosis or an individualized nutrition plan.
Estimate annual household emissions in kilograms of carbon dioxide equivalent (kg CO₂e) from electricity, car travel, and air travel using the illustrative factors shown in the formula. This simplified estimate excludes many other sources and is not a complete lifecycle assessment.
Estimate your daily steps by multiplying the number of walks you take by the steps in each walk. Enter your usual walk count and a reasonable step estimate for each walk.
Estimate total walking minutes per day by multiplying how many walks you take by the minutes in each walk. The estimate assumes each walk is the same length and does not account for pace, distance, or breaks.
Estimate a dehumidifier's nominal moisture-removal capacity in pints per day from room floor area, ceiling height, and a user-selected dampness level. This is a transparent planning estimate, not a manufacturer sizing standard.
Estimate dew point from air temperature and relative humidity using Mark Lawrence’s approximate moist-air rule of thumb.
Use your own inputs to calculate the result for duct airflow velocity.
Estimate the energy charge for an appliance or ventilation setup from its power, daily runtime, number of days, and electricity rate. The estimate excludes tiered rates, fees, and taxes.
Estimate electricity consumption in kilowatt-hours from an appliance's rated power, average daily operating time, and number of days. This is a usage estimate and does not calculate your bill.
Estimate the electricity cost of operating a device from its power draw, daily use, electricity rate, and number of days. This estimate assumes the device uses its stated power continuously while in use.
Estimate a fan's electricity cost from its wattage, daily operating time, days of use, and electricity price. The estimate assumes steady wattage and a constant price per kilowatt-hour.
Estimate a target heart rate from resting and maximum heart rate using the heart rate reserve method and a selected exercise intensity.
Estimate the water a humidifier uses from its operating time and water use rate, in liters.
Estimate a reference weight range from height using the adult body mass index (BMI) range of 18.5 to 24.9. This screening estimate does not account for individual body composition or health history.
Estimate the total number of replacement filters needed by multiplying the number of rooms by filters per room and planned replacement cycles. The estimate assumes the same filter count and replacement schedule for every room.
Estimate the remaining indoor smoke particle concentration over time using a simple exponential decay model. Enter an initial concentration, an hourly decay fraction, and elapsed hours.
Estimate lean body mass in kilograms from body weight and body fat percentage using a simple subtraction model. This estimate depends on the accuracy of the inputs and is not a clinical assessment.
Estimate the spending difference over a chosen period by comparing current cigarette costs with your expected post-smoking spending. This is a simple personal budgeting model based on the amounts you enter, not a promise of savings.
Estimate the annual rainwater volume a roof can collect using roof area, annual rainfall, and a collection efficiency assumption. This simplified estimate does not account for storage capacity or seasonal demand.
Calculate relative humidity as the ratio of actual water vapor pressure to saturation vapor pressure at the same temperature. Enter both pressures in the same units.
Calculate a room’s approximate air volume in cubic feet by multiplying its interior length, width, and height. This basic estimate assumes a rectangular room with consistent dimensions.
Estimate the total budget for replacement room filters using the number of filters, cost per filter in dollars, and number of replacement sets.
Estimate sleep efficiency as the percentage of time in bed that you estimate you spent asleep. Enter estimated asleep minutes and estimated time-in-bed minutes.
Estimate cigarette spending over a chosen period from daily use, pack size, and pack price. This estimate covers cigarette purchases only.
Estimate the sodium in foods and drinks you consume by adding the sodium amounts from their labels and serving counts. This is a tracking estimate, not a personalized health target.
Estimate solar energy production from panel capacity, average peak sun hours, system efficiency, and the number of days. The estimate uses steady average conditions and does not model weather or site-specific shading.
Estimate a broad exercise heart rate target range from age using the simple formula 220 minus age for estimated maximum heart rate, then apply a selected percentage range. Results are estimates for general fitness information, not individualized medical guidance.
Estimate annual electricity cost for a ventilation fan from its airflow rating, daily operating time, power draw, and electricity price. This is a simple fan-energy estimate and does not calculate whole-building ventilation costs.
Calculate air changes per hour (ACH) from a room's volume and the airflow supplied or exhausted per hour. This estimate assumes the entered airflow is representative of the room and does not measure air quality or confirm that ventilation is adequate.
Estimate VO₂ max from a timed 1-mile walk, your age, and your post-walk heart rate using the Rockport equation. This field estimate is not a laboratory measurement.
Calculate waist-to-height ratio by dividing waist circumference by height measured in the same units. This screening measure is for general wellness information and does not diagnose health conditions.
Calculate waist-to-hip ratio by dividing your waist circumference by your hip circumference. Enter both measurements in centimeters.
Estimate calories burned during a walk from body weight, walking time, and average pace using a simplified MET-based equation.
Estimate walking distance in kilometers from a step count and your average stride length in meters. This simple estimate assumes each counted step covers the same distance.
Estimate a household water bill from water used, the supplied rate per unit, and fixed service charges. This simple estimate excludes taxes and other charges unless you include them in the fixed charge.
Estimate a household's daily direct water use from indoor and outdoor activities, then scale it to an annual total. This worksheet uses the entered daily estimates and does not include indirect water used to produce food, clothing, or other goods.
Compare two scale readings to calculate their difference. The estimate treats the entire change as water weight, an assumption that may not match what caused the change.
Estimate the weekly cost of beverages by multiplying the number of drinks consumed per week by the price per drink. The result reflects the supplied inputs and does not include other costs.
Calculate total exercise time per week by multiplying the number of sessions by the minutes in each session.
Estimate total sleep hours in a week by multiplying the number of nights tracked by average sleep hours per night.
Estimate the minutes required for a chosen airflow rate to move air equal to one room volume through an open-window ventilation setup. This is a simple volume-to-flow calculation, not a measure of actual air replacement or indoor air quality.