BTU Calculator
Use this calculator to estimate the cooling needs of a typical room or house, such as finding out the power of a window air conditioner needed for an apartment room or the central air conditioner for a house.
AC BTU Calculator
square meters
square feet
meters
feet
Bedroom
Living Room
Kitchen
Average
Well Insulated
Poorly Insulated
Average
High
Low
Average
Hot
Cold
General Purpose AC or Heating BTU Calculator
This is a general purpose calculator that helps estimate the BTUs required to heat or cool an area. The desired temperature change is the necessary increase/decrease from outdoor temperature to reach the desired indoor temperature. As an example, an unheated Boston home during winter could reach temperatures as low as -5°F. To reach a temperature of 75°F, it requires a desired temperature increase of 80°F. This calculator can only gauge rough estimates.
meters
feet
meters
feet
meters
feet
Normal
Well Insulated
Poorly Insulated
Celsius
Fahrenheit
(e.g., 75°F for Boston winter, 45°F for Atlanta winter)
Error
Please enter valid positive numbers’; return; } // Convert to consistent units (square meters, meters) let area = sizeUnit === ‘square_feet’ ? size * 0.092903 : size; let height = ceilingHeightUnit === ‘feet’ ? ceilingHeight * 0.3048 : ceilingHeight; // Base BTU calculation (approx. 20-30 BTU per square foot, adjusted for factors) let baseBTU = area * 30; // Starting with 30 BTU/sq.ft as a baseline // Adjustments baseBTU += people * 400; // Additional BTU per person if (type === ‘living_room’) baseBTU *= 1.2; // 20% more for living room if (type === ‘kitchen’) baseBTU *= 1.3; // 30% more for kitchen if (insulation === ‘poor’) baseBTU *= 1.2; // 20% more for poor insulation if (insulation === ‘well’) baseBTU *= 0.9; // 10% less for well insulated if (sunExposure === ‘high’) baseBTU *= 1.1; // 10% more for high sun exposure if (climate === ‘hot’) baseBTU *= 1.2; // 20% more for hot climate // Adjust for ceiling height (basic adjustment) if (height > 2.5) baseBTU *= 1.1; // 10% more for heights > 2.5m document.getElementById(‘result’).innerHTML = `AC BTU Calculation
| Parameter | Value |
|---|---|
| Size | ${size} ${sizeUnit === ‘square_feet’ ? ‘sq ft’ : ‘sq m’} |
| Ceiling Height | ${ceilingHeight} ${ceilingHeightUnit} |
| Number of People | ${people} |
| Type | ${type.charAt(0).toUpperCase() + type.slice(1).replace(‘_’, ‘ ‘)} |
| Insulation Condition | ${insulation.charAt(0).toUpperCase() + insulation.slice(1)} |
| Sun Exposure | ${sunExposure.charAt(0).toUpperCase() + sunExposure.slice(1)} |
| Climate | ${climate.charAt(0).toUpperCase() + climate.slice(1)} |
| Estimated BTU | ${Math.round(baseBTU)} |
Note: Rough estimate; actual needs may vary based on specific conditions.
`; } function calculateGPBTU() { const width = parseFloat(document.getElementById(‘gpWidth’).value); const widthUnit = document.getElementById(‘gpWidthUnit’).value; const length = parseFloat(document.getElementById(‘gpLength’).value); const lengthUnit = document.getElementById(‘gpLengthUnit’).value; const ceilingHeight = parseFloat(document.getElementById(‘gpCeilingHeight’).value); const ceilingHeightUnit = document.getElementById(‘gpCeilingHeightUnit’).value; const insulation = document.getElementById(‘gpInsulation’).value; const tempChange = parseFloat(document.getElementById(‘gpTempChange’).value); const tempUnit = document.getElementById(‘gpTempUnit’).value; if (isNaN(width) || isNaN(length) || isNaN(ceilingHeight) || isNaN(tempChange) || width <= 0 || length <= 0 || ceilingHeight <= 0 || tempChange <= 0) { document.getElementById('result').innerHTML = 'Error
Please enter valid positive numbers’; return; } // Convert to consistent units (meters) let widthM = widthUnit === ‘feet’ ? width * 0.3048 : width; let lengthM = lengthUnit === ‘feet’ ? length * 0.3048 : length; let heightM = ceilingHeightUnit === ‘feet’ ? ceilingHeight * 0.3048 : ceilingHeight; // Convert temperature change to Celsius if in Fahrenheit let tempChangeC = tempUnit === ‘fahrenheit’ ? (tempChange * 5 / 9) : tempChange; // Volume in cubic meters const volume = widthM * lengthM * heightM; // Base BTU calculation (approx. 30-50 BTU per cubic meter per °C, adjusted) let baseBTU = volume * 40 * tempChangeC; // Baseline 40 BTU/m³/°C // Adjustments if (insulation === ‘poor’) baseBTU *= 1.2; // 20% more for poor insulation if (insulation === ‘well’) baseBTU *= 0.9; // 10% less for well insulated if (heightM > 2.5) baseBTU *= 1.1; // 10% more for heights > 2.5m document.getElementById(‘result’).innerHTML = `General Purpose BTU Calculation
| Parameter | Value |
|---|---|
| Room/House Width | ${width} ${widthUnit} |
| Room/House Length | ${length} ${lengthUnit} |
| Ceiling Height | ${ceilingHeight} ${ceilingHeightUnit} |
| Insulation Condition | ${insulation.charAt(0).toUpperCase() + insulation.slice(1)} |
| Desired Temp Change | ${tempChange} ${tempUnit === ‘celsius’ ? ‘°C’ : ‘°F’} |
| Volume | ${volume.toFixed(2)} m³ |
| Estimated BTU | ${Math.round(baseBTU)} |
Note: Rough estimate; actual needs may vary based on specific conditions and outdoor temperature.
`; }