Calculate your consumption and estimated bill based on meter readings and utility rates.
Calculation Summary
Total Usage (CCF):0.00
Energy Content (Therms):0.00
Gas Supply/Delivery Cost:$0.00
Service & Taxes:$0.00
Estimated Total Bill:$0.00
The Natural Gas Rate Calculation Formula
Understanding your natural gas bill requires knowing how raw volume (measured by your meter) is converted into energy units (Therms). Utility companies typically use the following multi-step formula to determine your monthly charges:
1. Volume Used (CCF) = Current Reading – Previous Reading
2. Energy (Therms) = Volume (CCF) × Thermal Factor
3. Gross Cost = (Therms × Rate per Therm) + Fixed Charges
4. Total Bill = Gross Cost + (Gross Cost × Tax Rate)
Key Definitions
CCF: Represents 100 Cubic Feet of gas volume. This is what your physical meter typically measures.
Thermal Factor: A multiplier that adjusts for the heat content (BTU) of the gas and atmospheric pressure. Since the energy density of gas can vary, this factor ensures you pay for the energy provided, not just the space it occupies.
Therm: A unit of heat energy equal to 100,000 British Thermal Units (BTUs). One CCF is roughly equal to one Therm, but the Thermal Factor provides the precise conversion.
Rate per Therm: This often includes both the "Supply" price (the cost of the gas itself) and the "Delivery" price (the cost of pipes and maintenance).
Practical Example
Suppose your previous meter reading was 5,000 CCF and your current reading is 5,100 CCF. You have used 100 CCF of gas. If your utility's Thermal Factor is 1.037, your energy usage is 103.7 Therms.
At a rate of $0.90 per Therm, your usage cost is $93.33. Adding a $15.00 monthly service fee brings the total to $108.33 before taxes.
function calculateGasRate() {
var prev = parseFloat(document.getElementById('prevReading').value);
var curr = parseFloat(document.getElementById('currReading').value);
var factor = parseFloat(document.getElementById('thermalFactor').value);
var rate = parseFloat(document.getElementById('ratePerTherm').value);
var service = parseFloat(document.getElementById('serviceCharge').value) || 0;
var taxPercent = parseFloat(document.getElementById('taxRate').value) || 0;
if (isNaN(prev) || isNaN(curr) || isNaN(factor) || isNaN(rate)) {
alert("Please enter all required fields with valid numbers.");
return;
}
if (curr < prev) {
alert("Current reading cannot be less than the previous reading.");
return;
}
var usageCCF = curr – prev;
var therms = usageCCF * factor;
var variableCost = therms * rate;
var subtotal = variableCost + service;
var taxAmount = subtotal * (taxPercent / 100);
var totalBill = subtotal + taxAmount;
document.getElementById('resUsageCCF').innerText = usageCCF.toFixed(2);
document.getElementById('resTherms').innerText = therms.toFixed(3);
document.getElementById('resVariableCost').innerText = "$" + variableCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resFixedTax').innerText = "$" + (service + taxAmount).toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resTotal').innerText = "$" + totalBill.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('gasResult').style.display = 'block';
}