Estimate your heating oil delivery total from gallons, price per gallon, and optional tank gauge readings.
Table of contents
How to use our Heating Oil Cost Calculator
- Choose How do you want to enter gallons?: Known gallons if you already know the order size, or Use tank gauge if you want the calculator to estimate gallons from your tank.
- Enter Gallons to buy, or in tank gauge mode enter Tank size, Current tank gauge, and Target fill level.
- Enter Heating oil price as the quoted $ per gallon before any separate Delivery fee or Sales tax on oil subtotal.
- Open Advanced options only if you need to add Delivery fee or Sales tax on oil subtotal, then click Calculate.
- Check Gallons used for cost estimate before using Estimated delivered heating oil total; if the gallons look too high or low, recheck the gauge percent and tank size.
Definitions
Heating oil: A petroleum fuel used in some home heating systems, especially in the Northeast United States [1].
Gallons to buy: The number of gallons you plan to order when you already know the order size.
Tank size: The tank's total rated capacity in gallons, not the gallons currently inside the tank.
Current tank gauge: The percent full shown on your tank gauge before the delivery.
Target fill level: The percent full you want the tank to reach after the delivery estimate.
Oil subtotal: The gallons used for the estimate multiplied by the heating oil price per gallon, before any separate fee or tax.
Delivered price per gallon after fee and tax: The estimated total divided by the gallons used, so separate fees and tax are spread across each gallon.
Common mistakes and quick fixes
Mistake: Entering a full tank size in Gallons to buy when you only need a partial delivery.
Fix: Use the actual order amount in Gallons to buy, or switch How do you want to enter gallons? to Use tank gauge.
Mistake: Typing 4 instead of 4.00 is fine, but typing a total bill amount in Heating oil price gives a huge result.
Fix: Enter the quoted price per gallon in Heating oil price, such as 4.20.
Mistake: Setting Target fill level equal to or below Current tank gauge in tank gauge mode.
Fix: Raise Target fill level above Current tank gauge, or choose Known gallons if you already know the delivery amount.
Mistake: Using 100 for Target fill level because you want a full tank, even if your supplier normally stops lower.
Fix: Enter the fill level you want to estimate in Target fill level, such as 80 if that is the planned stop point.
Mistake: Adding Delivery fee into Heating oil price and also entering it again in Delivery fee.
Fix: If the fee is already built into Heating oil price, leave Delivery fee at 0.
Mistake: Treating Delivered price per gallon after fee and tax as the supplier's posted price.
Fix: Use Heating oil price for the posted oil price; use Delivered price per gallon after fee and tax only to compare quotes with fees or tax included.
Limitations & Key Assumptions / Boundary Conditions
- The tank gauge helper treats the tank as if the percent reading maps evenly to gallons. Real tank shapes, gauge precision, and tank tilt can make the actual gallons differ.
- Sales tax on oil subtotal applies only to the oil subtotal in this calculator. Local tax rules and invoice wording can differ.
- Delivery fee is added after the tax calculation. If your supplier taxes delivery or includes delivery in the posted price, enter the numbers to match the quote.
- The estimate does not include discounts, minimum delivery charges, service contracts, budget plans, surcharges, or payment fees unless you include them in the entered price or fee.
- Heating oil price can change before delivery. Use the confirmed quote if you need a payment-ready estimate.
- The calculator estimates cost only. It does not estimate burn rate, days of heat remaining, or whether the delivery amount is allowed by a supplier's minimum order rule.
Methodology
How the gallons are chosen
If you choose Known gallons, the calculator uses the Gallons to buy entry directly.
order_gallons = gallons_ordered
If you choose Use tank gauge, it estimates the delivery gallons from Tank size, Current tank gauge, and Target fill level.
order_gallons = tank_capacity_gallons * (target_gauge_percent - current_gauge_percent) / 100
How the cost is calculated
The oil subtotal is the estimated gallons times Heating oil price.
oil_subtotal_cost = order_gallons * price_per_gallon
Sales tax is applied only to the oil subtotal because the field is labeled Sales tax on oil subtotal.
sales_tax_cost = oil_subtotal_cost * sales_tax_percent / 100
The estimated delivered total adds the oil subtotal, Delivery fee, and estimated sales tax.
total_delivered_cost = oil_subtotal_cost + delivery_fee + sales_tax_cost
The delivered price per gallon after fee and tax spreads the full delivered total across the gallons used for the estimate.
effective_delivered_price = total_delivered_cost / order_gallons
Mini-example
For a 275 gallon tank that is 25 percent full and a target of 80 percent, the gallons estimate is 275 * (80 - 25) / 100 = 151.25 gallons. At $4.00 per gallon with no delivery fee and no tax, the oil subtotal is $605.00, the estimated delivered heating oil total is $605.00, and the delivered price per gallon after fee and tax is $4.00 per gallon.
Input checks
The calculator blocks zero or negative gallons, negative prices or fees, invalid percent values, and a target fill level that is not higher than the current tank gauge. It also avoids dividing by zero when calculating the delivered price per gallon after fee and tax.