A route can look fine on paper and still leave you with an out-of-gas call at 7:00 a.m. The usual reason is not that dispatch forgot a customer. It is that the schedule relied on the wrong measure of fuel use. In the question of degree days versus estimates, both methods have a place, but they do not give you the same level of control.
An estimate may be enough for a steady account with a known pattern. Degree days are usually the better tool when weather drives consumption and delivery timing matters. The practical answer for most fuel dealers is not choosing one and ignoring the other. It is knowing which accounts can safely run on an estimate, which ones need weather-based scheduling, and when a dispatcher needs to step in.
What degree days measure
Heating degree days measure the weather demand that causes a home or building to burn fuel for heat. When temperatures fall below a base temperature, commonly 65 degrees, the difference is counted as heating degree days. A colder day produces more degree days. A mild day produces fewer or none.
For a heating oil customer, accumulated degree days give you a useful way to track how much of the tank should have been used since the last delivery. If an account normally burns one gallon for every five degree days, 500 accumulated degree days suggest roughly 100 gallons have been used. Combine that figure with the tank size, fill percentage, and delivery history, and you have a much better basis for scheduling than a date on the calendar.
That is the value of degree day scheduling. It ties expected consumption to the weather the customer actually experienced, rather than assuming every January or February looks the same.
It is not magic. A degree-day calculation is only as good as the account setup, the local temperature data, and the customer information behind it. But once those pieces are reasonably accurate, it gives dispatch a repeatable way to prioritize the route before tanks get low.
What estimates measure
An estimate is a prediction based on a simpler assumption. It may use average daily burn, a fixed number of calendar days between deliveries, last year’s gallons, or the dispatcher’s experience with that account. Sometimes it is entered as a gallons-per-day figure. Sometimes it is simply, “Put them on every 30 days.”
There is nothing wrong with estimates when the pattern is stable. A commercial account with consistent equipment use may be easy to project. A customer who uses propane primarily for cooking may not need daily weather tracking at all. Calendar scheduling can also work well for customers who want a regular delivery pattern and have enough tank capacity to cover normal swings.
The problem starts when an estimate is treated as a guarantee. Fuel use changes with weather, occupancy, thermostat settings, construction changes, new appliances, and equipment problems. A homeowner may be away for two weeks, then return during a cold snap. A restaurant may add patio heaters. A building may have a failed furnace control that runs the system longer than it should. The estimate does not know any of that unless someone updates it.
Degree days versus estimates: the operational difference
The difference shows up in the morning when you are building a route. An estimate tells you what an account is expected to need based on a general pattern. Degree days show whether recent weather has pushed that account ahead of or behind the pattern.
Consider two oil customers normally scheduled every 28 days. Both received 150 gallons at their last delivery. One month is mild, and the next month has several days well below normal. A calendar estimate may put both accounts on the same route at the same interval. A degree-day schedule will recognize that the colder account conditions require an earlier delivery.
That matters because delivery work has real limits. Trucks have capacity. Drivers have hours. Storms affect roads. A schedule that identifies at-risk tanks early gives dispatch time to make good decisions. A schedule based only on broad estimates can force last-minute changes, expensive special trips, and avoidable out-of-gas service.
For many dealers, the best workflow is to use degree days for automatic customers whose consumption is heat-driven, use calendar days or estimates for steady low-use accounts, and keep call-in orders separate. That is not overcomplicating the operation. It is matching the scheduling method to the account.
When degree days are the better choice
Degree days generally earn their keep when weather is the main reason fuel use moves up or down. That includes residential heating oil accounts and many propane heating accounts. They are especially useful when you have a large number of automatic customers, several delivery areas, or enough winter volume that a few missed tanks can throw off the day.
They also help when a dispatcher is covering for someone else. An experienced dispatcher may know that a particular customer “usually runs short in February.” A system based on updated degree days puts that knowledge into a usable schedule instead of leaving it in one person’s head.
Local weather data matters here. Using temperatures that reflect the customer’s actual service area is more useful than relying on a distant airport or a broad regional average. Even within one state, elevation, coastal conditions, and storm patterns can change heating demand enough to affect a route.
When estimates are the better choice
Estimates are often more practical for accounts where heating demand is only part of the picture. Propane customers who use fuel for cooking, water heating, generators, pool heaters, or agricultural equipment may not follow a clean degree-day pattern. A degree-day model can still contribute to the calculation, but it should not be the only number driving the delivery date.
New accounts are another example. Until you have delivery history, you may need to start with an estimate based on tank size, stated appliances, household size, and a conservative delivery threshold. Once you have a few deliveries and a season of actual usage, the account can be adjusted.
Estimates are also useful as a sanity check. If degree-day results say an account should need fuel much sooner or later than usual, that is worth reviewing. The account may have the wrong K-factor, a changed appliance load, an inaccurate tank size, or a delivery that was entered incorrectly.
The numbers must be maintained
Neither method survives bad account data. A schedule can only work if the tank size, delivery quantity, estimated fill level, and consumption settings are kept current. A customer who replaces an old furnace, installs a new addition, changes from oil heat to a heat pump, or adds propane appliances needs an account review.
This is where many manual operations lose ground. A handwritten ticket gets filed, a gallon total is not entered until later, and the next schedule runs on old information. Small errors compound quickly during cold weather. One missed delivery entry can make a tank appear safer than it is.
A fuel delivery system should update delivery history promptly, load current temperature readings, and give dispatch a clear list of accounts that need attention. Degree Days Online is built around that day-to-day workflow, including degree day scheduling, calendar scheduling, delivery tickets, and call-in orders in one operating system.
Set a delivery threshold with room to work
The goal is not to schedule every tank at the last possible moment. A practical delivery threshold gives you enough fuel remaining to handle a route change, a storm day, a truck issue, or a sudden burst of cold weather.
The right threshold depends on the tank, the account’s burn rate, route density, and how often you can reasonably serve the area. A high-use customer on a 275-gallon tank needs more attention than a low-use customer with a large propane tank. A remote account may need a wider safety margin than one located near several daily stops.
Review exceptions instead of blindly accepting them. Accounts that repeatedly appear too early may have an overstated usage factor. Accounts that repeatedly show up late are more urgent. Adjust the settings, document the reason, and let the schedule improve over time.
The best schedule is not the one with the most complicated formula. It is the one your office can trust on a busy winter morning. Use degree days where weather truly drives demand, use estimates where they fit the account, and leave enough room in every route to keep a normal cold snap from becoming an emergency.