Relief Petrol guide
Build a fuel budget from your own kilometres
A useful budget is not a guess about what a vehicle “should” consume. It is a small measurement: distance driven, litres added, and the price actually paid. This guide turns that record into trip, weekly, and monthly estimates without using a current or invented fuel price.
The three formulas
litres needed = planned kilometres ÷ km/L
fuel cost = litres needed × price per litre
Keep the units consistent. If your odometer is in kilometres and the pump is in litres, the result is km/L. Do not divide kilometres by rupees, and do not compare a dashboard’s instantaneous reading with a full-tank measurement.
For a monthly estimate, add the kilometres for each regular journey first. Then add a reasonable allowance for errands or weekend driving, divide by measured km/L, and multiply by the scenario price. Round only at the end so small errors do not compound.
How to measure real-world km/L
- Fill to a consistent stopping point. Use the same pump and safe, repeatable method where possible. Record the odometer or trip-meter reading and litres added.
- Reset the trip meter. If you cannot reset it, photograph or write down the starting odometer number.
- Drive normally. Keep the conditions in your note: city traffic, motorway, passengers, air-conditioning, hills, and traffic delays.
- Refill at the same reference point. At the next fill, record the new distance and the litres needed to return to the same level.
- Calculate. Divide the distance since the last fill by litres added. Example: 420 km ÷ 35 L = 12 km/L.
- Repeat. Two or three fills are more useful than a single short trip. Average comparable records rather than mixing a traffic-heavy commute with an empty-car motorway run.
Worked example: price a hypothetical trip
The following is deliberately hypothetical; it is not a current Pakistan fuel price.
| Distance | 360 km |
|---|---|
| Efficiency | 12 km/L |
| Fuel needed | 360 ÷ 12 = 30 L |
| Estimated cost | 30 × Rs 280 = Rs 8,400 |
For a round trip, double the planned distance before dividing: 720 km ÷ 12 km/L = 60 L; 60 L × Rs 280 = Rs 16,800. Add a clearly labeled buffer only if your route is uncertain; do not hide it inside the efficiency figure.
Worked example: estimate a month
Suppose a driver travels 38 km per workday for 22 days, then adds 120 km for errands. The measured efficiency is 13.5 km/L. The scenario price is Rs 285/L.
Monthly distance: 836 + 120 = 956 km
Fuel: 956 ÷ 13.5 = 70.8148 L
Cost: 70.8148 × Rs 285 = Rs 20,182.22 (about Rs 20,182)
If you budget in whole rupees, round the final estimate to Rs 20,200 or set aside a small separate contingency. Do not round 13.5 km/L to 14 before doing the division: 956 ÷ 14 × 285 would produce about Rs 19,440, which understates this scenario by about Rs 742.
To update the estimate after checking a new official rate, change only the scenario price in the final multiplication. Your measured distance and km/L remain separate inputs.
Use the site’s fuel tools
For a quick fill-up or trip calculation, open Fuel tools. Enter a dated or clearly labeled price assumption, your distance, and your measured efficiency. If you are checking a live price, verify its effective date first; a calculator cannot detect a stale input.
The tool is for estimates. Your receipt, route, traffic, loading, and vehicle condition determine the actual result.
When efficiency comparisons mislead
“Vehicle A gets better mileage than Vehicle B” is incomplete unless the test conditions match. Compare the same fuel-price assumption, distance, route type, load, tyre condition, weather, and driving pattern. A dashboard estimate can also differ from a refill-based calculation.
Different units are another trap. A vehicle rated in L/100 km uses less fuel when the number is lower; a vehicle reported in km/L uses less fuel when the number is higher. Convert before comparing.
| Vehicle | Efficiency | Scenario price | Fuel cost |
|---|---|---|---|
| A | 14 km/L | Rs 285/L | 1,000 ÷ 14 × 285 = Rs 20,357.14 |
| B | 10 km/L | Rs 270/L | 1,000 ÷ 10 × 270 = Rs 27,000 |
Vehicle A costs less in this scenario even though its assumed fuel price is higher. That conclusion depends on the stated assumptions; change the route, load, or measured efficiency and the gap can change.
Make the budget useful month after month
- Keep a simple log with date, odometer, litres, amount paid, route type, and unusual load or traffic.
- Use a low and high efficiency range if your driving varies. For example, calculate once at 11 km/L and once at 14 km/L rather than presenting one false-precision number.
- Separate fuel from tolls, parking, maintenance, and financing. They are real travel costs, but they do not belong in the fuel-rate formula.
- Recheck the price input whenever an official notification changes the effective rate.
- Keep estimates private and local: no registration, CNIC, bank details, or payment is needed to do this maths.