Petrol prices in India are revised daily at 6 AM, and the rate at a pump in Pune can sit ₹2–3 higher or lower than one in Nagpur on the same morning. Most drivers never notice. The ones who track fuel costs properly always do.
The price displayed at an Indian petrol pump is not a national number. It never was. It is a city-specific number, set fresh every morning at 6 AM by oil marketing companies, and it moves based on the previous day's international crude price, the rupee-dollar exchange rate, central and state taxes, dealer margins, and transport costs to that specific city. Two pumps in two different cities can show rates that diverge by ₹2–4 per litre on the same day, even when they're selling identical E20 petrol from the same refinery.
That gap sounds small. Run the numbers across a full month of urban driving and it stops feeling small at all.
How Daily Price Revision Actually Works
The Dynamic Fuel Pricing system has been in place since June 2017. Before that, prices were revised roughly every fortnight. Now oil marketing companies recalculate the retail price overnight and push it to pumps at 6 AM. The revision mechanism tracks a 15-day rolling average of international crude prices and the rupee-dollar rate, then layers in the fixed costs that vary by location: excise duty (central, uniform across the country), value-added tax or VAT (state-level, varies significantly), freight charges to the depot, and the dealer commission.
VAT is where city-to-city variation comes from. Rajasthan charges among the highest VAT on petrol in the country. Goa sits at the lower end. Maharashtra falls somewhere in the middle, but Mumbai's cess adds another layer. A vehicle crossing a state border is not buying the same-priced fuel even if the base crude cost is identical on both sides of that border.
The 6 AM reset means the price you paid at 5:45 AM is technically valid, but the price after 6:01 AM on the same day at the same pump may already be different, higher or lower by a few paise or even a rupee, depending on how markets moved overnight. In practice, the change is rarely dramatic on a daily basis; the swings that matter accumulate over weeks and months.
The Mileage Calculation That Most Drivers Get Wrong
Here is the calculation most drivers run mentally: divide kilometres driven by litres consumed, get a mileage figure, and call it done. The problem is that this number is only useful for comparing one tank to another if the price stays constant. For cost-per-kilometre tracking, which is the number that actually tells you what you spend, price variation wrecks the comparison unless you log it every time you fill up.
Consider a realistic example. A mass-market hatchback with a 35-litre tank averages 15 km/l in city driving. A full fill costs roughly ₹3,570 at ₹102/litre. Drive 525 km on that tank and your cost per kilometre is ₹6.80. Now drive that same vehicle in a city where petrol sits at ₹106/litre, same fill, same 525 km. Cost per kilometre is ₹7.08. That ₹0.28/km difference does not sound like much until you apply it to an annual distance of 15,000 km: the gap is ₹4,200 per year, just from living in a city with higher VAT, driving the same route with identical habits.
If you commute across city limits, that gap can show up in a single month. Offices in Gurugram attract workers from Delhi; prices in the two cities have historically differed by ₹1–2 per litre. Someone filling up in Gurugram rather than Delhi over 12 months can spend noticeably more or less depending on which direction the gap runs, and it flips periodically.
Why "Kitna Deti Hai?" Is a City-Relative Question
The classic Indian mileage question, "kitna deti hai?", is almost always answered with a manufacturer's claimed figure or a rough personal estimate. Neither accounts for where you are. A vehicle returning 14 km/l in Bengaluru traffic costs more per kilometre to operate than the same vehicle returning 14 km/l in a city where petrol is ₹3 cheaper. Same mileage, different economics.
This is why comparing your mileage number against your neighbour's mileage number for the same model is mostly meaningless unless you are both in the same city, filling at the same point in the pricing cycle. Your tank-to-tank figures tell you what your vehicle does in your conditions. The cost-per-kilometre figure ties that performance to the actual money leaving your account. Both numbers matter; only one of them shows up on the fuel gauge.
For a longer treatment of the tank-to-tank measurement method itself, the post on how to measure kitna deti hai properly covers the fill-to-fill protocol in full. And if you have already been tracking mileage but not yet updated your baseline since the E20 rollout, the post on recalculating cost per kilometre on E20 walks through exactly what to revisit.
State Tax Tables Are Not Where You Find Today's Number
Plenty of websites publish state-wise VAT tables on petrol. Some are accurate, some are months out of date. VAT rates do change: states revise them for revenue reasons, for election cycles, for relief measures during crude price spikes. The table that was correct in January may be wrong in July. The only authoritative number for your city today is the actual pump price at a station near you, and that number changes at 6 AM.
This is not academic. If you are planning a long-distance drive through multiple states and want to know where to fill up strategically, you need city-level prices for that day, not a VAT table that may be six months stale. The difference between filling a 50-litre tank in one city versus another can be ₹150–200 on a single fill when prices diverge by ₹3/litre. Over a Ladakh trip or a Rajasthan circuit drive, with multiple fills in multiple states, that calculation is worth doing before you leave, not after.
Bharometer
Log every fill-up with today's city price, track true tank-to-tank mileage, and see your real cost per kilometre, updated automatically as daily rates change.
Why Logging the Price at Fill-Up Time Is the Only Accurate Method
If you track fuel costs with a spreadsheet or a note on your phone, you have probably typed in "litres filled" and "amount paid" and then derived mileage from the distance covered. The amount-paid method is accurate for what you spent, but it buries the price-per-litre signal inside a total. You cannot look back three months later and ask: was my cost-per-kilometre higher in February because the price was up, or because I was driving shorter, hotter urban trips with more AC use?
Logging the per-litre rate at each fill-up separates the two variables. Your mileage figure tells you about the vehicle and your driving conditions. The price figure tells you about the fuel market in your city. Cost per kilometre is the product of both. When you have all three data points for every fill, you can see which one moved when your monthly fuel spending changed.
Bharometer captures litres filled, amount paid, and the per-litre rate for every fill-up. The pump-scan feature photographs the pump screen and auto-fills those numbers without manual entry, which matters because the moment after you finish filling is the moment you are least likely to bother opening a tracking app. It also pulls city-level daily fuel prices, so you have a reference for the day's rate even before you scan. The cost-per-kilometre figure updates automatically as you log distances between fills.
CNG tracking works differently because the unit is kg rather than litres, and mileage reports as km/kg rather than km/l. If your vehicle runs on dual fuel, petrol and CNG, Bharometer handles both in the same vehicle record, which is useful for understanding which mode actually costs less per kilometre at current city prices, since that balance shifts as CNG prices revise (CNG prices also change, though on a less rigid daily schedule than petrol).
Reading the Monthly Pattern
Once you have three or four months of fill-up logs with city prices attached, a pattern becomes readable. Indian petrol prices tend to hold flat for weeks during periods of stable crude, then jump or drop in a cluster of daily revisions when crude moves sharply. If you log through one of those adjustment cycles, you will see your cost-per-kilometre line move even though your mileage stayed steady. That separation is only visible when you have the price variable isolated in your data.
It also becomes possible to answer a question that most drivers estimate rather than measure: what does filling up in a different city actually save or cost? If you drove from Pune to Goa for the long weekend and filled up twice in Goa, you either benefited from or paid a premium against Pune prices depending on that month's VAT differential. Your log records both fills with both prices. Over several such trips, you get a real number for how much city-of-fill-up affects your annual fuel spend.
The running-cost view in the app also surfaces monthly fuel spending as a total, which is useful for personal budgeting in a way that mileage figures are not. Knowing your vehicle returns 13 km/l does not tell you how much petrol you spent in July. Knowing you spent ₹4,800 on petrol in July does, and if Bharometer's log shows that ₹4,200 of that went to petrol and ₹600 to toll plazas (once you are noting toll costs separately), the picture is complete enough to actually act on.
The 6 AM Number Is the Starting Point, Not the End
Daily price revision is a feature of how Indian fuel markets now work, not a quirk to work around. The 6 AM reset means that every fill-up you make has a specific, trackable price attached to it, one that reflects real market conditions in your city on that day. That is actually more data than most drivers had access to ten years ago, when prices sat unchanged for two weeks at a time regardless of what crude did.
The only question is whether you use that data or ignore it. Ignoring it means your sense of fuel costs stays perpetually approximate: "it costs around ₹100 a litre these days, give or take." Using it means your cost-per-kilometre figure is precise, city-adjusted, and comparable across months even when prices move. The second version is the one that tells you whether your fuel spending is under control or not, and whether a mechanical issue, a driving habit, or a market price change is responsible when it moves.
That distinction, between approximate and precise, is the whole point of tracking fuel at the fill-up level rather than from memory.