Check Whether Cheaper Fuel Pays for the Detour — Free
The station with the lower board price is not always the cheaper fill-up once the detour burns fuel of its own. One receipt line: purchase saving on the litres you buy, minus the fuel the extra kilometres consume.
The proof surface
Rental prepay tools compare fuel offers attached to one hire. This receipt compares two pumps for a private fill-up: price difference × supplied litres against detour distance ÷ supplied economy, priced at the destination station. It does not price your time, tolls or wear.
InputOption code | price A per litre | price B per litre | extra round-trip km | economy km per litre; litres to buy at the pump (same in both places)
Rare deviceRental prepay tools compare fuel offers attached to one hire. This receipt compares two pumps for a private fill-up: price difference × supplied litres against detour distance ÷ supplied economy, priced at the destination station. It does not price your time, tolls or wear.
Output artifactBest net advantage with row-by-row context
Cost$0 local calculation · no card, paid key, subscription or signup · proposed filing price is not for sale
Sample, not your facts: Illustrative inputs: Tuesday run | 1.72 | 1.61 | 12 | 16; Weekend | 1.70 | 1.69 | 30 | 12. Litres to buy at the pump (same in both places) = 40. Best net advantage: 3.1925 net currency units. All records are invented.
Before using the fuel-detour receipt
Both prices must be quoted per litre at the pump for the same fuel grade; if one is per gallon or for a different grade, convert or correct it before entry. The litres figure is what you intend to buy — a full tank, a top-up — and applies to both options. Economy is your vehicle's real consumption in km per litre under detour-like driving; the tool deliberately takes it as supplied rather than guessing from a model name. Extra kilometres are the round-trip addition over your normal route, as you estimate them. The net figure ignores time value, tolls, tyre wear and the chance the queue at the cheap station eats the margin — all of which are yours to weigh around the arithmetic.
Why the flat version breaks
Comparing board prices without the drive
A 5-cent saving on 40 litres is 2.00; a ten-kilometre detour in a thirsty car can cost more than that in fuel alone. The board never shows the drive cost, so any detour decision made on board prices is incomplete by construction.
Using brochure economy for a stop-start detour
Official consumption figures flatter exactly the driving a detour usually is. Use your observed km/L from your own records; if you only have L/100 km, convert to km per litre first and note the convention. An optimistic economy figure silently flatters the detour.
Scaling one top-up to a lifestyle
The receipt prices one purchase under one assumption set. It does not prove that the cheaper station is always worth it across seasons, tank sizes and routes. Re-run with your next real fill-up numbers before making the detour a habit.
How to work the fuel-detour receipt
Quote both pumps in the same units
Take the per-litre price for the grade you actually use at each station, on the same day if possible. Where a board shows a member or app price, decide once which price you can really claim and use that convention on both rows. Currency and unit mismatches are the classic way this comparison goes wrong before any arithmetic.
Fix the litres you would buy
Use the amount you genuinely plan to purchase — usually your remaining tank capacity if filling, or your usual top-up. The saving scales with litres, so a small top-up rarely justifies a long detour; running the tool at your real quantity is the whole point.
Estimate the detour and economy separately
Extra round-trip km means the distance added versus the route you would otherwise drive; a station that is merely nearby but not on your path can still add kilometres. Economy should reflect the stop-start or extra-urban character of the detour, taken from your own records. Multiply them together only inside the formula: (km ÷ km/L) × destination price.
Decide with the net, not the board
A positive net is the purchase saving that survives the drive; a negative one means the road ate the deal. If the surviving margin is small, let time, queues and convenience decide without guilt. Nothing here obliges a trip — it prices one assumption set, and a different litres or km figure is a different answer.
What the fuel-detour receipt separates
Question
Before
Inspect this instead
Comparing board prices without the drive
A 5-cent saving on 40 litres is 2.00; a ten-kilometre detour in a thirsty car can cost more than that in fuel alone. The board never shows the drive cost, so any detour decision made on board prices is incomplete by construction.
Fix the litres you would buy
Using brochure economy for a stop-start detour
Official consumption figures flatter exactly the driving a detour usually is. Use your observed km/L from your own records; if you only have L/100 km, convert to km per litre first and note the convention. An optimistic economy figure silently flatters the detour.
Estimate the detour and economy separately
Scaling one top-up to a lifestyle
The receipt prices one purchase under one assumption set. It does not prove that the cheaper station is always worth it across seasons, tank sizes and routes. Re-run with your next real fill-up numbers before making the detour a habit.
Decide with the net, not the board
This fuel-detour receipt replaces a manual count or calculation, not source verification or the responsible person’s review.
Run it on the samples, right here
FIRST-LOAD
HYPOTHESIS / PROTOTYPE — checkout unavailable. Calculation is local. A draft is saved automatically in this browser profile when storage is available; Reset to sample clears it. Optional Pro history stores only five summaries and has its own deletion control. State links encode your inputs and can remain in browser history, clipboard or recipients’ records; share only non-sensitive rows. Optional external AI formatting leaves this device. The required site analytics beacon reports page activity; shared URLs contain encoded inputs. Do not treat an encoded URL as private. The calculator has no input-collection endpoint.
Travel-budget arithmetic on reader-supplied prices, distances and economy only, not a quote or a verified fuel offer. Confirm pump prices and plan driving within legal and safe limits; do not use this tool while driving.
Data note: The fuel-detour receipt processes Option code | price A per litre | price B per litre | extra round-trip km | economy km per litre locally. Starter/sample selection and Run compute in this tab; no input is sent by the calculator. A local draft may be saved; explicit state-link sharing or optional external AI formatting can disclose inputs. Use non-sensitive labels.
Go deeper: the companion app files the same reading as a till receipt with a tear-off foot
The article demo above runs without limits. The companion app keeps a local history, exports the rows as CSV, prints the fuel-detour receipt reading, and holds your drafts on this device — one complete free app run; the proposed $4 one-time filing layer is not for sale.
The fuel-detour receipt answer stays complete for free. The proposed $4 one-time filing layer adds row CSV, print and five local reading summaries, not hidden answers. Checkout is unavailable; the article demo remains unlimited.
Travel-budget arithmetic on reader-supplied prices, distances and economy only, not a quote or a verified fuel offer. Confirm pump prices and plan driving within legal and safe limits; do not use this tool while driving.
What this is built on
Method: Extra round-trip km means the distance added versus the route you would otherwise drive; a station that is merely nearby but not on your path can still add kilometres. Economy should reflect the stop-start or extra-urban character of the detour, taken from your own records. Multiply them together only inside the formula: (km ÷ km/L) × destination price.
All sample records, dates, quantities and labels are invented. No outside policy, contract, rate, clock offset, measurement or accessibility standard is represented as verified.
Google’s official pricing documentation, fetched 2026-10-01, says AI Studio is free in available regions. Optional formatting may require a Google account; manual local entry requires none. Limits can change and free-tier content may be used to improve products. Do not send private records.
Before: the lower board price looked like free money. After: the receipt shows the purchase saving minus the fuel the detour itself consumes.
Setting: Litres to buy at the pump (same in both places) = 40. Expected summary: 3.1925 net currency units.
The Tuesday option saves (1.72 − 1.61) × 40 = 4.40 on the purchase, and the 12 km round trip consumes 12 ÷ 16 = 0.75 L that cost 0.75 × 1.61 = 1.2075 at the cheaper station, netting 3.1925. The weekend option saves only 0.40 but drives 30 km at 12 km/L: 2.5 L × 1.69 = 4.225 of extra fuel, netting −3.825, which the receipt flags. The summary keeps the best net figure, 3.1925, and the flagged row shows a detour that costs money.
Sample B — changed plan
Same road | 1.65 | 1.65 | 5 | 10
Setting: Litres to buy at the pump (same in both places) = 40. Expected summary: -0.825 net currency units.
Identical pump prices mean zero purchase saving, while the five-kilometre detour still burns 0.5 L worth 0.825 at station B. The net is −0.825: the detour has a price even when the cheaper station is not actually cheaper. This boundary keeps the honest negative in the reading instead of flooring it at zero.
Sample C — boundary convention
Next door | 1.80 | 1.75 | 0 | 9
Setting: Litres to buy at the pump (same in both places) = 40. Expected summary: 2 net currency units.
Zero extra kilometres means the detour burns nothing, so the full (1.80 − 1.75) × 40 = 2.00 saving survives. The edge case confirms that a station you pass anyway is pure arithmetic gain under this model — though 'on the way' is a judgment you supply through the zero-km figure, not one the tool verifies.
Optional AI formatting, never the calculation
Manual entry completes this fuel-detour receipt for free without signup. If available to you, the free AI Studio interface linked in the sources may format fictional or non-sensitive notes; external access may require an account. No API key or AI call is built into this tool. Free-tier content may be used to improve products. Review each cell and transcribe it to the labeled row schema; do not paste the JSON object into the row box.
Format only these fictional or non-sensitive notes for a fuel-detour receipt. Return strict JSON shaped as {"rows": [{"label": "string", "cells": ["string", "string", "string", "string"]}], "setting": "string"}. The columns are Option code | price A per litre | price B per litre | extra round-trip km | economy km per litre; the setting is Litres to buy at the pump (same in both places). Keep all supplied strings and quantities exactly; do not calculate, infer missing entries, invent dates or add advice. If any required value is missing, return an empty rows array and ask me for it separately. I will verify every cell against my source and manually transcribe rows using vertical bars before running the local calculator.
An AI response is not executed, fetched or trusted as a result. Missing values remain questions; the strict local parser checks the rows you actually enter.