| 30 MPG looks different from a British review | The American MPG option uses a smaller US gallon than UK MPG. | Choose MPG (UK) for imperial figures; 30 US MPG corresponds to roughly 36.03 UK MPG for the same economy. |
| Higher MPG gives lower L/100km and seems backward | MPG measures distance per fuel but L/100km measures fuel per distance. | Recognize the reciprocal relationship; a higher MPG and lower L/100km both signify better efficiency. |
| Calculated L/100km becomes undefined | The source MPG or km/L may be zero, producing division by zero. | Enter a valid positive observed figure and distinguish missing data from a measurement of zero. |
| Trip fuel requirement seems 100 times too large | A distance-per-100-kilometres unit may have been treated as L/km. | Use litres = distance × L/100km ÷ 100 and verify the exact selected source unit. |
| Fuel cost seems suspiciously high | Currency price per gallon was entered into a per-litre input, or distance was duplicated. | Normalize the fuel price to the expected unit and verify whether the distance covers one-way or round-trip travel. |
| US and UK MPG are shown as the same unit | A source label was copied without its regional suffix. | Add MPG (US) or MPG (UK) to exports and reference tables before comparing figures. |
| Two calculators differ at the third decimal place | One uses rounded display factors or rounds intermediate values early. | Compare full definitions, keep sufficient internal precision and round only the final displayed result. |
| Conversion does not match dashboard mileage | Dashboard readings reflect observed driving and can use different averaging windows. | Check the vehicle data definition and compare the same route, fuel, distance and time period. |
| Expected range is greater than practical range | Full nominal tank capacity was used with no reserve or environmental allowance. | Plan using usable fuel, realistic mileage and a safety reserve, and verify station availability. |
| Refuelling stops seem incorrect | The planner may assume an initial full tank or a different usable tank capacity. | Review starting fuel, actual capacity, reserve and journey distance; use route-specific planning for stops. |
| The return trip budget is too low | Only one-way kilometres were entered. | Include the return distance and any detours, or explicitly select a round-trip option where provided. |
| Estimated annual costs do not match receipts | Fuel price, annual distance or driving mix changed from the assumed values. | Update the model with observed receipts, seasonal mileage and actual pump prices. |
| EV result shows a larger number in km/kWh | Distance-per-energy efficiency reverses the scale of kWh/100km consumption. | Compare like with like: higher km/kWh is better while lower kWh/100km is better. |
| EV charging bill is higher than estimate | Charging losses, idle fees or variable tariffs were not included in the idealized calculation. | Estimate wall energy and all applicable tariffs or fees instead of using battery consumption alone. |
| EV and petrol figures are hard to compare | Kilowatt-hours and litres are different energy and volume units. | Compare actual cost per kilometre with consistent prices or use a clearly defined energy-equivalent methodology. |
| CO₂ results differ from a sustainability report | The tool may use approximate direct combustion factors while the report includes upstream lifecycle gases. | Match the fuel factor, activity data, gases and accounting boundary before drawing conclusions. |
| Diesel CO₂ estimate exceeds petrol for equal litres | Different fuels have different indicative CO₂ emitted per litre. | Use fuel-specific factors and compare the same transport activity rather than equal fuel volumes alone. |
| A car labelled hybrid looks unusually efficient | The rating may use a different driving cycle or a plug-in hybrid weighted test. | Confirm whether the result is city, combined, highway or charge-depleting and compare equivalent protocols. |
| Conversion history disappears | Local browser data may have been cleared or private browsing may not retain it. | Export needed figures and review browser storage settings rather than relying on history as permanent backup. |
| Saved conversions appear on only one device | History and favourites are documented as browser-local, not automatically synchronized. | Export or copy important calculations when moving across devices; do not assume account-based sync. |
| Copy button does not add text to clipboard | Clipboard access may be restricted by browser permissions or context. | Allow clipboard access when appropriate or manually select and copy the displayed value. |
| CSV export opens with unexpected separators | Spreadsheet locale settings may interpret delimiter or decimal punctuation differently. | Use a text editor to inspect CSV, then choose correct import delimiter and decimal locale in the spreadsheet. |
| PDF export does not save on mobile | The mobile browser might handle downloads or printing differently. | Check download permissions, files location and browser print-to-PDF features, or use TXT/CSV. |
| Conversion value appears blank after pasting | The input may contain a unit symbol, multiple separators or an unsupported numeric format. | Enter a positive number only and select the unit separately in the tool controls. |
| High decimal precision produces noisy digits | Finite numeric precision can expose rounding artifacts beyond practical measurement accuracy. | Use a sensible displayed precision consistent with your real fuel measurement and avoid false exactness. |
| Calculated vehicle savings seem too optimistic | The compared mileage values may be laboratory ratings from incomparable driving conditions. | Use observed or like-for-like efficiency and test low, average and high consumption scenarios. |
| Fleet budget underestimates total transport expenses | A fuel calculator excludes maintenance, downtime, insurance and other fleet costs. | Keep fuel cost as a separate line and build a broader total-cost model with additional verified inputs. |
| The converter seems unavailable without internet | Offline use may depend on which app resources the browser has already cached. | Load the tool while connected, then verify offline operation in your own device rather than assuming universal caching. |
| Nautical conversion seems inconsistent | Land miles and international nautical miles are different distances. | Use one nautical mile = 1,852 metres and inspect whether the fuel denominator is litres or gallons. |
| My fuel-saving percentage does not match the km/L change | Percentage gain in distance per fuel differs from percentage reduction in fuel for a fixed journey. | Compare litres required over identical distance before calculating percentage fuel savings. |