Verified formula Updated Jun 2026 Private — runs on your device
Efficiency improvement
25.00%
For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.
The Fuel Efficiency Improvement Calculator works out your efficiency improvement in an instant. Enter old fuel efficiency and new fuel efficiency and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
The Fuel Efficiency Improvement Calculator uses the formula:
Efficiency improvement = (New fuel efficiency - Old fuel efficiency) ÷ Old fuel efficiency × 100
For example, with old fuel efficiency of 12 km/l and new fuel efficiency of 15 km/l, the efficiency improvement is 25.00%.
| Old fuel efficiency | 12 km/l |
|---|---|
| New fuel efficiency | 15 km/l |
| Efficiency improvement | 25.00% |
|---|
Results are estimates for educational use, not professional advice.
Reference table of efficiency improvement for Fuel Efficiency Improvement across a range of old fuel efficiency values — exact, engine-computed figures you can read off at a glance.
Learn how to calculate Fuel Efficiency Improvement — the formula explained step by step, with worked examples and a free calculator to check your answer.