How to Verify Our Calculations
You should never take a calculator’s word as final — including ours. Every result on this site can be checked independently, and we encourage students and CFIs to do exactly that. Here are five ways to confirm any answer.
1. Manual E6B comparison
The classic check. Take a time-speed-distance, wind-correction, or fuel-burn problem and work it on a physical E6B (or your favorite manual whiz-wheel). Solve the same problem in the calculator and compare. Small differences are normal — an analog E6B is only readable to a couple of significant figures — but the answers should agree to within the precision you can read off the wheel. Our Digital E6B mirrors the same operations as the manual computer.
2. POH cross-reference
For performance and weight & balance, the authoritative answer is in your aircraft’s Pilot’s Operating Handbook. For example, with a Cessna 172S you can open Section 5 (Performance) and Section 6 (Weight & Balance) and read the density-altitude takeoff-distance tables and the loading arms directly. Compare the POH figure to the calculator’s. Remember that our built-in aircraft profiles use representative published values — your specific airplane’s weighing record is always the final word.
3. Formula reproduction
Every calculator page shows the formula it uses, and the Calculation Methodology page names the source behind it — with full editions and effective dates listed on the Sources & References page. Reproduce the formula by hand or in a spreadsheet, plug in the same inputs, and you should get the same result. This is the most rigorous check — and a great ground-school exercise.
4. Known-value validation
Below are test cases with known-correct answers — the same values we lock into our automated regression tests. Plug them into the linked calculator and confirm you get the expected result.
| Calculator | Inputs | Expected result |
|---|---|---|
| Density Altitude | 5,000 ft elevation, altimeter 29.72 inHg, OAT 35 °C | ≈ 8,836 ft density altitude |
| Crosswind | Runway 27 (270°), wind 300° at 20 kt | 10 kt crosswind (from the right), 17 kt headwind |
| Crosswind | Runway 18 (180°), wind 090° at 15 kt | 15 kt crosswind (from the left), 0 kt headwind |
| True Airspeed | IAS 120 kt, pressure altitude 8,000 ft, OAT 0 °C | ≈ 137 kt true airspeed |
| Weight & Balance (C172S) | Cessna 172S station arms | Front seats 37.0″, rear seats 73.0″, fuel 48.0″ (per POH) |
5. Cross-calculator check
Several tools overlap, which lets them check each other. The Digital E6B time-speed-distance tab should match the standalone Time-Speed-Distance calculator; the E6B density-altitude tab should match the standalone Density Altitude calculator. If two independent paths give the same answer, that is strong evidence the math is right.