Runway Length Requirement Calculator

Work out runway length requirement instantly with clear inputs, formula shown and shareable results.

About Runway Length Requirement Calculator

The runway you need is the longer of the take-off and landing requirements, adjusted for slope (about +5% of take-off distance per 1% of upslope) and then increased by a planning margin. Reporting which case governs tells you whether take-off performance or braking performance is the limiting factor for the runway.

Formula

Runway length

Required = max(TODR x (1 + 0.05 x upslope%), LDR) x (1 + margin%)

Worked example

With the default values below, Runway Length Requirement Calculator returns Runway length required of 1,060.90. Change any input above and every figure here is recalculated in your browser.

Inputs used

Take-off distance required: 900 m
Landing distance required: 700 m
Runway upslope: 0.5 %
Planning margin: 15 %

Results

Runway length required: 1,060.90 m
Governing case: Take-off case governs
Slope-adjusted take-off distance: 922.50 m
Margin included: 138.40 m

Step by step

1Values used
2Runway length
3Runway length required= 1,060.90 m
4Governing case= Take-off case governs
5Slope-adjusted take-off distance= 922.50 m
6Margin included= 138.40 m

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

Frequently Asked Questions

Why does upslope matter more for take-off?

On take-off the aircraft must accelerate against gravity for the whole roll, so a 1% upslope typically adds around 5% to the distance. On landing an upslope actually helps deceleration.

Should I use the same margin for both cases?

A single planning margin is fine for a first pass, but certified operations apply separate factors to take-off and landing distances.