Travel Time Reference: Speed Presets, Block Time, and Buffers

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By Bikash Roy

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Bikash Roy

Online Research Specialist · SEO Strategist · Web Developer

Bikash personally verifies every calculator against official standards (WHO, NIH, government data). Online research specialist, SEO strategist, and web developer with 10+ years building accurate digital tools.

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· August 16, 2026

Both modes of the travel time calculator run on two short formulas. What makes the answers useful or useless is the values you feed them. This page defines each input and says where it comes from.

Driving inputs

Drive Time = Distance ÷ Average Speed

Distance here is road distance — what a navigation app reports for the route, not the straight line between two points. The difference is not small: on a route following a coastline or crossing a mountain range, road distance can exceed straight-line distance by half again.

Average speed is the input that carries all the uncertainty, because it has to absorb every stoplight, merge, and speed-limit change across the whole trip in one number.

The word average is doing heavy work. A highway preset of 67.5 mph does not mean you drive 67.5 mph — it means the whole trip, including slow sections, averages out near there. That is why the presets sit below the posted limit on the roads they describe.

Custom speed exists for routes that do not fit one category cleanly: mostly interstate with a slow stretch through a town, or a rural highway with lower limits than a true interstate.

Flight inputs

Block Time = (Distance ÷ Cruise Speed) + Buffer

Distance for flights is the great-circle distance — the shortest path over the curved surface of the earth — not road distance and not the exact path the aircraft flies.

Cruise speed is the airspeed held once the aircraft has finished climbing and levelled off.

Cruise speed is not a fixed property of an aircraft. The figure that matters for arrival time is groundspeed, which is airspeed plus or minus the wind the aircraft is flying through. That is why the same aircraft on the same route can post noticeably different times in each direction.

Buffer is everything that is not cruise: taxiing to the runway, waiting for takeoff clearance, climbing, descending, and taxiing to the arrival gate.

Block time, and why it is the right number

Block time is the airline term for gate-to-gate duration: from pushback at the origin gate to arrival at the destination gate. It is what appears in a published schedule, and it is always longer than pure flying time.

The gap matters far more on short flights than long ones. A 300-mile hop is 36 minutes of cruise at 500 mph, but 66 minutes of block time once the buffer is added — the buffer is 45% of the trip. On a 1,500-mile flight the same 30 minutes is 14% of the total. The article on common travel time mistakes covers what goes wrong when this gets skipped.

Even block time is not the whole journey. It measures gate to gate and says nothing about getting to the airport, clearing security, or reaching your final destination after landing — which is the subject of the flight day planning guide.

Terms in one place

Great-circle distance — the shortest path between two points on a sphere. Flight distances are quoted this way.

Groundspeed — how fast the aircraft moves relative to the ground. Airspeed adjusted for wind. This is what determines arrival time.

Taxi-out / taxi-in — time between gate pushback and wheels-up, and between wheels-down and arriving at the gate. Both sit inside the buffer.

Air time — wheels-up to wheels-down. Between cruise time and block time in size, and the figure most often confused with both.

Elapsed day — the full time a trip consumes, including stops on a drive or ground time either side of a flight. Always the largest number, and the one that actually constrains a schedule. The road trip time planning guide shows how far it diverges from drive time on a long day.

What neither model includes

• Driving: traffic congestion, construction, weather, and any stop you make. The presets assume normal movement when you are moving, not that you never stop.
• Flying: winds aloft, air traffic control delays, ground holds, de-icing, and layover time on connecting itineraries.

Both are planning estimates. Use them to compare options and budget a travel day; check a live navigation app or the airline’s published schedule before anything depends on the exact number.