Travel planning guides

Short, checkable answers to the questions the calculators cannot fit on one line — how a gate agent measures a bag, why the return flight takes longer, what a road trip actually costs beyond fuel.

• How much gas for a road trip, and what the fuel number leaves out

  Fuel is the number everyone estimates and rarely the largest one. Here is how to get it right, and what sits underneath it on a multi-day drive.

  Calculator for this: Road trip cost calculator

• How to measure a carry-on bag the way the gate does

  A suitcase is measured with its wheels and handle, not without them. Here is how to take the three numbers, and what the linear inch sum is for.

  Calculator for this: Carry-on size checker