Inspire » fov

const hFOV = 2 * Math.atan( Math.tan( camera.fov * Math.PI / 180 / 2 ) * camera.aspect ) * 180 / Math.PI; // degrees

horizontal field-of-view

function fovHorizontalToVertical(fovHorizontal, aspect) {
  const fovHorizontalRad = (fovHorizontal * Math.PI) / 180;
  const fovVerticalRad = 2 * Math.atan(Math.tan(fovHorizontalRad / 2) / aspect);
  const fovVertical = (fovVerticalRad * 180) / Math.PI;
  return fovVertical;
}

const fovHorizontal = 50;
const aspect = window.innerWidth / window.innerHeight;

const fovVertical = fovHorizontalToVertical(fovHorizontal, aspect);

camera.fov = fovVertical;
camera.updateProjectionMatrix();