Pega este código en el html de tu página web, está ajustado a 600x800 pixeles, si quieres cambiar esa medida modifica los términos  height="600" (ALTO) width="800" (ANCHO)

CALENDARIO COMBINADO O GENERAL (TODOS LOS CALENDARIOS JUNTOS):

<iframe style="border-width: 0;" src="https://www.google.com/calendar/embed?title=Calendario%20Combinado%20FAV&amp;showPrint=0&amp;mode=AGENDA&amp;height=600&amp;wkst=2&amp;bgcolor=%23FFFFFF&amp;src=vizkayatletismo%40gmail.com&amp;color=%23711616&amp;src=sl8io0gtpvbtpkmtljo441k9n8%40group.calendar.google.com&amp;color=%23182C57&amp;src=rr4b9mj9kdi5j73guq16issjac%40group.calendar.google.com&amp;color=%238C500B&amp;src=sdffu4qq6731n2gh6i19no2pic%40group.calendar.google.com&amp;color=%23AB8B00&amp;src=es.spain%23holiday%40group.v.calendar.google.com&amp;color=%23333333&amp;ctz=Europe%2FMadrid" height="600" width="800" frameborder="0" scrolling="no"></iframe>


CALENDARIO DE PISTA FEDERADA:


<iframe src="https://www.google.com/calendar/embed?title=Pista%20Federada&amp;showDate=0&amp;showPrint=0&amp;showTz=0&amp;mode=AGENDA&amp;height=500&amp;wkst=2&amp;bgcolor=%23FFFFFF&amp;src=rr4b9mj9kdi5j73guq16issjac%40group.calendar.google.com&amp;color=%23B1440E&amp;src=es.spain%23holiday%40group.v.calendar.google.com&amp;color=%23875509&amp;ctz=Europe%2FMadrid" style=" border-width:0 " width="600" height="800" frameborder="0" scrolling="no"></iframe>


CALENDARIO DE PRUEBAS ESCOLARES:

<iframe style="border-width: 0;" src="https://www.google.com/calendar/embed?title=Calendario%20Escolar&amp;showDate=0&amp;showPrint=0&amp;showTz=0&amp;mode=AGENDA&amp;height=500&amp;wkst=2&amp;bgcolor=%23FFFFFF&amp;src=sl8io0gtpvbtpkmtljo441k9n8%40group.calendar.google.com&amp;color=%235229A3&amp;src=es.spain%23holiday%40group.v.calendar.google.com&amp;color=%23875509&amp;ctz=Europe%2FMadrid" height="600" width="800" frameborder="0" scrolling="no"></iframe>


CALENDARIO DE CROSS Y RUTA:

<iframe src="https://www.google.com/calendar/embed?title=Ruta%20y%20Cross&amp;showPrint=0&amp;showCalendars=0&amp;showTz=0&amp;mode=AGENDA&amp;height=600&amp;wkst=2&amp;bgcolor=%23FFFFFF&amp;src=sdffu4qq6731n2gh6i19no2pic%40group.calendar.google.com&amp;color=%23AB8B00&amp;ctz=Europe%2FMadrid" style=" border-width:0 " width="600" height="800" frameborder="0" scrolling="no"></iframe>