What makes the Number of days required for Everest Base Camp differ:
There are a couple of factors that make the number of days for EBC differ from one another. Those include:
Helicopter Return
The popularity of the Everest Base Camp Trek is growing rapidly, and this has made attentive to lots of business entrepreneurs, especially the AIRLINES. With the growing flow of travellers, helicopters are available throughout the mountain.
For travellers who are restricted by time or those who want to skip the same way descent from the Everest Base Camp, they prefer the helicopter option after the Everest Base Camp summit. The very next day or the same day after the Everest Base Camp Trip, one can fly back to Lukla or Kathmandu easily, and this saves 4 Days from the Itinerary. Here, you will trek one way and fly back via Helicopter the other way.
This EBC Trek with Helicopter Return shortens the number of days by skipping the same way descent, and if you follow this itinerary, then the EBC trek can be done in between 7-9 Days with acclimatisation or without acclimatisation, depending upon your fitness level.
Regular Trail to Everest Base Camp, Nepal
The regular Everest Base Camp Trek is one of the most popular and followed trails by travellers. This is a classical route to/from Lukla, and trekkers take the same way to step the EBC and descend. Here, the starting point of the hike and ending point of the hike to EBC remain the same, i.e., LUKLA, a short flight from/to Kathmandu.
If you want to follow the regular and most trusted Itinerary for EBC, then 12- Days Itinerary will be the perfect one, you will get 2 days extra to acclimatise while hiking uphill.

Classic Trail to Mount Everest Base Camp
Classical EBC Trail is comparatively longer in terms of the number of days, and some prefer this route to avoid the Lukla flight. However, due to the excess of roads, one can drive somewhat closer to Lukla to complete the classical route.
If you want to skip the flight option to/from Lukla, then the Classic Everest Base Camp Trail will be the best option. Here, your trek starts from Kathmandu, and you drive to the point below Lukla to commence the hike.
However, for the Classic Everest Base Camp Trek, one will need to spend 14-15 Days in the mountains, making the starting and ending point at Kathmandu.
Physical Fitness of Travellers
The fitness level of travellers is one of the most important parts of the Everest Base Camp Trek. Your fitness level and ability to cope with the high altitude environment will determine how many days you will be able to complete the Everest Base Camp Trek.
However, for senior citizens with their first time at such an altitude, we recommend them to follow the Everest Base Camp Trek for seniors or at least to have a couple of reserve days that you can use while trekking the Everest Base Camp.
These reserve days can be used in times of need and will help your trek to move in a comfortable and flexible way.

What are the important points one should consider for the Everest Base Camp Trek?
Fitness and Pace
Everest Base Camp Trek is 6/7 Hours of hiking every day with some breaks in between. However, one must know that the trek to EBC is uphill in the Himalayas, which will result in a deficiency of Oxygen level. This thin layer of air makes the trek difficult, and your fitness level counts.
So, make sure your itinerary is well designed by a professional and you havethe flexibility to modify at the last hour or during the trek. Hike at a nominal pace and listen to your body and rest as your body demands.
Acclimatization Days
Normally, trekkers heading towards Everest Base Camp use 2 DAYS as an acclimatisation day to make sure their body is balanced with the environment of the Himalayas/high altitude. These acclimatisation days are used only while ascending towards the EBC.
On the third day after the trek starts, they remain
Weather and delay
The weather conditions of the mountain are very uncertain and unpredictable, and Lukla airport, the only gateway to Everest, very often faces the challenges of weather, which leads to delays of the flights for hours to days.
So, travellers also to some extent have to make up their mind with such possibilities and try to be flexible with their itinerary and also the number of days to cover the risk factor if the Lukla flight is delayed due to weather. Some of the travellers have a misunderstanding about the Lukla Flight, so better be prepared for this situation.
The best option if one is out of the scheduled time frame is to skip the extra days in Kathmandu before the trek starts. Some trekkers prefer to spend a day or more in Kathmandu before the Trek starts, and this is sometimes not a good idea. Instead, trek instantly and if everything goes perfectly with the weather, then use the extra days after the trek.
Reserve Day
Having reserve/buffer days apart from the Itinerary will be the best option for any travellers. These reserve days can cover some of the very often occurring situations in the mountain, those includes possibilities of flight cancellation to/from Lukla due to weather and urgent need to extend the Itinerary due to altitude problems.
Some trekkers, despite acclimatisation days, cannot complete the Everest Base Camp Trek because of the thin layer of oxygen. And having a reserve day will help them to use a day or more in the mountains. This will benefit trekkers with high possibilities to complete the trek with some extra days.
What will be the best itinerary to follow for the Everest Base Camp Trek?
If you are looking for a comfortable hike to the EBC Trek, then following 12- Days EBC Regular Itinerary will be one of the best. This provides you with flexibility and you will also get sufficient time of acclimatize at high altitude.
However, if you are a senior citizen with a first time at such an altitude, then 14-Days EBC Trek for Senior Citizens will be the best option to follow.
Can EBC Trek be done in the fastest way?
Everest Base Camp Trek can be done in a short time frame, depending upon travellers’ time schedule. This depends upon how one wants to continue the hike. The shortest version of EBC Trek will be the 7-Day option, and this will be one way Helicopter descend from the Base Camp.
However, if you want to continue both ways tre,k then the 9-Day Everest Base Camp Trek will be another option.

When will be the best time to trek to Base Camp?
Trekking to Everest Base Camp is possible throughout the year. However, there are still some factors that might not be a perfect option for travellers. Those include the unfavourable weather conditions and crowds.
The perfect time with the crystal clear view and less crowd will be from November to February. May and June will also be good time however, there will be trekkers as those are the peak season of the year.
August and September are not highly recommended due to the monsoon, and the possibility of flight cancellation does frequently occur.
Thus, for the best view, trekkers can choose from the second week of OCTOBER till JUNE.

Conclusion:
Everest Base Camp Trek can be done in numerous ways, following a couple of routes one prefer to. This can be done via Airplane to/from Lukla, or drive to/from Lukla or a helicopter option of one-way descent.
Thus, the option one takes determines the number of days for the Everest Base Camp Trek. However, the regular and affordable way to trek to Everest Base Camp is to follow the 12-day itinerary. Further, if one is still restricted by the time frame of the trek, then the Everest Base Camp Trek with Helicopter Return (9-Days) will be a perfect option to follow.