The counting
This is where people go wrong. Safa → Marwah is length one. Marwah → Safa is length two. Continuing that way, the seventh length ends at Marwah.
If you finish at Safa, you have done six or eight and need to correct it. The counter displays along the corridor make this easy to track, use them rather than counting in your head while making dua.
Starting at Safa
Approach Safa reciting Innas-Safa wal-Marwata min sha'a'irillah. Face the Kaaba, say takbir three times, and make personal supplication. Then walk toward Marwah.
Between the two green markers, men perform a light jog. Women walk throughout. At Marwah, face the Kaaba and repeat the takbir and supplication, without the verse, which is recited only at the start.
Practical notes
The corridor is fully air-conditioned and flat, which makes sa'i considerably less demanding than tawaf despite being longer.
There is a separate accessible route for wheelchairs and electric carts running the full length, and a dedicated floor above the main corridor which is far less congested.
Zamzam coolers run the entire length. There is no need to carry water.
Order matters
Sa'i must follow a valid tawaf. Performing sa'i first, or performing tawaf without wudu and then sa'i, means the sa'i does not count and both must be repeated.
Common questions
How do you perform sa'i?
Start at Safa, facing the Kaaba, reciting the verse Innas-Safa wal-Marwata min sha'a'irillah, then say takbir and make supplication. Walk to Marwah, with men jogging lightly between the two green markers. Repeat until you have completed seven lengths, ending at Marwah.
Is sa'i seven times or fourteen?
Seven lengths, which means seven single crossings, not seven round trips. Safa to Marwah is length one and Marwah to Safa is length two. The seventh length ends at Marwah. Finishing at Safa means you have miscounted.
How long is sa'i?
The full seven lengths cover about 3.15 kilometres and take 40 to 70 minutes depending on crowd level. The corridor is flat, marble and fully air-conditioned, which makes it considerably less demanding than tawaf despite the greater distance.
Is there wheelchair access for sa'i?
Yes. A separate accessible route runs the full length of the sa'i corridor for wheelchairs and electric carts, and there is a dedicated floor above the main corridor that is far less congested at every hour.