Singapore has the most powerful passport in the world and New Zealand lags behind ranked at number seven, according to the latest index.
The Passport Index Global Passport Power Rank calculates the number of countries that holders of passports can enter either visa-free or by gaining a visa on arrival.
People carrying New Zealand passport can easily enter 153 countries, the same as Australia and Greece.
But it falls behind Malaysia (154), United Kingdom (156) and Germany (158).
Singapore climbed to the top spot after Paraguay removed visa requirements for those carrying Singapore's passport, which means holders can easily enter 159 countries.
The index was developed by Canada-based international residence and citizenship advisory firm Arton Capital.
It is an online tool that ranks the world's passports by their cross-border ease of access.
Philippe May, managing director of Arton Capital's Singapore office, said the ranking "is a testament of Singapore's inclusive diplomatic relations and effective foreign policy".
The US passport had fallen since President Donald Trump took office, according to Arton Capital.
"Most recently Turkey and the Central African Republic revoked their visa-free status to the US," it said.
This left the US with a score of 154 and an index ranking of sixth, the same as Malaysia, Ireland and Canada, and behind 18 other passports.
Afghanistan is at the bottom of the index with a score of 22.
Top 10 Passports:
1. 159 - Singapore
2. 158 - Germany
3. 157 - Sweden, South Korea
4. 156 - Denmark, Finland, Italy, France, Spain, Norway, Japan, United Kingdom
5. 155 - Luxemburg, Switzerland, Netherlands, Belgium, Austria, Portugal
6. 154 - Malaysia, Ireland, Canada, United States of America
7. 153 - Australia, Greece, New Zealand
8. 152 - Malta, Czech Republic, Iceland
9. 150 - Hungary
10. 149 - Slovenia, Slovakia, Poland, Lithuania, Latvia
