Raspberry Pi Official Pi3 Micro USB Universal Power Supply 5.1V 2.5A (White)

You'll need a USB Type C adapter to use this supply for Pi 4

The Official Raspberry Pi Power Supply - Shipped with easily interchangeable heads for the UK, US, EU and Australia you can now use your Pi in all four corners of the world! 

This PSU supports up to 2.5A of current, so it won't let you down when powering hungry devices through your Raspberry Pi 3 Model B

Technical Data

• 5.1V 2.5A Output
• 1.5m Cable
• White with Raspberry Pi Logo
• Input Voltage AC Max: 264V
• Input Voltage AC Min: 90V
• Output Connector: USB Micro
• Output Voltage Nom.: 5.1V
• Interchangeable Adaptor - EU/UK/US/AUS
  
  The below is a copy from https://www.raspberrypi.org/help/faqs/#powerReqs.

  Here is a table comparing the amount of power drawn in amps under different situations:

  		Pi1 (B+)	Pi2 B	Pi3 B (Amps)	Zero (Amps)
  Boot	Max	0.26	0.40	0.75	0.20
  	Avg	0.22	0.22	0.35	0.15
  Idle	Avg	0.20	0.22	0.30	0.10
  Video playback (H.264)	Max	0.30	0.36	0.55	0.23
  	Avg	0.22	0.28	0.33	0.16
  Stress	Max	0.35	0.82	1.34	0.35
  	Avg	0.32	0.75	0.85	0.23

  Test conditions used a standard Raspbian image (current as of 26 Feb 2016),