Here's a quick resource for all your graphic design needs!
Facebook:
FB Event image: 1920 x 1080 exactly! (also for TV)
Any other graphic: Square (1080x1080) is best, followed by 4:5 proportion, or 1080 x 1350
Instagram:
Feed post: minimum 1080 width for best quality
Landscape photo size: 1.91:1 proportion, or 1080 x 566.
Portrait photo size: 4:5 proportion, or 1080 x 1350. (Best size for engagement!! Square is better on FB than insta)
Story: 1920 x 1080
Café TV:
1920 x 1080 exactly! (also for FB events)
October 12 - First Lunch and Learn: How to resize on Canva!
Source: louisem.com