Jump — Tnt

Ignite the TNT and wait approximately 3 seconds (or until the 7th-8th white blink) before jumping.

Use a TNT timer mod (if playing on Forge) to see exactly when the TNT will explode. TNT Jump

To help you get the best "piece" (or technique) for your situation, are you working on: to mid? Vertical jumps to reach high bridges? Defensive or counter-offensive jumps in a tight spot? Ignite the TNT and wait approximately 3 seconds

Place a block of Obsidian above your head to minimize taking massive knockback from your own TNT. TNT Jump