Calc Magica Record - Sayaka vs Tiro Finale

Holy Mami fires a Tiro Finale, which Sayaka deflects away (and shows some impressive regeneration in the process), whcih flies off and causes a colossal explosion. Sayaka Miki is at least 158cm tall (or really, between 158cm and 160cm, but we'll just go with 158cm).
With that, let's find the scale of the explosion. First we scale Sayaka...
435 pixels = 158cm (1.58m)
1 pixel = 1.58m/438 = 0.00360730594m
0.00360730594m X 66 = 0.238082192m

Then from Sayaka's arm to the Tiro Finale...
62 pixels = 0.238082192m
1 pixel = 0.238082192m/62 = 0.00384003535m
0.00384003535m X 341 = 1.30945205m

Next, the Tiro Finale before it vanishes...
13 pixels = 1.30945205m
1 pixel = 1.30945205m/13 = 0.100727081m

Finally, to the explosion.
0.100727081m X 1922 = 193.59745m
193.59745m/2 = 96.798725m
0.100727081m X 1411 = 142.125911m
142.125911m/2 = 71.0629555m

Given we see the fireball itself? We can scale directly to it. Using Nukemap (for a radius of 71.0629555m), we get a result of 610 tons of TNT for our fireball. Alternately, using this alternate nuke calculator, we get a result of 3.16 kilotons.

Final Results
Sayaka deflects a Tiro Finale (low end) = >610 tons of TNT
Sayaka deflects a Tiro Finale (high end) = >3.16 kilotons

Keep in mind that given the Tiro Finale is too small to be seen before it explodes, the explosion would be even higher than this.