Ld is given by the formula

View attachment 2711
Where phi is the diameter of the bar

Sigma-S is the strength of the bar

Tbd as follows -

For M20- 1.2

For M25-1.4

For M30-1.5

For M35-1.7

For M40 and above-1.9

These Tbd values are for mild steel bars, i.e, Fe250

For HYSD bars, like Fe415 and Fe500 multiply the value given above by 1.6 (or in short we're increasing it by 60% as per codal recommendations)

Therefore, for your question

Sigma S is 415

Tbd is (1.6*1.2)

Plugging in these values into the formula we get the Development length as

Ld=54d

Or Ld=54*25=1350 mm or 1.35m

Hope it's clear.

P. S this formula is available in IS 456:2000,pages 42-43.

Regards.