Solana slots are 250ms now, and every per-block limit came down with them

A faster block is not a bigger one. Solana has just made its blocks arrive more often, and made each of them smaller by exactly as much — which is the part of the change that reaches anyone who has written a compute budget.

What went live, and when

Slot time on mainnet dropped to 250 milliseconds at the epoch 1037 boundary, 05:06 UTC on 18 September 2026. It is the fourth of five steps in SIMD-0525, which walks the network down from 400ms to a 200ms target. The 350ms step landed on 19 August at epoch 1019 and the 300ms step on 25 August at epoch 1023.

A gate that activates before it does anything

The feature gate was pending at epoch 1035, went active at the epoch 1036 boundary, and first applied to block production at epoch 1037. That is not a delay and not a bug: gates under SIMD-0525 take effect one epoch after they activate. Anyone reading the explorer on the day the gate went active would have seen an upgrade that was switched on and changing nothing, and been right both times.

What came down with the slot

Each step scales the per-slot resource limits in proportion, so the per-second execution budget stays roughly where it was. Against the 400ms baseline that means maximum block compute units fall from 60 million to 37.5 million and maximum data and coding shreds per slot from 32,768 to 20,480. A leader still gets four consecutive slots, but the window is now 1.0 second rather than the 1.2 it was at 300ms and the 1.6 it was at the start. An epoch now runs roughly 30 hours instead of about 48, and the Validator Admission Ticket costs 1.0 SOL per epoch, down from 1.6.

The Foundation's own page has not caught up

Solana's upgrade page for reduced slot times still lists the 250ms gate as live on devnet and testnet with a mainnet date “to be determined”, while the changelog of 18 September lists it among the notable mainnet gates. The changelog is the one that matches the chain.

What is left

One step: 200ms, with no announced activation date. Each stage is watched under production load before the next is queued, so the gap between steps is the observation, not the paperwork.