When will the migration to Ironwood be complete?

When following the Ironwood migration tracker, you may notice that funds move into Ironwood gradually rather than all at once. Some users have asked whether Ironwood migration needs to reach 100% before we can be confident that no inflation occurred.

The answer is no.

The migration percentage does not verify ZEC's supply. That assurance comes from the protocol itself.

This article explains the difference.

TL;DR

The migration tracker shows how much ZEC has moved into Ironwood, not whether the supply has been verified.
Zcash's turnstile, enforced by the protocol's consensus rules, is what ensures the ZEC supply remains sound.
Migration was always expected to happen gradually as wallets update and users move funds.
Because some coins are permanently inaccessible, the migration will never reach 100%.
A migration below 100% is expected and does not indicate inflation or an exploit.

Why was Ironwood introduced?

Earlier this year, security researchers identified a vulnerability in Zcash's Orchard shielded pool.

The issue was responsibly disclosed, patched before there was any evidence of exploitation, and the fix was deployed quickly across the ecosystem.

Even so, the Zcash ecosystem chose to go further.

Rather than simply patching the vulnerability, the Zcash ecosystem introduced Ironwood as a new shielded pool that provides stronger long-term assurances through formal verification and additional independent security audits.

What does the migration tracker actually measure?

The migration tracker shows how much ZEC has moved from Orchard into Ironwood over time.

It is a useful way to visualize adoption across the ecosystem.

It is not a measure of whether the network has confirmed the total ZEC supply.

In other words, the migration tracker measures adoption, not validation. As wallets upgrade and users naturally spend or migrate funds, more ZEC moves into Ironwood. The percentage reflects how much of the ecosystem has migrated, not whether the protocol has verified the supply.

What actually protects the ZEC supply?

The protocol does. The mechanism responsible is called the turnstile, which is enforced by Zcash's consensus rules.

With Ironwood activated, Orchard became a closed pool. Existing Orchard funds can still leave Orchard, but no new funds can enter it. Every coin moving from Orchard into Ironwood must pass through the turnstile.

Because the protocol enforces these rules at the consensus layer, no more ZEC can leave Orchard than legitimately entered the pool.

In other words:

The migration tracker shows how much ZEC has moved into Ironwood.
The turnstile enforces how much ZEC is allowed to move.

That's why migration progress doesn't guarantee the integrity of ZEC's supply. The protocol already provides that assurance.

Why is migration happening gradually?

A gradual migration was always expected.

Some users update their wallets immediately, while others may not update for weeks or months. Some ZEC is held in long-term storage and may not move for years.

As users naturally spend or migrate their Orchard funds, more ZEC enters Ironwood.

This gradual transition is an expected property of the upgrade.

Why will migration never reach 100%?

It's likely that some Orchard wallets have been permanently lost. Wallets can be lost, recovery phrases discarded, or small balances left behind indefinitely.

If the owner no longer has the keys needed to spend those funds, those coins can never migrate into Ironwood.

This isn't unique to Orchard. Older Zcash shielded pools like Sprout and Sapling still contain funds years after they were superseded.

For that reason, a gradual migration that never fully reaches 100% was always expected.

It does not indicate inflation, an exploit, or a problem with Ironwood.

Does an incomplete migration mean there could be extra ZEC?

No.

The turnstile already prevents more legitimate value from leaving Orchard than existed there.

Even if Orchard never reaches a zero balance, the protocol continues enforcing the supply rules.

A migration percentage below 100% simply means some legitimate Orchard funds have not moved, or never will. It is an expected property of the migration, not a measure of the integrity of ZEC's supply.