Formula and accounting assumptions
Required shares equal ceil(requested assets × adjusted share supply ÷ adjusted assets). For comparison, the generic downward conversion uses floor of that same ratio. The difference measures the extra share unit required by the withdrawal direction. A separate redemption estimate takes owned shares, multiplies by adjusted assets, divides by adjusted supply and rounds down, bounded by the actual assets entered for the vault.
Worked hypothetical example
With three asset units and two issued share units, withdrawing two assets requires ceil(4 ÷ 3), or two shares. The downward conversion gives one share, which is insufficient for this exact withdrawal. An owner with only one share can model redemption of one asset unit instead. These examples use zero virtual offsets and no fees. Increasing the withdrawal in the scenario table shows when the owner's entered share balance stops covering the modeled requirement.
Interpret the scenarios and limits
The ownership check is accounting coverage, not confirmation of immediate withdrawability. A vault can have queues, strategy illiquidity, pauses, fees or account-specific limits. Virtual offsets are user-supplied modeling choices; the standard does not force every vault to use this formula. The model rejects ownership above issued supply and requests above actual entered assets. Keep asset units and share units separate and use the contract's corresponding preview and maximum functions when evaluating a real integration.