How it works
Shares after split = old shares × new/old ratio. Total cost basis stays constant; divide by new shares for average basis.
Input definitions
- Shares before split
- Enter the value in the labeled unit.
- Total cost basis
- Enter the value in the labeled unit.
- New shares per split unit
- Enter the value in the labeled unit.
- Old shares per split unit
- Enter the value in the labeled unit.
A worked example
- Shares before split
- 100
- Total cost basis
- 3000
- New shares per split unit
- 3
- Old shares per split unit
- 2
Assumptions & limits
Planning model using the rates, cash flows and periods entered. Examples are illustrative, not market quotes or personalised financial advice. Taxes, inflation and transaction costs are excluded unless explicitly entered.
Sources & review
Maintained by AnsRio. Methods and examples use automated checks; this does not imply independent professional certification.
Method updated 2026-10-18. Content checked against the stated method and examples. Our verification approach.
Common questions
Does a split change total cost basis?
A pure split does not change total basis in this arithmetic model. Cash in lieu, fractional shares and local tax treatment need separate review.
How does Stock split share and cost adjustment work?
Shares after split = old shares × new/old ratio. Total cost basis stays constant; divide by new shares for average basis.
What should I check before using Stock split share and cost adjustment?
Planning model using the rates, cash flows and periods entered. Examples are illustrative, not market quotes or personalised financial advice. Taxes, inflation and transaction costs are excluded unless explicitly entered.