OBSERVED BASIS · ENTERED CARRY · RESIDUAL
Explain a quote difference without pretending to know fair value
The tool starts with a synchronized spot and futures quote pair. It then applies your simple annual financing, storage, insurance and convenience-yield assumptions over the selected days, adds the two transaction costs and leaves the arithmetic residual visible. The residual is a description of your inputs, not a forecast or arbitrage signal.
This worksheet decomposes an observed quote difference into entered time-carry assumptions and execution costs. It does not decide what the basis should be or turn the residual into a trade.
Keep the quote pair and time window explicit
Use the same currency, unit and observation time.
Separate costs from the convenience yield input
Rates are simple annual inputs, not market-implied estimates.
Add the two quote-side costs separately
Use zero when the cost is unknown; do not hide it inside the rate.
READ THE RESULT
Carry decomposition is a reconciliation worksheet
A positive modeled carry does not prove that the futures quote is expensive, and a negative residual does not prove that a trade exists. Financing terms, storage contracts, insurance, convenience yield, liquidity, taxes, margin, delivery rules and measurement timing may not be represented by the simple inputs. Use the result to document assumptions and ask which evidence is missing.