Your crypto portfolio started at €1,000 and finished at €1,980. That looks like a 98% gain—until you remember adding another €1,000 halfway through the year. In cash terms, you actually lost €20.
Deposits, withdrawals and movements between wallets can make a balance chart misleading. A useful performance report separates money you supplied from results generated by the investments. You can do this in a spreadsheet without connecting a wallet or relying on an AI-generated explanation.
Start with the question your portfolio report should answer
Three questions require different measurements. “How much money did I make?” calls for a cash gain or loss. “How did my investment strategy perform, independent of contributions?” calls for a time-weighted return. “What return did I personally earn, given when I invested?” calls for a money-weighted return.
For a portfolio without borrowing or other complications, the cash calculation is straightforward: ending value − starting value − contributions + withdrawals. Use one reporting currency throughout. This produces a monetary result, not a percentage return, because it does not account for how long each contribution was invested.
Reporting software may help explain these numbers, but a readable narrative is not proof of a correct calculation. For example, https://www.numevia.io/ advertises financial analysis and report generation. That positioning does not establish crypto wallet connectivity or support for time-weighted returns or XIRR. NUMEVIA’s Terms describe the current build as a front-end demo and state that outputs are not financial advice.
Build the underlying ledger first. At minimum, record each event’s timestamp, asset, quantity, reporting-currency value, fee, source, destination and classification. Keep the original exchange exports and transaction identifiers so you can trace a result back to its records.
Separate investment gains, external cash flows and internal transfers
Define the portfolio boundary before classifying transactions. If your report covers an exchange account, a hardware wallet and a DeFi position, moving assets among those locations is an internal transfer. If it covers only the exchange account, a withdrawal to the hardware wallet crosses that narrower boundary.
An external contribution is value added from outside the measured portfolio. A withdrawal removes value for use elsewhere. Buying bitcoin with cash already inside the portfolio is a trade, not a new contribution. Similarly, selling bitcoin into a stablecoin does not create a withdrawal if the stablecoin remains within the boundary.
- New savings deposited into the portfolio: an external contribution, even if they remain as cash initially.
- ETH moved between two included wallets: an internal transfer; match the outgoing and incoming records.
- Crypto withdrawn to pay a personal bill: an external withdrawal, valued when it leaves.
- Staking rewards earned by included holdings: generally investment income, not fresh investor capital.
For a contribution made in crypto rather than cash, record its market value in the reporting currency at the contribution time. Otherwise, the new tokens can appear to be investment profits. Apply the same valuation discipline to in-kind withdrawals.
Bridging, wrapping and depositing into liquidity pools require extra care. They may change the asset representation without changing the economic value you own. Avoid counting both a receipt token and the underlying claim as separate wealth. Classification for performance reporting also does not determine the transaction’s tax treatment.
Calculate time-weighted return with a two-period example
Time-weighted return, or TWR, separates performance into intervals around external cash flows, then compounds the interval returns. The GIPS Standards Handbook for Firms explains the distinction between time-weighted and money-weighted returns, including external cash flows, valuations and geometric linking. Using these principles in a personal spreadsheet does not make the report GIPS-compliant.
Consider this simplified portfolio, with no withdrawals and all fees already reflected in its values:
- On January 1, the portfolio starts with €1,000.
- By July 1, immediately before a new deposit, it is worth €1,200. The first interval return is €1,200 ÷ €1,000 − 1 = 20%.
- You add €1,000, bringing the post-deposit value to €2,200.
- At year-end, the portfolio is worth €1,980. The second interval return is €1,980 ÷ €2,200 − 1 = −10%.
Link the returns by multiplying their growth factors: (1 + 0.20) × (1 − 0.10) − 1 = 8%. Do not add 20% and −10% to report 10%. Compounded returns operate on changing values.
The strategy’s time-weighted return was positive even though your cash result was negative: €1,980 − €1,000 − €1,000 = −€20. More money was exposed during the losing interval than during the winning one. Both results are correct; they answer different questions.
In a spreadsheet, keep one row per interval with its opening value, closing value before the next external flow, and return. For this simple flow-boundary method, calculate closing value divided by opening value minus one, then multiply all the interval growth factors and subtract one. You need reliable valuations around every external flow; a deposit amount alone cannot supply the missing portfolio value.
Use dated cash flows to measure your personal return with XIRR
A money-weighted return reflects the size and timing of your contributions and withdrawals. Excel’s XIRR function handles irregularly dated cash flows and returns an annualized rate using a 365-day year. It is useful when you invest on different dates rather than at fixed monthly intervals.
Use the investor’s perspective: money committed to the portfolio is negative, and money received back is positive. If measuring an existing portfolio from a chosen start date, enter its opening market value as a negative amount on that date. This represents the capital committed at the start of the measurement window; do not also include its earlier purchase history.
For the example above, put dates in column A and amounts in column B: January 1, −1000; July 1, −1000; December 31, +1980, all in the same year. Then enter =XIRR(B2:B4,A2:A4). The final positive amount represents the portfolio’s ending value, as though you liquidated it on the reporting date. It is not a claim that you actually sold.
Add actual withdrawals as positive entries on their dates. Leave internal transfers out: they neither add to nor return your invested capital. The example’s money-weighted result is negative, consistent with committing €2,000 and finishing with €1,980, whereas its TWR is positive.
XIRR needs at least one positive and one negative cash flow, matching ranges and valid spreadsheet dates. Excel uses an iterative calculation and can fail to converge after 100 attempts. Complex cash-flow patterns can also produce ambiguous results. Investigate errors and implausible rates rather than changing inputs until a desirable number appears. Label the output as annualized, especially when the measured period is short.
Check fees, missing prices and transfer records before trusting the result
For most retail investors, net-of-fee performance is the most useful starting point. Trading fees, network fees and platform charges reduce what you retain. If those costs already reduce the balances used in your valuations, do not subtract them again. A fee paid from outside the measured portfolio needs a consistent treatment that captures both the funding and the cost, rather than ignoring it.
Use one valuation policy across the ledger: a consistent reporting currency, timestamp convention and price source or documented source hierarchy. Crypto trades around the clock, so “end of day” needs an explicit time zone. A stale token quote or a stablecoin valued automatically at €1 can distort the result.
Missing flow-time valuations limit how accurately you can calculate TWR. Daily snapshots may miss a sharp price move before an intraday deposit. Reconstruct values from reliable holdings and historical prices where possible; otherwise label the calculation as an approximation. Do not invent a precise-looking valuation to complete the sheet.
Reconcile asset quantities as well as currency values. Opening units plus purchases, transfers in and rewards, minus sales, transfers out and fees, should explain closing units. Check pending transfers at the reporting cutoff so assets are neither omitted nor counted twice. For illiquid holdings, flag uncertain marks: a displayed price may not be available for your full position.
Use AI to explain verified returns—and check the vendor’s limits
Once the ledger reconciles, AI can help draft explanations, suggest classification checks or summarize why TWR differs from XIRR. It should not decide whether an unexplained transfer is income or silently fill missing prices. Keep calculations reproducible in a spreadsheet or another calculation system you can inspect.
NUMEVIA’s company overview at https://www.numevia.io/about states that users have access to information about AI usage, resource consumption and analytical results, and advertises API integration. These statements offer a starting point for vendor questions, not evidence that it exposes return formulas, supports crypto records or produces independently validated performance figures.
Before delegating reporting, ask whether you can export the input ledger, inspect cash-flow classifications, identify price sources and reproduce the result outside the service. Ask how missing records are flagged and whether generated explanations remain tied to a specific calculation version. Test any candidate tool against a small example with a known answer before trusting a full history.
Share only the data needed for the task; never provide seed phrases or private keys. Your final report should show cash gain or loss, TWR, money-weighted return, the measurement dates and important data limitations. Keeping those measures separate makes it much harder to mistake another deposit for investment success.
