Live basis→mark bridge and exit dial - so a green candle never pretends to be average-cost bag P&L or settled cash.
Educational average-cost sketch. Mark ≠ basis. Not tax lot software, investment advice, or a brokerage blotter.
By Ahmet C. Toplutaş·Site owner & editor · Blockchain tools
Last updated May 21, 2026 · Reviewed May 21, 2026 · Planning estimates only - not tax, medical, or investment advice
01
Charts shout percent moves. Bags care about what you paid versus what the stack is marked at. Those are different numbers whenever you bought more than once, paid fees, or are staring at a candle that is not measured from your average fill.
Mark is the reference price you choose for “now” - spot, an index, or a conservative exit quote. Basis is average cost per coin across purchase lots (with optional buy fees folded in). Profit and loss live in the gap. Celebrating a +15% day from last week’s local low while your average cost is still above mark is how Twitter P&L and wallet P&L diverge.
This page’s framing is Mark ≠ basis. The panel builds average cost from your lots, draws a basis→mark bridge, and lets an exit dial split paper gains from pocketed (realized) ones - so a green candle is not mistaken for a settled bank deposit.
Traders, long-term holders, and anyone reconciling an exchange CSV hit the same trap in different clothing: the chart’s reference point is not the bag’s cost basis. Naming mark and basis first is the literacy skill; the arithmetic is secondary.
Decision framing: “What did the bag cost on average, and where is it marked?” - not “how loud was today’s percent move?”
02
Each purchase lot is amount × price. Sum the costs, sum the coins, divide - that is average cost basis. A later buy at a higher price lifts the average; a dip buy lowers it. The lot stack shows each lot’s share of total cost so you see which fills still dominate the bag’s economics.
This model uses average cost for both the remaining bag and any partial exit. Many tax systems allow or require other methods (specific identification, FIFO, and so on). Treat the panel as literacy for “what is my bag doing?”, not as a filing engine.
Up to four lots keep the sketch readable and shareable. For dozens of fills, aggregate into a few representative tranches or move to a dedicated portfolio/tax tool.
03
The bridge is the unique visual affordance: average cost and mark plotted on one scale, with $/coin gap and % gap labeled. It answers the Mark ≠ basis question without forcing you to re-read a results table.
When mark sits left of basis, the bag is underwater on average cost even if the last bounce felt euphoric. When mark sits far right, the gap % is your average-cost return - still distinct from “price is up X% from January’s wick.”
Unlike an impermanent-loss ratio ladder or a scientific DEG/RAD mirror, the bridge is a single-asset cost-versus-spot story. It does not model LP inventory or angle units; it models bags.
Read the bridge before the headline number. If the markers sit almost on top of each other, you are near break-even on average cost - regardless of how dramatic the weekly candle looks on a log chart.
04
Unrealized P&L marks the coins you still hold. Realized P&L appears only when coins leave at a settlement price. The exit dial pretends you sold a percentage of the bag at the current mark under average cost, then splits the result into realized (sold) and unrealized (held) cards.
Optional sell fees cut proceeds before realized net is computed. That is why a full 100% exit can still show less than “mark value − invested” when fees are on - pocket ≠ gross mark.
Use the dial for planning (“if I take a quarter off here…”) rather than as a trade ticket. Actual fills, slippage, and on-chain costs will differ; pair with the gas fee calculator when network cost matters.
Try the Partial take-profit preset: watch realized and unrealized cards diverge while the bridge stays anchored to average cost.
05
“ETH is +12% today” says nothing about whether your bag is profitable. Bag P&L compares mark to your basis. A trader who bought higher on leverage liquidations can be red on a green day; a DCA stack can be green while the coin is red versus its all-time high.
Mentally convert headlines into questions: “+12% from which reference, and is that reference my average cost?” If the answer is “from yesterday’s close,” keep scrolling. If you need LP pair risk instead of a single-asset bag, use the impermanent loss calculator.
Another trap: measuring from the all-time high (“I’m still −60% from ATH”) while your personal basis is far below that ATH. ATH drawdown and bag P&L answer different questions; only one of them pays rent.
06
Buy fees increase what you effectively paid per coin (higher basis). Sell fees reduce what you take home (lower realized net). Ignoring both is how spreadsheet P&L looks healthier than the exchange history.
This panel’s fee fields are flat percentages - a sketch, not a venue fee schedule. Maker rebates, withdrawal fees, and network gas sit outside the flat model; add them mentally or with dedicated tools when they dominate small trades.
Educational disclaimer: nothing here is tax, investment, or legal advice. Digital-asset rules vary by country and change. For filing workflows, prefer a crypto tax product or a qualified professional - and see our crypto tax calculator only as a related educational surface, not a substitute for filings.
07
Example A · BTC DCA stack. Preset: 1 coin at $20k and 0.5 at $25k, mark $45k. Basis should land near $21.7k/coin (before fees). Bridge shows a wide positive gap; exit dial at 0% keeps everything unrealized.
Example B · ETH underwater. Preset: 10 ETH bought at $3,200, marked at $2,100. Bridge flips left of basis; net P&L is red even if the last hour was green.
Example C · Partial take-profit. Preset sells 25% at mark. Compare realized net (after sell fee) to unrealized on the remaining 75% - paper ≠ pocket in one view.
Example D · Alt moon bag. Preset: cheap early lot plus a chase lot, mark far above both, 40% sold. Lot stack shows the cheap tranche still dominating cost share while realized captures part of the moon.
After presets, replace lots with your own fills. If the bridge disagrees with the story you told yourself from a chart screenshot, trust the average cost math and update the narrative - not the other way around.
When you share a link with a teammate or future-you, include the exit % you were debating. Reopening the same mark with a blank dial restarts the paper-versus-pocket argument from zero.
08
Most “wrong P&L” screenshots are reference errors: wrong basis, ignored fees, or mixing realized cash with marked inventory.
09
Share links are intentional snapshots of lots, mark, fees, and exit %. Live typing never rewrites the address bar.
10
Stop here for single-asset average-cost literacy and paper-versus-pocket planning. Hand off for LP inventory risk, DCA schedule design, network cost, or tax-lot workflows.
11
Mark is the spot (or reference) price you are using to value the bag right now. Basis is what you paid on average across purchase lots, including optional buy fees in this model. P&L lives in the gap between those two numbers - not in the latest candle’s percent move from an arbitrary entry.
Sum each lot’s coin amount × price (plus optional buy-fee %), then divide by total coins. Later buys change the average. This page uses that average-cost method for both the remaining bag and any partial exit - it is educational, not a jurisdiction-specific tax lot engine.
It plots average cost per coin against the mark on one scale so you see $/coin gap and % gap at a glance. That is the unique literacy affordance here - different from an IL ratio ladder, a gas preset strip, or a DEG/RAD trig mirror.
It pretends you sold a percentage of the bag at the mark using average cost. Proceeds (minus optional sell fee) minus cost of those coins is realized; the unsold remainder stays unrealized. Paper ≠ pocket until something actually settles.
No. It is an average-cost sketch for education. Real brokers and tax rules may require specific-lot identification, FIFO, or other methods, and they track fees, transfers, and wash-sale-like rules differently by country. Use a tax professional or dedicated crypto tax tool for filings.
No. Lots, mark, exit %, and fees hydrate from the URL on load; the address bar updates only when you use Share or Copy.
Bag P&L · Mark ≠ basis
Average-cost sketch across lots. Educational - not tax lot software.
Purchase lots
Exit dial · paper ≠ pocket
0% soldAverage-cost exit at the mark. Remaining coins stay unrealized.
Net bag P&L (realized + unrealized)
$35,000 · +107.69%
Basis $21,667/coin · mark $45,000/coin · 1.5 coins
BASIS → MARK BRIDGE
REALIZED (sold)
$0
0 coins · net of sell fee
UNREALIZED (held)
$35,000
1.5 coins still marked
Lot stack · cost share
Cost $20,000 · lot mark P&L $25,000
Cost $12,500 · lot mark P&L $10,000
Mark ≠ basis
Invested $32,500 · mark value $67,500. A +20% candle from your last fill is not the same as bag P&L versus average cost.
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