The bonding curve formula#
A pump.fun coin on the curve trades against virtual reserves: it starts as if the pool held 30 SOL and 1,073,000,000 tokens. The product of the two, k = 30 × 1.073B, never changes during curve trading. Every buy adds SOL to one side and removes tokens from the other so that the product stays k:
- SOL that reaches the curve: c = SOL sent ÷ (1 + fee). The fee is about 1.25% on the curve, so 1 SOL sent puts 0.9877 SOL into the curve.
- Tokens out = token reserve before − k ÷ (SOL reserve before + c).
- Spot price (SOL per token) = SOL reserve ÷ token reserve.
- Market cap = spot price × 1,000,000,000 total supply × SOL/USD.
Only 793.1 million of the billion tokens are sold on the curve. When those are gone the virtual SOL reserve is 30 × 1.073B ÷ 279.9M ≈ 115.005 SOL, which means about 85 SOL of real buys have gone in, and the coin graduates to its PumpSwap pool. The curve-stage explainer, how the pump.fun bonding curve works, covers the mechanics in prose; this page is the arithmetic.
Worked examples at different points on the curve#
The same order buys a very different share of the coin depending on where the curve is. Market caps below are in SOL so they do not depend on the SOL price; multiply by your SOL price for dollars (at $150, 28 SOL is about $4,200).
| SOL already in the curve | Curve progress (tokens sold) | Market cap | SOL to buy 1% of supply | Largest buy under 15% impact |
|---|---|---|---|---|
| 0 (launch) | 0% | 28 SOL | 0.29 SOL | 4.56 SOL |
| 20 | 54.1% | 78 SOL | 0.80 SOL | 7.59 SOL |
| 60 | 90.2% | 252 SOL | 2.62 SOL | 13.67 SOL |
| 80 | 98.4% | 376 SOL | 3.94 SOL | 16.71 SOL |
| ≈ 85 (complete) | 100% | 411 SOL | — | — |
Swipe or scroll to compare all columns.
Two things stand out. First, progress is measured in tokens, not SOL: 60 SOL is 71% of the way to 85 SOL but has already sold 90% of the curve tokens, because each later SOL buys fewer tokens. Second, the impact ceiling grows as the curve fills. Impact is your average fill price against the spot price before the order, and on a constant-product curve that works out to c ÷ the SOL reserve. At launch the reserve is 30 SOL, so anything above about 4.5 SOL into the curve crosses 15%.
One SOL at launch, for example: 0.9877 SOL reaches the curve, buys 34.2M tokens (3.42% of supply) at an average price 3.29% above spot, and moves the spot price itself up 6.7%, from a 28.0 SOL to a 29.8 SOL market cap. The spot move is roughly twice the impact because your average price sits about halfway between the before and after prices.
What this means on a Fullport account#
Fullport prices every curve-stage order from a fresh read of that coin's curve account, using the pump.fun SDK's own buy math, and rejects any order whose impact would exceed 15% with IMPACT_CAP (rules). The calculator's impact figure is the same quantity, so the "largest buy under 15%" column is a good guide to what will be accepted. In practice, keep some margin: the curve moves between your preview and the fill, and your own earlier buys on the same coin are subtracted from the reserves before quoting.
Fills also charge Fullport's 1% platform fee and a modeled network fee, itemized on every receipt (fill policy). To size the trade against your drawdown rather than against the curve, use the position size calculator. Curve-stage coins are tradeable from launch in the terminal and through Fullport Tap on the terminals you already use.
It models one buy against a quiet curve. Real launches have dozens of buyers in the same second, sell pressure, and pump.fun fee changes over time; enter the current fee if it differs. Treat the output as the arithmetic of the curve, not a forecast of the price.
Quick answers
- How do I calculate how many tokens I get on pump.fun?
- Take the SOL you send, remove the venue fee (divide by 1.0125 at a 1.25% fee), add it to the curve's virtual SOL reserve, and divide k = 30 × 1.073 billion by the new SOL reserve. The drop in the token reserve is what you receive. One SOL at launch buys about 34.2 million tokens.
- How much SOL does it take to buy 1% of a pump.fun coin?
- It depends on how far along the curve the coin is. At launch about 0.29 SOL including the 1.25% fee buys 10 million tokens, 1% of supply. With 60 SOL already in the curve the same 1% costs about 2.62 SOL, and with 80 SOL in it costs about 3.94 SOL.
- How is price impact calculated on the pump.fun bonding curve?
- Impact is your average fill price compared with the spot price just before your buy. On a constant-product curve that equals the SOL reaching the curve divided by the virtual SOL reserve, so 0.99 SOL into a fresh curve with 30 SOL of virtual reserve is about 3.3% impact.
- Why does pump.fun curve progress not match the SOL raised?
- Progress counts the share of the 793.1 million curve tokens sold, and each SOL buys fewer tokens as the price rises. So the first 20 SOL sells about 54% of the curve tokens, and 60 SOL has already sold about 90% of them while being only 71% of the roughly 85 SOL needed to graduate.