Crypto Newbie / Simulators / Balancer Weighted
Balancer Weighted Pool Simulator
Uniswap pools are always 50/50. Balancer pools can be any weighting — 80/20, 50/30/20, 25/25/25/25 — across up to 8 assets. The math generalises constant-product to weighted geometric mean: invariant V = ∏Bi^Wi. This simulator runs the Balancer V2 swap formula on a 3-asset pool so you can see how weighting changes spot prices + slippage.
Pool composition
| Token | Balance | Weight |
|---|---|---|
| BTC | ||
| ETH | ||
| USDC |
Pairwise spot prices
Spot price = (Bo/Wo) / (Bi/Wi). Weights skew the price — a token at 80% weight is 'expensive' even with the same balance.
1 BTC =
20.000000 ETH
1 BTC =
50.00k USDC
1 ETH =
0.050000 BTC
1 ETH =
2.50k USDC
1 USDC =
0.000020 BTC
1 USDC =
0.000400 ETH
Swap
Why weighting matters
In a 50/50 pool, the spot price is just balance ratio. In an 80/20 pool, the price formula is (Bo/Wo) / (Bi/Wi) — the weights skew the price even when balances are equal. A token at 80% weight is implicitly 'expensive' relative to its balance; arbitrageurs will keep buying it to push balance lower. This is what makes a Balancer pool self-rebalance — the math FORCES the pool composition back toward the target weights.
Index funds via weighted pools
Want exposure to 50% BTC / 30% ETH / 20% USDC permanently? A Balancer pool with those weights does it automatically. As BTC pumps, arbitrageurs sell BTC INTO the pool (its weight is now above 50%), simultaneously buying ETH + USDC out (now below their weights). The pool stays at target allocation without any active management. Balancer's flagship product (BAL token's 80/20 pool) showed this works at scale.
Slippage on weighted pools
Slippage on a weighted pool scales with both pool depth AND weight ratio. Swapping 1% of an 80%-weighted token barely moves spot price. Swapping 1% of a 20%-weighted token moves it 4× more (because there's 4× less of it relative to its target). This is why imbalanced pools are bad for the underweighted side — small trades cause big slippage on the rarer asset.
When Balancer beats Uniswap and vice versa
Balancer wins: multi-asset pools (index funds, portfolio rebalancing), asymmetric pair pools (80/20 governance/quote), pools where one side has natural illiquidity. Uniswap V2/V3 wins: simple 50/50 pools where the depth and capital efficiency improvements of V3 outweigh Balancer's weighting flexibility. Most DeFi blue chips use Uniswap; treasury portfolios and exotic pairings use Balancer.
Frequently asked questions
+Why are most pools 50/50 if weighted pools are flexible?
Two reasons: (1) Code simplicity — 50/50 has the cleanest x·y=k formula, easier to audit and lower gas. (2) Symmetry — for two tokens with similar volatility (ETH/USDC), 50/50 is the optimal allocation for capital-efficient swap pricing. Weighting only wins when the use case demands it (index, asymmetric exposure).
+What does 'impermanent loss' look like on weighted pools?
Different from 50/50. In a 50/50 pool, IL scales with the price ratio change. In an 80/20 pool, IL is much smaller for movements in the 20%-weighted token (because you hold less of it) but proportionally larger for movements in the 80%-weighted token. The 80/20 ratio is popular for governance tokens precisely because it minimises IL for LPs holding governance tokens long-term.
+Can weights change after pool creation?
On standard Balancer V2 weighted pools: no, weights are fixed at deployment. There's a separate pool type called LBP (Liquidity Bootstrapping Pool) where weights shift on a schedule — used for launches and Dutch auctions. See our LBP simulator for that mechanic.
+Why does the simulator show different prices for A→B and B→A?
It shouldn't, unless I'm misreading the math. They should be reciprocals: if 1 A = X B, then 1 B = 1/X A. The simulator computes both independently via the same spot price formula — if they don't reciprocate exactly, that's a tiny floating-point rounding error. Check the math: yours are reciprocal up to ~10 decimal places.
+Is there a maximum number of tokens in a pool?
Balancer V2 supports up to 8 tokens per weighted pool. Beyond that, gas costs for swaps become prohibitive (each token adds to the invariant calculation). Most production pools use 2-4 tokens. Multi-asset pools with 4-8 tokens are typical for tokenised index products.