Building Power & Flex slips
How Power and Flex slip types differ, what the payout tiers mean, and how SmartStake calculates a slip's expected value before you place it.
Power vs Flex — the core difference
A DFS slip is a bundle of player-prop picks — legs — placed against a payout table published by the DFS site. The two fundamental slip types differ in what happens when some legs miss.
A Power slip is all-or-nothing. Every leg must hit to receive any payout. The reward for that strictness is a higher multiplier: a 5-leg Power slip typically pays 20× on a hit. If even one leg loses, the entire stake is lost.
A Flex slip (sometimes called an Insured, Dynamic Play, or Safety slip, depending on the platform) allows partial misses. Each paying tier maps a hit count to a multiplier. A 5-leg Flex might pay 0.4× if three legs hit, 2× for four, and 10× for all five. You recover something on near-misses, but the top-tier multiplier is considerably lower than the equivalent Power slip. Some Flex tiers pay a multiplier below 1×, meaning you get some money back but still lose on net.
The slip type is set by which slip you select in the Fantasy optimizer before you add picks. The payout table displayed in the slip builder reflects the exact multipliers for your chosen bookmaker and slip configuration.
Break-even probability
Because each leg is a player prop with a 50/50-style over/under structure, DFS platforms implicitly assume each pick has a 50% chance of hitting when they set their multipliers. The actual fair probability for each pick may differ. SmartStake computes the break-even probability — the uniform per-leg hit rate at which the slip's expected return equals your stake (a multiplier of exactly 1×) — using a binary search over the expected-multiplier function. This is shown on each slip in the optimizer table and in the slip builder.
A 5-leg Power slip at 20× breaks even when each leg has roughly a 55% chance of hitting. A 5-leg Flex, with its graduated tiers, breaks even at a lower per-leg probability because the partial payouts contribute value even when not all legs win.
Break-even is not your target
Beating break-even is necessary but not sufficient. You want picks whose true probability exceeds the break-even rate by enough to produce positive EV on the slip as a whole. See how SmartStake estimates that below.
How SmartStake estimates a slip's EV
When your slip is complete — all required legs added — the slip builder displays two summary figures: Chance to win (the probability that all legs hit, computed from the devigged true probabilities of your picks) and Total EV (the slip's overall expected return as a percentage of stake).
The expected multiplier is calculated by iterating over each payout tier. For each tier, SmartStake computes the probability that exactly that many legs hit — using the binomial-style distribution built from each pick's individual true probability — then multiplies that probability by the tier's multiplier. Summing across all tiers gives the expected multiplier for the slip. Total EV is then (expected multiplier − 1) × 100%.
Concretely: if your 5-leg Flex has tiers at 3 hits (0.4×), 4 hits (2×), and 5 hits (10×), SmartStake computes the probability of landing exactly 3, 4, and 5 hits given your picks' true probabilities, weights each by the corresponding multiplier, and sums. An expected multiplier above 1.0 means the slip is positive EV; below 1.0 it is negative. The EV figure in the slip header turns green for positive and red for negative.
Per-leg edge is also shown inline: each pick in the builder displays its individual edge — the difference between its devigged true probability and the slip's break-even probability — as a coloured badge. A positive badge means that pick is pulling the slip toward positive EV; a negative badge means it is dragging it down.
The fair probabilities used here come from the same devig engine as the rest of SmartStake. Which reference books feed those probabilities — and how to switch between Default and Custom sourcing — is covered in Fantasy devig source. For the underlying devig math, see Devigging & fair value.
Taking the slip
Once the last required leg is added, the slip builder unlocks the Add to Bet Tracker button. Confirming records the slip as a tracked wager: the stake, the payout tier table as it existed at that moment, and the expected multiplier SmartStake computed. The Bet Tracker then grades each leg individually as results come in and rolls up the wager to the correct payout tier. If a leg is voided by the DFS platform — shrinking the slip to a smaller size — the tracker surfaces it as needing manual settlement, because the tier table for a different slip size differs from the one snapshot at take time.
For a full walkthrough of the Fantasy tool and how picks are filtered and sorted, see Fantasy optimizer overview. For how progressive lines work within a slip, see Reading progressive lines.
- Odds, prices, expected value, conversion rates, and profit figures shown are estimates based on the last data we retrieved. They can change at any time — confirm the current price at the book before you bet, as odds may move and entry errors can occur.
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