Delta is the most important number when selecting your credit spread strikes. It simultaneously tells you your probability of profit, expected credit, and risk profile. Get this right and everything else falls into place.

Delta Refresher for Credit Spreads

For a bull put spread, you're looking at the delta of your short put. A -0.20 delta (20-delta) put means there's roughly an 80% chance the stock will be above that strike at expiration.

For a bear call spread, you look at the short call's delta. A 0.20 delta (20-delta) call means an 80% chance the stock stays below that strike.

Higher delta = closer to the money = more premium = lower probability of profit.

The Delta Spectrum

| Short Strike Delta | POP (approx) | Typical Credit (% of width) | Best For | 10 delta90%10-15%Ultra-conservative, large accounts 15 delta85%18-22%Conservative income 20 delta80%23-28%Most traders' sweet spot 25 delta75%28-33%Aggressive income 30 delta70%32-38%High credit, higher risk | 40 delta | 60% | 40-50% | More directional bets |

Why 20 Delta Is the Sweet Spot

At 20 delta, you're collecting enough premium to have positive expected value while maintaining a win rate that prevents devastating losing streaks.

The math at 20 delta on a $5-wide spread:

  • Credit: ~$1.25 (25% of width)
  • Max loss: ~$3.75
  • Win rate: ~80%
  • Expected value per trade: (0.80 × $125) - (0.20 × $375) = $100 - $75 = +$25

    • The math at 10 delta on a $5-wide spread:

  • Credit: ~$0.60 (12% of width)
  • Max loss: ~$4.40
  • Win rate: ~90%
  • Expected value per trade: (0.90 × $60) - (0.10 × $440) = $54 - $44 = +$10

    • The 20-delta spread has 2.5× the expected value per trade.

    The math at 30 delta on a $5-wide spread:

  • Credit: ~$1.65 (33% of width)
  • Max loss: ~$3.35
  • Win rate: ~70%
  • Expected value per trade: (0.70 × $165) - (0.30 × $335) = $115.50 - $100.50 = +$15

    • Thirty delta actually has lower expected value than 20 because the loss rate increases faster than the credit.

    Adjusting Delta for Market Conditions

    High VIX (above 25): Sell further out of the money — 15 delta instead of 20. Premiums are elevated so you still collect good credit, and the extra distance protects against the increased volatility.

    Low VIX (below 15): You may need to go to 25-30 delta to collect enough premium. Or skip the trade entirely — thin premiums mean thin edges.

    After a selloff: Implied volatility spikes during selloffs. Selling 15-delta spreads during a correction captures fat premiums with more distance from the stock price.

    Before earnings: Delta behaves differently when binary events are priced in. A 20-delta option on an earnings stock can move to 50-delta overnight on a gap.

    Delta and Time to Expiration

    Delta isn't static — it changes as expiration approaches.

    At 45 DTE: A 20-delta option is comfortably far from the money with lots of time value.

    At 10 DTE: That same 20-delta is closer to the money in absolute dollar terms. Gamma is higher, meaning small price moves change your delta rapidly.

    This is why most traders sell at 30-45 DTE with 20 delta rather than at 7 DTE with 20 delta. The position is "safer" with more time because gamma is lower.

    Portfolio-Level Delta Management

    If you're running multiple credit spreads simultaneously, track your aggregate portfolio delta. Five bull put spreads each at 20 delta doesn't mean your portfolio delta is 20 — it means you have significant bullish exposure.

    Diversify by direction:

  • 3 bull put spreads on stocks you're bullish on
  • 2 bear call spreads on stocks you're bearish on

    • This keeps your net portfolio delta closer to neutral so a broad market move doesn't hit all positions simultaneously.

    OptionsPilot displays your aggregate delta across all open positions, making it easy to balance directional exposure and avoid overconcentration.