Guide 6.3
Beginner, 6 min read. Checked with Scalpel 1.12.8 on .
In short
In LIVE, Scalpel books the real commission Interactive Brokers reports for every fill. In SIM it estimates fees from the plan you pick in Settings > Risk > Commission plan: IBKR Pro Tiered (the default, $0.0035 a share, $0.35 minimum), IBKR Pro Fixed ($0.005 a share, $1.00 minimum), IBKR Lite ($0) or Custom. On Tiered and Custom, SIM also adds the exchange and clearing fees IBKR passes through. Pick the plan your IBKR account is on, so your paper P&L matches what live trading would cost.
Fees are the cost a scalper pays on every single trade, win or lose. A 10c winner on 200 shares is $20 before fees; at two fills of $1.34 each it is $17.32 after them. Over a hundred trades a month that difference decides whether a small edge is an edge at all. Scalpel nets fees out of every realized P&L figure, every R multiple and every Analytics stat, so set the plan before you judge your SIM results.
Before you start
| Plan | Per share | Minimum per order | Cap | Exchange and clearing fees in SIM |
|---|---|---|---|---|
| IBKR Pro Tiered (default) | $0.0035 | $0.35 | 1% of trade value | Added |
| IBKR Pro Fixed | $0.005 | $1.00 | 1% of trade value | Included in the price, not added |
| IBKR Lite | $0 | $0 | None | Not added |
| Custom | Your number | Your number | Your number | Added |
The commission on one fill is the per-share rate times the shares, raised to the minimum, then capped at the percent of the trade's value: min(max(rate x shares, minimum), cap% x shares x price). The cap can pull a tiny order below the minimum, exactly as IBKR does: 1 share at $5 on Fixed costs 5c, not $1.
On Tiered and Custom, SIM adds what IBKR passes through on that plan:
Regulatory fees on sales (tiny on a scalp) are left out on every plan.
Press Ctrl+, (Cmd+, on a Mac) and click Risk. The commission settings sit under SIM commission (per-share).
Open Commission plan and pick the plan your account is on. Picking a plan fills in Comm $/share, Comm min ($) and Comm cap (% of trade) for you.
If your rate differs (Tiered's per-share rate drops as your monthly volume grows), type your own numbers into the three fields. The plan picker shows Custom as soon as they match no plan. Custom adds the exchange and clearing fees like Tiered.
Click Apply. The new plan prices every SIM fill from now on; fills already booked keep the fee they were charged.
What SIM charges for one fill that takes liquidity (a marketable buy or sell):
| Fill | Tiered | Fixed | Lite |
|---|---|---|---|
| 100 shares at $3.00 | $0.67 ($0.35 + $0.02 clearing + $0.30 exchange) | $1.00 (the minimum) | $0 |
| 200 shares at $4.00 | $1.34 ($0.70 + $0.04 + $0.60) | $1.00 | $0 |
| 500 shares at $5.00 | $3.35 ($1.75 + $0.10 + $1.50) | $2.50 | $0 |
| 1,000 shares at $5.00 | $6.70 ($3.50 + $0.20 + $3.00) | $5.00 | $0 |
| 10,000 shares at $0.50 | $52.00 ($35.00 + $2.00 + $15.00) | $50.00 (the 1% cap) | $0 |
A round trip pays twice: buy and sell. So a 500-share scalp on a $5 stock costs about $6.70 on Tiered and $5.00 on Fixed in SIM.
LIVE ignores the plan setting. Each fill's FEE is the commission IBKR reports for it, which arrives a moment after the fill (the column shows a dash until then). Scalpel adds the entry commission to the position and nets both sides out of the trade's realized P&L when it closes.