Nemesis works out position size, risk and reward from your entry and your stop, so the numbers are settled before the order goes on rather than after.
Free on the App Store

Entry, stop, target and balance in. Quantity, notional, risk and reward ratio out.

Work out an averaged entry across multiple price levels before you commit to the first one.

Every safety order laid out, with the averaged entry, take profit and total risk.

Save the setups you trade most and load them without retyping the same values.

Live prices and balance from your own account, so the sizing is against real numbers.