Tools
Six things bowlers actually need to work out, each on its own page, each free and without a sign-up. They run in your browser and nothing you type is sent anywhere.
There is also a bowling game on the site that models the same physics these calculators describe: oil, friction, rev rate and ball speed, with full ten-frame scoring. It is the quickest way to see why speed and revs have to match.
Scoring, handicap and average are the three numbers that come up every league night and that almost nobody can do reliably in their head. Speed, rev rate and ball weight are the three that come up the moment you start caring about why the ball does what it does.
Each page shows the working rather than just the answer, because knowing that handicap is truncated rather than rounded, or that a spare pays one bonus ball and a strike pays two, is usually the thing you actually wanted.