One person hauling a 200-pound engine onto a truck bed is a back injury waiting to happen — unless a block and tackle shares the load across rope segments. A pulley system's mechanical advantage equals the number of rope segments supporting the moving block: with 4 segments, the 200-pound engine feels like 50 pounds of pull (plus friction). The trade-off is distance: you must pull 4 feet of rope to lift the engine 1 foot, because work — force times distance — is conserved.

Sailors, tow-truck operators, rock climbers, and theatrical riggers live by this exchange of force for distance. A gun tackle (2 segments) doubles your strength; a luff tackle (3 segments) triples it; a two-block purchase (4+) handles engines and masts. The ideal formula ignores friction — real systems lose roughly 5–10% per sheave, so a 4-segment rig in practice feels more like 60 pounds than 50. This calculator applies the ideal formula: type the load weight in the Variable A box — 200 for the engine — and type 1 ÷ segments in the Variable B box (1 ÷ 4 = 0.25). The Result box shows 50 pounds of ideal effort. Add ~10% per pulley on paper for a realistic estimate.

With the pre-filled defaults — Variable A 10, Variable B 5 — the Pulley Calculator returns Result 50.0000. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.