Engine
Calculate engine torque in lb-ft or Nm from horsepower and RPM, or convert between metric and imperial torque units. Essential for matching transmissions, axles, and clutch packages to your build.
A torque calculator converts between horsepower and torque at a given RPM, or swaps metric torque (Nm) into lb-ft for US spec sheets and parts catalogs. Torque is what you feel leaving a stoplight; horsepower is what sustains acceleration at high RPM — both matter for towing, road racing, and diesel comparisons.
Diesel buyers compare low-RPM torque peaks; sports car owners check whether advertised HP at 7,000 RPM implies realistic twist at mid-range. Tuners use the same formula the ECU and dyno software use to verify logged data.
A good outcome: torque in lb-ft (and optional Nm) at the RPM you care about, without confusing peak torque on the brochure with peak power RPM.
RPM must be greater than zero — the formula divides by RPM.
When converting from HP, use the RPM where that HP was measured or quoted, not an arbitrary idle speed.
Peak torque and peak HP from OEM charts occur at different RPM — converting one peak to the other will not match both brochure lines simultaneously.
Wheel torque at the tires is engine torque multiplied by gearing — this tool is crank/engine math unless you adjust mentally.
Torquelb-ft = (HP × 5,252) ÷ RPM
Rearrange the horsepower formula. Example: 450 HP at 5,500 RPM → T = (450 × 5,252) ÷ 5,500 ≈ 430 lb-ft.
lb-ft = Nm ÷ 1.35582 | Nm = lb-ft × 1.35582
Torque (lb-ft) = (HP × 5,252) ÷ RPM. Example: 450 HP at 5,500 RPM → (450 × 5,252) ÷ 5,500 ≈ 430 lb-ft.
Metric: lb-ft = Nm ÷ 1.35582 and Nm = lb-ft × 1.35582.
Diesel example: 975 lb-ft at 1,600 RPM → about 296 HP at that RPM — huge torque at low RPM is why tow ratings emphasize twist, not brochure HP alone.
GM rates the current 6.6L Duramax in HD pickups at 470 hp at 2,800 rpm and 975 lb-ft at 1,600 rpm. Diesel torque peaks low — that is why the same horsepower number feels different towing than a gas V8. Use the HP-and-RPM mode to see the torque peak match the published curve.
Honda lists the FL5 Civic Type R at 315 hp at 6,500 rpm and 310 lb-ft at 2,600–4,000 rpm. Converting 315 hp at 6,500 rpm gives roughly 254 lb-ft — again, not the same as peak torque rpm, which is a common bench-race lesson when reading spec sheets.
Peak torque and peak horsepower occur at different RPM on almost every engine. Converting HP at 6,500 RPM will not equal the torque peak printed at 3,500 RPM — that is normal, not a broken calculator.
Diesel and turbo engines carry broad torque plateaus; a single RPM point hides the story. For comparisons, use the same RPM on both engines or compare published peaks from OEM charts. Dyno smoothing and correction factors (SAE vs uncorrected) also shift numbers more than most owners expect.
Use the RPM where you care about performance — cruise RPM for towing, peak power RPM for WOT pulls, or the RPM printed next to a spec-line HP figure. The formula requires one RPM at a time.
HP = (torque × RPM) ÷ 5,252. Low RPM torque still makes strong pulling power, but HP rises with RPM. A 900 lb-ft diesel at 1,600 RPM makes less HP than the same torque at 3,000 RPM.
Gearing multiplies wheel torque, not engine torque. Engine torque from this tool is at the crank; axle and transmission ratios change what the tires feel.
Pair this calculator with these related tools in the garage — same session, no signup.