0-60 Calculator

How the 0-60 time calculator works

A 0-60 run has two parts, and different things limit each. At the start the engine can make far more push at the tires than they can put down, so the launch is grip-limited: the most the driven tires can push is their friction coefficient times the load on them. As speed rises, the power needed to keep accelerating at that rate rises with it, and at some speed the engine can no longer spin the tires. From there the run is power-limited, and acceleration fades as the speed climbs.

This 0 to 60 calculator works through both parts. For the launch it uses the load on the driven tires, which changes as the car squats: accelerating moves load from the front axle to the rear, more so the taller the center of gravity is compared with the wheelbase. That helps a rear-wheel-drive car, works against a front-wheel-drive car, and makes no difference to all-wheel drive, which pushes with all four tires. For the power-limited part it uses the effective power that the classic quarter-mile formulas imply. The time bar shows both parts and the 0-30 split.

The second tab works the other way round: from a time you measured on a closed course or a dragstrip it gives the average acceleration exactly, with no assumptions about the car.

What to enter and where to find it

• Flywheel horsepower. Engine power at the crank, as rated or measured on an engine dyno. Convert a chassis-dyno figure first with the whp to hp calculator.
• Race weight with driver. The car as it runs, with fuel and the driver. Track scales are the best source.
• Drive. Which wheels are driven. It decides how much of the car's weight presses on the tires that push.
• Tire grip. The peak friction coefficient between the driven tires and the surface. For ordinary modern street tires on dry asphalt the peak is around 1.00, which is where the calculator starts; summer performance tires reach about 1.1–1.2, and drag radials on a prepared surface more. Older textbook tables, built on the tires of their day, give 0.90 or less, and a dusty or cold surface grips less too.
• Weight on the driven wheels. Optional: the share of the weight on the driven axle with the car at rest on scales. Left blank, the calculator uses 46% on the rear axle for rear-wheel drive and 63% on the front axle for front-wheel drive, the middle of measured passenger cars.

Car acceleration calculator: average g from a measured time

When you already have a time, from a data logger, a timing app or a dragstrip slip, there is nothing to estimate. Average acceleration is the change in speed divided by the time it took. From 0 to 60 mph the change is 88.0 ft/s, so a car that takes 5.20 seconds averages 0.53 g.

One g is the acceleration of a falling object, 32.17 ft/s². A car that averages close to 1 g from a standing start is pushing about as hard as good street tires on dry asphalt allow; most cars average well under half that.

The tab also gives the distance the car would cover at constant acceleration: the average of the start and end speeds times the time. Real cars accelerate hardest early and fade as speed rises, so they cover a little more ground than that. Any pair of speeds works, so you can also check a rolling run between two speeds on a closed course.

The 0-60 formula: grip first, then power

The estimate joins two textbook relationships: the traction limits for each drive layout, as set out in Gillespie's Fundamentals of Vehicle Dynamics, and the constant-power model behind the quarter-mile formulas.

1. Launch, rear-wheel drive: a = μ × g × s ÷ (1 − μ × h/L)
2. Launch, front-wheel drive: a = μ × g × s ÷ (1 + μ × h/L)
3. Launch, all-wheel drive: a = μ × g
4. Speed where power takes over: v* = P ÷ (m × a)
5. Power-limited time from v* to 60 mph: t = m × (v₆₀² − v*²) ÷ (2 × P)
6. 0-60 time = v* ÷ a + t, or simply 60 mph ÷ a when v* is above 60 mph
7. Average acceleration (second tab) = (end speed − start speed) ÷ time

Here μ is the tire grip, g is 9.80665 m/s² or 32.17 ft/s², s is the share of weight on the driven axle at rest, h/L is the height of the center of gravity divided by the wheelbase, m is the mass and P the effective power. For h/L the calculator uses 0.21, the middle of the passenger cars in the NHTSA's database of measured vehicles, where most sit between 0.19 and 0.22. The same data put the static rear share of rear-wheel-drive cars at about 43–56% and the front share of front-wheel-drive cars at 60–65%.

The effective power is the share of flywheel power that, delivered steadily with nothing lost, would give the trap speeds the quarter-mile formulas predict: about 58%. It stands in for everything the model leaves out (drivetrain losses, the engine spending much of the run below its peak power, gear changes, spinning up wheels and rotating parts, air drag), which is why the calculator asks for flywheel horsepower. The quarter mile calculator shows where it comes from. That share was worked out over a whole quarter mile, so it also covers the slow, grip-limited start that this model already counts on its own, and the air drag near the end of a quarter-mile pass, which is much larger than anything a car meets below 60 mph. Both make the estimate err on the slow side once the tires stop spinning.

Its limits. This is a physics estimate, not a measurement. It does not know your gear ratios, whether second gear runs out just before 60 mph, the shape of the power curve, launch rpm, clutch or converter behavior, or how well the driver launches. Boost that takes time to build, very short gearing and very low power all push the real time up. Read the result as the neighborhood of a good run, and use the grip input to see how much of it depends on the launch.

Worked example

Three cases, worked out with the same functions that run the calculator.

Typical 0-60 times by power-to-weight and drive layout

Estimates from the same model for a 3,400 lb car with the typical weight distribution. Three columns use the default grip; the second rear-wheel-drive column uses 1.2, the top of what summer performance tires reach on dry asphalt. A † marks a time that is grip-limited all the way to 60 mph. Where power is high for the weight, rear-wheel and front-wheel drive lose the most to grip and all-wheel drive pulls ahead; as power drops, the layouts close up.

The launch ceiling. A time marked † sits on the ceiling that grip sets: 60 mph divided by the launch acceleration, and more power would not change it. With the default grip, two driven tires can push a rear-drive car at about 0.58 g, a ceiling of 4.7 s, and a front-drive car at about 0.52 g, a ceiling of 5.3 s. All-wheel drive pushes with the whole weight of the car, and its ceiling of 2.7 s is out of reach for every row of the table.

The rear-drive ceiling moves with the tires and with the weight on the rear axle. Summer performance tires, with a peak grip of about 1.1–1.2, raise the launch to 0.66–0.74 g and bring the ceiling down to 3.7–4.2 s, which is why the column at grip 1.2 runs so much quicker at the top. More weight on the rear does the same thing: with 56% of the car on the rear axle instead of 46%, the default grip already gives 0.71 g and a ceiling of 3.9 s. Powerful rear-drive cars on performance tires therefore run quicker than the default column; set the grip and the weight on the driven wheels to match your car.

Read the table for proportions rather than as a list of results. The grip input moves the quick rows a lot and the slow rows hardly at all, which is the point: with plenty of power for the weight, the tires decide the 0-60 time.

Common mistakes

• Comparing with times that use rollout. US magazines start the clock only after the car has rolled the first foot, the way a dragstrip timer does, and by their own accounts that trims about 0.2–0.3 s from a true standing start. The calculator shows that version as well: at the default launch the first foot takes a rear-drive car about 0.33 s and an all-wheel-drive car about 0.25 s. Compare a magazine figure with the rollout result, not with the standing-start one.
• Using wheel horsepower. The effective power is a share of flywheel power. A chassis-dyno figure makes the estimate slow; convert it with the whp to hp calculator.
• Leaving the grip at the default on sticky tires. Performance tires and drag radials on a prepared surface grip well above ordinary tires on asphalt. If the estimate looks slow for a powerful car on good tires, raise the grip value.
• Forgetting the extra shift. If second gear runs out just before 60 mph, a real car loses time to a shift the estimate does not show. Check where each gear tops out with the gear ratio calculator.
• Timing on a slope or with a tailwind. A measured time is only as good as the run. Use a level closed course and average runs in both directions.