WHP to HP Conversion Chart

Q: What is 400 WHP in crank HP?

On a rear-wheel-drive car at 15 percent loss, about 471 crank horsepower. Front-wheel drive at 12 percent gives roughly 455, and all-wheel drive at 22 percent gives about 513.

Q: What is 500 WHP at the crank?

Roughly 588 HP on a rear-drive car, 568 on front-wheel drive, and 641 on all-wheel drive. Bear in mind that at this output level the true figure is likely a little lower, because drivetrain loss does not scale perfectly with power.

Q: How do you convert WHP to HP?

Divide wheel horsepower by one minus the drivetrain loss. For example, 350 WHP divided by 0.85 gives about 412 crank horsepower on a rear-drive car.

Q: Is a percentage the right way to convert WHP?

It is a reasonable approximation but not strictly correct. Much of the loss is fixed mechanical drag that does not scale with output, so a flat percentage overstates crank power on high-output engines and can understate it on low-output ones.

Q: Why do two dynos give different WHP for the same car?

Inertia dynos calculate power from how fast a drum accelerates and typically read higher. Load-bearing dynos apply controlled resistance and read lower. The difference can approach 10 percent, and neither is faulty.

Q: Does AWD really lose more power than RWD?

Yes. All-wheel drive adds a transfer case and a second axle assembly, both of which absorb power. Typical AWD loss runs 20 to 25 percent against around 15 percent for rear-wheel drive.

Every common dyno figure converted to crank horsepower, with a separate column for each drivetrain layout.

↓ Full chart ↓ Which column to use ↓ How accurate is it ↓ FAQ

WHP to Crank HP

Wheel horsepower (WHP)

Drivetrain

Estimated crank HP

—

A dyno measures power at the wheels. Manufacturers quote it at the flywheel. Converting between the two means adding back what the drivetrain absorbed — and because that loss differs by layout, the same 400 WHP means different things in a front-drive hatchback and an all-wheel-drive saloon.

Formula

Crank HP = WHP ÷ (1 − loss %)

400 WHP on a rear-drive car at 15% loss gives 400 ÷ 0.85 = 471 crank HP.

WHP to Crank HP — Full Chart

Columns show the three common drivetrain layouts. Find your dyno figure in the first column and read across to your layout.

WHP	FWD (12%)	RWD (15%)	AWD (22%)
200	227	235	256
225	256	265	288
250	284	294	321
275	313	324	353
300	341	353	385
325	369	382	417
350	398	412	449
375	426	441	481
400	455	471	513
425	483	500	545
450	511	529	577
475	540	559	609
500	568	588	641
550	625	647	705
600	682	706	769
650	739	765	833
700	795	824	897
750	852	882	962
800	909	941	1026
850	966	1000	1090
900	1023	1059	1154
1000	1136	1176	1282

Which Column Should You Use?

Use the one matching how power reaches the road, not what the badge says. A few cases catch people out:

Front-wheel drive has the shortest path — engine, transaxle, driveshafts. Losses are lowest.
Rear-wheel drive adds a propshaft and a separate differential, so slightly more is absorbed.
All-wheel drive adds a transfer case and a second axle assembly. This is where losses climb sharply.
Part-time four-wheel drive tested in two-wheel-drive mode behaves closer to the RWD column, because the front axle is disengaged.

How Accurate Are These Numbers?

They are estimates, and it is worth understanding why. A meaningful share of drivetrain loss is fixed mechanical drag — bearing friction, gear mesh, oil churn — that does not scale with engine output. If a gearbox absorbs 40 HP, that is 20% of a 200 HP engine but only 8% of a 500 HP one.

The practical consequence: percentage-based conversion tends to overstate crank power on heavily modified cars. A 900 WHP build almost certainly loses less than 15% proportionally, so the true crank figure is lower than the chart suggests.

Dyno type matters more still. Inertia dynos such as Dynojet typically read higher than load-bearing dynos such as Mustang or Dyno Dynamics, and the gap can approach 10%. Two figures from different dynos are not comparable at all, no matter how carefully you convert them.

Using the Chart Sensibly

Treat these as a sanity check rather than a specification. If your car is advertised at 450 HP and dynos at 385 WHP on a rear-drive layout, the chart puts crank power near 453 — close enough to confirm the car is healthy and making its claimed output.

What the chart cannot do is settle an argument about whether one car makes more power than another when the figures come from different dynos on different days. For that, only a back-to-back test on the same equipment means anything.

For a single conversion use our WHP to HP calculator, or the wheel horsepower calculator for the reverse direction. To work out the actual loss when you know both figures, use the drivetrain loss calculator, and see wheel HP vs crank HP for the background.

How this calculator is checked

Chart values use crank HP = WHP / (1 - loss), with 12% for FWD, 15% for RWD and 22% for AWD as representative mid-range figures. These are estimates, not measured constants: a significant portion of drivetrain loss is fixed mechanical drag that does not scale proportionally with engine output, so percentage conversion tends to overstate crank power on very high-output builds. Figures from different dynamometer types are not directly comparable.

Frequently Asked Questions

What is 400 WHP in crank HP?

On RWD at 15% loss, about 471 crank HP. FWD at 12% gives roughly 455; AWD at 22% gives about 513.

What is 500 WHP at the crank?

Roughly 588 HP on RWD, 568 on FWD, and 641 on AWD. At this output the true figure is likely slightly lower, since loss does not scale perfectly with power.

How do you convert WHP to HP?

Divide WHP by one minus the loss. So 350 WHP ÷ 0.85 ≈ 412 crank HP on a rear-drive car.

Is a percentage the right way to convert WHP?

It is an approximation. Much of the loss is fixed drag that does not scale with output, so a flat percentage overstates crank power on high-output engines.

Why do two dynos give different WHP for the same car?

Inertia dynos (Dynojet) read higher; load-bearing dynos (Mustang, Dyno Dynamics) read lower. The gap can approach 10%, and neither is faulty.

Does AWD really lose more power than RWD?

Yes. AWD adds a transfer case and second axle, both absorbing power. Typical loss is 20–25% against around 15% for RWD.

Should I trust my dyno sheet or the manufacturer figure?

Both, for different purposes. The manufacturer figure is crank power under standardised conditions; your dyno sheet is wheel power on that machine that day. Only compare dyno runs on the same dyno.