Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.

Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.

Automotive Calculators

Power-to-Weight Comparison Calculator

2026-09-27 6 min

Head-to-head power-to-weight ratios and the advantage gap.

Power-to-Weight A: 57.14 hp/1000lb
Power-to-Weight B: 83.33 hp/1000lb
Advantage (B-A): 26.19 hp/1000lb; positive = B stronger

Calculator

Horsepower — A(hp)

Weight — A(lb)

Horsepower — B(hp)

Weight — B(lb)

Results update live as you type

Live statistics

Power-to-Weight A

57.14 hp/1000lb

Power-to-Weight B

83.33 hp/1000lb

Advantage (B-A)

26.19 hp/1000lb

positive = B stronger

Results

Optimal

Power-to-Weight A

57.14hp/1000lb

Power-to-Weight B

83.33hp/1000lb

Advantage (B-A)

26.19hp/1000lb

positive = B stronger

Planning estimate from standard automotive formulas. Validate with dyno, timeslip or datalog data when precision matters.

Visualizations

Results overview

57.1Power-to-Weight A

83.3Power-to-Weight B

26.2Advantage

Advantage (B-A) vs. Horsepower — A

Advantage (B-A)

26.2hp/1000lb

060

Formula

The bench-racing settler — power normalized by mass for both cars.

P:W = hp/weight x 1000; advantage = P:WB - P:WA

Alternative Form

Weight-to-power (lb/hp) is the inverse view some classes use

Variables

Symbol	Name	Unit	Description
P:W	Power to weight	hp/1000lb	Acceleration potential index
Adv	Advantage	hp/1000lb	Gap favoring B when positive

Explanation

Higher P:W wins drag races at similar grip — weight erases headline horsepower fast.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Record the inputs.

Horsepower — A:200 hp

Weight — A:3500 lb

Horsepower — B:300 hp

Weight — B:3600 lb

Result: 4 inputs ready

Step 2

Apply the formula.

P:W = hp/weight x 1000; advantage = P:WB - P:WA

Result: Primary result = 26.19 hp/1000lb

Step 3

Read every derived output.

Power-to-Weight A:57.14 hp/1000lb

Power-to-Weight B:83.33 hp/1000lb

Advantage (B-A):26.19 hp/1000lb

Result: Advantage (B-A) = 26.19 hp/1000lb

Final Answer

57.14

Worked Examples

See how the calculator works with different scenarios.

Scenario

Light underdog versus heavier powerhouse.

Inputs

A:200 hp, 3,500 lb

B:300 hp, 3,600 lb

Calculation

57.1 vs 83.3; advantage +26.2

Result

B leads by 26.2 hp/1000lb.

Interpretation

Decisive B edge — A needs gearing or grip to compensate.

Understanding Your Result

Your Result: Power-to-Weight A: 57.14 hp/1000lb

Typical range: Gaps under 5 are close; 15+ is a different league.

What This Means

Normalized punch gap between two cars.

Why It Matters

Settles bench racing with the ratio that predicts straight-line pace.

Professional Interpretation

Treat the primary result as a planning estimate, then validate on a dyno, at the track, or with logged sensor data. If measured numbers disagree by more than ~10%, re-check inputs (units are the usual culprit) before changing parts.

Recommendations

•Double-check units on every input before trusting the result
•Compare against the worked example below to sanity-check magnitude
•Validate with measured data (dyno, timeslip, datalog) when it matters

Learn — fuel economy, deeply

Power-to-weight comparison crowns the true straight-line favorite.

1 · Where the gallon goes (energy path)

Engine heat

60–70% lost

Coolant + exhaust carry most energy away. Hybrids recover some via Atkinson cycle + regen.

Driveline

5–15% lost

Transmission, differential, accessories. CVTs and 8–10 speed autos lose less.

Aero drag

∝ v²

Doubles from 55→78 mph. Roof boxes hurt more than trunks.

Rolling + brakes

10–20%

Tires, weight, stops. Regen braking (hybrid/EV) reclaims city braking energy.

4 · Measure like a pro (the 3-tank protocol)

Fill to first click at the same pump, record the odometer (Tank 0).
Drive normally for 2–3 tanks; always refill to first click at the same pump.
MPG = total miles ÷ total gallons across all tanks — averaging kills pump-click noise.
Cross-check with the trip computer; a persistent >10% gap means the computer needs calibration — or the car needs service.
Log with an OBD-II dongle for per-trip MPG if you want to isolate commute vs. highway behavior.

Practical Tips

•Use race-ready weights with driver
•Same hp standard both sides
•Aero dominates past ~100 mph

Common Mistakes

Mixing units (inches with mm, psi with kPa)

Convert every input to the unit shown on its field before calculating.

Trusting a single output blindly

Cross-check with the worked example and, when it matters, a dyno or datalog.

Assumptions

This calculator makes the following assumptions to provide estimates:

Steady-state model: Formulas assume stabilized conditions; transients, heat soak and traction limits are excluded.

Standard factors: Empirical constants (BSFC, VE, drivetrain loss) use typical values — your combination may differ.

Limitations

Be aware of these limitations when using this calculator:

Estimate, not measurement: Predictions carry real-world scatter of roughly ±5–15% depending on the model.

No transient effects: Shift time, wheelspin, spool lag and heat soak are not modeled here.

Frequently Asked Questions

Answers to common questions about this calculator.

Does higher P:W always win?

In a straight line with equal traction, usually — but grip, gearing, aero and driver decide close gaps.

Curb or race weight?

Race weight with driver and fuel for predictions; curb for brochure comparisons.

Related Calculators

Explore more calculators related to this topic.

Related Guides

Deepen your understanding with these educational resources.

Automotive Guides

Build planning, measurement protocol and validation how-tos

Glossary

Technical terms used in mortgage calculations explained in plain language.

MPG: Miles per gallon. Distance travelled per gallon of fuel; higher is better. US gallon = 3.785 L.
L/100 km: Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.
MPGe: Miles per gallon-equivalent. EV metric: miles travelled on 33.7 kWh (energy of 1 gal of gasoline).
CAFE: Corporate Average Fuel Economy — US fleet-average efficiency standard enforced by NHTSA.
Rolling resistance: Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.
Aerodynamic drag: Air resistance growing with the square of speed — why highway MPG falls fast above 60 mph.
Hypermiling: Driving techniques (coasting, steady speed, anticipation) that maximise real-world MPG.
OBD-II: On-board diagnostics port. Scanners and dongles read live MPG, fuel trim and fault codes.

Authoritative References

Trusted sources and standards referenced by this calculator.

EPA — FuelEconomy.gov DOE — Fuel-Efficient Driving Tips NHTSA — Driving Safety & Efficiency SAE International — Fuel Economy Standards Consumer Reports — MPG Truth IRS — Standard Mileage Rates

Applicable Standards

EPA Fuel Economy Testing (40 CFR Part 600)CAFE — Corporate Average Fuel Economy Standards (NHTSA)WLTP — Worldwide Harmonised Light Vehicle Test ProcedureSAE J1321 / J1711 — Fuel consumption test proceduresISO 2575 — Road vehicles symbols & efficiency markings

Was This Calculator Helpful?

Report Issue

Page Information

Last Updated:

2026-09-27

Version:

2.0.0

References:

License:

Free to use for educational and professional purposes.