Relativistic Mass Calculator
Calculate how mass increases for objects moving at relativistic speeds
Note: Modern physics typically uses "invariant mass" (rest mass) rather than "relativistic mass." The concept of relativistic mass m = γm₀ is pedagogically useful but can be misleading. The energy-momentum relation E² = (pc)² + (m₀c²)² is preferred.
Mass Results
Rest Mass m₀
9.1090e-31 kg
0.000549 u
Relativistic Mass m = γm₀
1.2228e-30 kg
0.000736 u
Mass Increase
3.1185e-31 kg
Mass Ratio m/m₀
1.342358×
Percent Increase
34.2358%
Lorentz Factor γ
1.342358
Energy Equivalence
Rest Energy m₀c²
0.5111 MeV
Total Energy mc²
0.6860 MeV
Kinetic Energy
2.8029e-14 J
Mass at Various Speeds
| Velocity (%c) | γ Factor | Relativistic Mass |
|---|---|---|
| 10.00% | 1.005038 | 9.1549e-31 kg |
| 50.00% | 1.154701 | 1.0518e-30 kg |
| 90.00% | 2.294157 | 2.0897e-30 kg |
| 99.00% | 7.088812 | 6.4572e-30 kg |
| 99.90% | 22.366272 | 2.0373e-29 kg |
| 99.99% | 70.712446 | 6.4412e-29 kg |
About Relativistic Mass
The concept of relativistic mass m = γm₀ shows how a particle's inertia increases as it approaches the speed of light. At v = 0.99c, mass is ~7× rest mass; at v = 0.9999c, it's ~70× rest mass. This explains why infinite energy would be needed to accelerate a massive particle to the speed of light.