Sea Level Rise Calculator
Sea level rise is one of the most consequential impacts of climate change for coastal communities, infrastructure, and ecosystems. Global mean sea level has risen approximately 100 mm (about 4 inches) since 1993 based on satellite altimetry measurements from NOAA and NASA. The current global rate is approximately 3.7 mm per year and accelerating. Local rates vary significantly: Louisiana and Virginia experience rates of 6 to 9 mm per year due to land subsidence, while parts of Alaska see sea level falling due to post-glacial land uplift. This calculator projects total sea level rise over a chosen number of years using a constant annual rate. For planning, always use NOAA scenario-based projections.
Sea level rise projection formula
Total rise (mm) = Annual rate (mm/yr) * Years
Total rise (cm) = Total rise (mm) / 10
Total rise (inches) = Total rise (mm) / 25.4
Total rise (feet) = Total rise (inches) / 12
This linear projection assumes a constant rate throughout the projection period. Because sea level rise is accelerating due to increased ice sheet melt and thermal expansion, linear projections underestimate future rise for time horizons beyond 20 to 30 years. Use NOAA's scenario-based projections for infrastructure planning.
Key sea level rise facts
- Global mean sea level has risen about 100 mm (4 inches) since satellite measurements began in 1993 (NASA/NOAA).
- NOAA's 2022 report projects 0.3 to 2.5 m of global mean sea level rise by 2100 depending on emissions scenario.
- A 1-foot rise in sea level extends storm surge flooding 50 to 100 feet inland on low-gradient coastlines.
- More than 40 percent of the US population lives in coastal counties (NOAA).
- Tide gauge data from NOAA's Center for Operational Oceanographic Products and Services goes back over 100 years for some US stations.
Frequently asked questions
How fast is sea level rising globally?
The global mean sea level rise rate is approximately 3.7 mm per year as of 2023, according to NOAA satellite altimetry data. The rate has been accelerating: it was about 2.1 mm per year from 1993 to 2002 and about 4.8 mm per year from 2013 to 2022.
Why does sea level rise vary by location?
Local sea level change depends on global warming (ocean volume), regional ocean circulation changes, gravitational effects from melting ice sheets, and vertical land motion (land subsidence or uplift). Some US East Coast locations see rates 3 to 4 times the global average due to land subsidence.
What are the NOAA sea level rise scenarios?
NOAA's 2022 Sea Level Rise Technical Report provides six scenarios for US waters through 2150: Low (0.3 m), Intermediate-Low (0.5 m), Intermediate (1.0 m), Intermediate-High (1.5 m), High (2.0 m), and Extreme (2.5 m) by 2100 relative to 2000.
Is this a linear projection?
Yes, this calculator uses a simple linear projection (constant annual rate). Real sea level rise is accelerating, so linear projections underestimate future rise for longer time horizons. For planning purposes, use NOAA scenario-based projections rather than linear extrapolation.
Where can I find the local sea level rise rate for my location?
NOAA's Tides and Currents website (tidesandcurrents.noaa.gov) provides local sea level trends from long-term tide gauge records for hundreds of US stations. NOAA's Sea Level Rise Viewer also provides interactive maps for local planning.
Official sources
- NOAA: Sea Level Trends (Tide Gauges).
- NOAA: Sea Level Rise Technical Report 2022.
- NASA: NASA Sea Level Change Portal.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.