Deep uncertainty in future Antarctic ice-sheet mass loss makes it challenging to produce robust projections of sea-level rise. Previous studies used peak last interglacial period (LIG; ~129-116 ka) sea-level estimates to calibrate future projections of Antarctic mass loss. But LIG estimates have various depictions and interpretations across the literature. To what extent is the LIG able to inform future Antarctic contributions to sea-level rise? This study develops a Gaussian process emulator of an ice-sheet model to produce continuous probabilistic projections of Antarctic sea-level contributions over the LIG and a future high-emissions scenario. A Bayesian approach is used to condition emulator projections on a set of LIG constraints to find associated likelihoods of model parameterizations. Results show how LIG estimates inform (1) the mechanisms of past and future ice-sheet instabilities and (2) projections of future sea level rise through 2150. Best available LIG estimates do not meaningfully constrain future near-term Antarctic mass losses or physical processes. However, LIG estimates become more informative over time, as projections subject to ice-sheet instabilities become more positively skewed. Considerable uncertainties in future projections remain even if peak LIG Antarctic ice-sheet retreat is precisely known, indicating peak LIG changes are an imperfect analog for future ice-sheet sensitivities to climate warming. The efficacy of LIG constraints on Antarctic sea-level contributions also depends on assumptions about the Greenland ice sheet and LIG sea-level chronology. However, improved field measurements and understanding of LIG sea-levels still have potential to improve future sea-level projections, highlighting the importance of continued observational efforts.