Russia is the largest natural gas supplier to the EU. The invasion of Ukraine was followed by a cut-off of gas supplies from Russia to many EU countries, and the EU is planning to ban or dramatically reduce its dependence from Russia. To quantify the magnitude of the Russian gas used for different countries and sectors and the potential solutions to the Russian gas gap, we provide two daily resolution datasets: 1) EU27&UK daily gas supply-consumption (EUGasSC), and 2) EU27&UK daily gas reduction potential (EUGasRP). EUGasSC (from 2016-2022) provides the country- and sector-specific natural gas supply-storage-consumption (including Russian Supply Share) in the EU27&UK at a daily resolution, which is aimed to quantify the shortfalls if Russian imports were to stop. EUGasRP (for 2021) shows the maximal daily gas conservation potentials estimated by reducing demand for heating and/or increasing power generation from other sources, i.e., coal, nuclear, and biomass. They can be used as either input or reference datasets for further research in various fields, such as gas/energy modeling, carbon emission, climate change, geopolitical policy discussions, and the international gas/energy market. The units of the two datasets are KWh. Preprint of our paper: https://essd.copernicus.org/preprints/essd-2022-246/ Website of our datasets: https://eugas.herokuapp.com/ Github of our work: https://github.com/chuanlongZhou/russia_gas_essd.git The EUGasSC dataset was developed with a gas network flow simulation based on flow mass balance by combining data from multiple datasets including ENTSO-G, ENTSO-E, and Eurostat energy balance (annual and monthly). The EUGasSC dataset was validated with BP Statistical Review of World Energy and multiple Eurostat datasets. The EUGasSC shows the share of gas supplied by Russia in each country to analyze the ‘gap’ that would result from a stop of all Russian exports to Europe. The EUGasRP is developed for the potential solutions to fill the Russian gap in the EU27&UK. We analyze gas reductions for reducing demand for heating and increasing power generation from other sources, i.e., coal, nuclear, and biomass, that can substitute the gas. For the heating sector, we analyze reduction scenarios for weekdays and weekends of household and public buildings. The reduction estimations are based on empirical temperature-gas-consumption (TGC) curves based on population-weighted air temperatures using the Eurostat population dataset and ERA5 daily 2-meters air temperature data. The values provided in EUGasRP assume the following reduction scenarios: 1) households on weekdays adopt a 2 °C lower critical temperature and follow the lower 20th percentile of TGC curves to define the slope, 2) households on weekends adopt a 2 °C lower critical temperature and the lower 40th percentile of TGC curves, and 3) public buildings adopt a 4 °C lower critical temperature and the lower 20th percentile of the TGS curve. For the power sector, we assume that the electricity generated with gas can be substituted by boosting the hourly electricity generated with coal, nuclear, and biomass to certain observed higher levels. We estimate the observed higher levels by95% (as maximal gas reduction) of the maximum observed diurnal hourly capacities for coal, nuclear, and biomass for each country based on observed ENTSO-E electricity production data from 2019 to 2021. We also provide further discussions in our paper for 1) uncertainties of the two datasets, 2) the moderate scenarios for gas reductions, 3) transferring gas savings from countries with surplus to those with deficits, and 4) increasing imports from other countries like Norway, the US, and Australia from either pipelines or LNG. Based on our analysis, we argue that with plausible demand reductions, shifts in power generation towards nuclear and coal, and intra-EU and international coordination, particularly with the UK, the US, Australia, and Norway, it should be possible for the EU to make up for the sudden loss of Russian gas.