Use the official GOV.UK State Pension forecast service and compare it with your National Insurance record. Check your qualifying years, any gaps, missing National Insurance credits, and whether periods of contracted-out employment affect the estimate. If you are considering voluntary contributions, check first whether they are likely to improve your forecast and ask the Future Pension Centre if you need guidance before paying. Remember that the forecast is an estimate based on your circumstances and future contributions, so your eventual State Pension is decided by the Department for Work and Pensions.