"Day one" = one-off costs + one month's running costs, so you're not caught short before your first sale lands.
Runway assumes recurring costs only, starting after your day-one spend. It's a floor, not a forecast — real income from sales extends it.
A startup cost calculator is only useful if it captures the costs people actually forget — not just the obvious ones like stock or a domain name. This tool breaks spending into one-off setup costs and ongoing monthly costs separately, then works out the figure that matters most: what you genuinely need available on day one, which is your one-off spend plus a full month of running costs, so you're not caught short before your first sale even lands.
It also includes a simple runway and break-even calculation, showing how many months your available funds last with zero sales, and how many sales per month you'd need just to cover your running costs.
A full month of running costs on top of one-off setup spend. Many people budget for registration, stock, and a website, then get caught out by software subscriptions, insurance, or bank fees landing before any income arrives.
Enter costs as you'd actually pay them — including VAT if you're not VAT-registered and can't reclaim it, excluding it if you are registered and can.
Most advisers suggest at least one to two additional months of running costs on top of the "day one" figure this tool gives you, since new businesses rarely hit expected sales in the first few months.