The romantic version of SaaS side projects: build in evenings and weekends for a year, hit $10K MRR, quit your job, scale to a million. The realistic version: spend 18 months building something that reaches $1-2K MRR, plateau, and face the decision of whether this is worth going full-time for.
Most side project SaaS stalls not because the product is bad or the market is wrong, but because a side project gets side project energy — fragmented attention, delayed decisions, slow iteration, and customer conversations that happen monthly instead of weekly.
The honest framework for side project SaaS:
Define your commit criteria before you start. What MRR number would make you comfortable going full-time? What growth rate at that MRR would give you confidence? Set these criteria before you're emotionally invested in a specific number, not after.
Track the growth rate, not just the level. A side project at $2K MRR growing 15% month-over-month is more interesting than one at $3K MRR that's been flat for 4 months. The growth rate tells you whether the business has momentum that would compound with full-time attention.
The "what would happen with full-time focus" thought experiment. For your specific business, what would change if you had 40 hours per week instead of 8? Would you be able to talk to customers 5x more? Would you be able to iterate 5x faster? If the answer is no — if the constraint isn't time but something more fundamental — then going full-time won't fix it.
The walk-away signal: 6 months of full earnest effort with no growth. Not because the idea is bad, but because the combination of this idea, this market, and this founder is not producing momentum. The willingness to walk away from a non-working idea is what frees you for the working one.
Build honestly. Decide clearly. Commit fully when the signal is there.